Return to Continuing Maintenance

"Status of the 1401 Data Center - 2022"

Hosted by Carl Claunch from November 2018 to July 2021 (off to Florida ;--))
Now continued by mostly Stan Paddock and Jack Ghiselli

The CHM e-mail announcement list system we use,
e-mail list addresses starting with "Volunteer-1401- "
failed starting Monday August 29, 2022.

Until this is fixed, will announce
updates using e-mail addresses from Team Bios
- Restoration Team, - Docents, - Remote
plus Poppy Haraldson and Jessse Nichols of CHM.
    Suggestions accepted.


Some relaxed pictures taken Wednesday, March 30, 2022
2022 Maintenance
For 2018 through 2021, click here.
2022 Demonstrations
For 2018 -2019, click here.
Jan - 5, 12, 19, 26
Feb - 2, 9, 16
Mar - 16, 20, 22, 23, 26, 30
      Group Pictures
Apr - 9, 13, 20, 27 Apr - 30
May - 4, 11, 17&18, 24&25, 31 May - 7, 14, 18, 21, 28
Jun - 1, 7, 14&15, 21&22, 29-A.C. Jun - 4, 11, 22, 25, 29
Jul - 6, 13, 20, 27 Jul - 2, 6, 9, 13, 16, 30
Aug - 3, 10, ?, 17, 24, 31 Aug - 3, 6, 7, 13, 17, 19, 20 !!, 24, 27
Sept - 7 14 16 Sept - 3, 7, 8, 10, 14, 21,

Wednesday, September 21, 2022 from Bill Worthington
Pat Buder and I led the 1401 demonstration last Wednesday for about 15 visitors. There were about another 8 who joined us later. With its being a smaller group, we found there were more questions from the visitors.

CT performed admirably. Big thanks to the restoration team.


Friday, September 16, 2022 - from Stan Paddock
? occasional missing phase from DE circuit breaker ? !!
Stan Paddock 5.0
Bill Newman 5.0

Background from recent status reports.

  1. Problem switching the circuit breakers for the German system.
  2. CHM called in an electrical contractor to replace the three wire circuit breaker.
  3. The following is a report from Frank King on the next work day.;
    "Hi, Stan,

    The German 1401 power converter acted up for the first time I have ever seen.
    When I tried to power on the German 1401, the power converter went down immediately; it has an internal circuit breaker that will reset on its own.
    After opening the 1402, looking at the 30 amp circuit breakers, I tried it again (It had reset by this time).
    Then, Mason and I took the tape circuits off line; that didn’t help.
    Mason then suggested we trip the 1402 circuit breakers one at a time.
    When we tripped the inner most 30 amp breaker the converter didn’t go down when powering up the German 1401.

    We then reset the breaker and tried it one more time.
    It stayed up.
    So we restored tape power and tried it again.
    It stayed UP.

    Frank King"
  4. The next work day, everything seemed to be OK.
  5. Bill Newman and Stan Paddock decided to come in on a Friday work day.
    All of the problems shown in number 3 above showed up again.
    Bill brought out a electrical meter and checked the power line from the circuit breakers on the power panel and the power convert.
    When the system was acting up, there was a missing leg from the circuit breakers.
  6. The problem was traced down to the three wire circuit breakers installed in number 2 above.
  7. We would request the CHM to have the electric contractor come back and fix the problem.
Stan Paddock

Wednesday, September 14, 2022 - from Pat Buder

At 3:00pm Tim Robinson, Bill Worthington, and I gave the demo to 42 visitors. We ran on CT. It and the rest of the equipment that we used performed well.


In the evening we did a special demo for a group of 50 Arizona State University Electrical Engineering alumni. ASU is Robert Garner's alma mater (go Sun Devils). Last week Jack Ghiselli used his revised and improved banner program to print two welcome banners for the group.

We ran on CT, which performed perfectly. Robert was in the machine area to help. I gave a slightly shorter than usual demo (about 25 minutes) due to the late hour. It was well received.

As usual, thanks to the restoration team for providing working CompuSaurs.

September 14, 2022 - from Stan Paddock
Mason King 6.0
Frank King 6.0
Stan Paddock 6.0
Tom Szolyga 6.0
Marc Verdiell 6.0
Dale Jelsema 4.0
Ed Thelen 3.0
Robert Garner 6.0

Frank King, Mason King Dale Jelsema and Mason King continued work on the German 1402 card punch. Several circuits were checked and unfortunately the circuits checked worked as designed.
Frank and Dale

Mason King learning
how the 1402 punch works.
Dag Spicer, the Museum’s senior curator paid us a visit.
A large number of visitors wandered into the 1401 room.
Dag played docent and to the random visitors told them about the IBM 1401 and answered questions about the CHM Museum..
Marc got the keyboard for the public keyboard reassembled.
Unfortunately the keypunch rejected the implant of the keyboard.
We are looking for success next week.


September 10, (Saturday) 2022 - from Jack Ghiselli
Paul Laughton and I gave the 1401 demo on Saturday, 9/10 to 28 people, and mini-demos to 8 more who wandered in before or after. We had international visitors from Argentina and Switzerland. We had one visitor who had worked on Unit-Record Equipment and 1401 and 7090 computers in the Navy at Mare Island beginning in 1959 and was happy to see our demonstration lab.

We ran on CT, which performed well. We got a few read check errors on the CT 1402 Reader immediately after power-up, but these disappeared after some minutes of warm-up. Tape Drive #1 is still marked Out of Service, so we used Tape Drives #2, #3, and #4. We didn't see any problems with #3 as Pat had seen last Wednesday.

All three 026 Keypunches worked OK. The Amazing Restoration Team apparently fixed the poor printing on Keypunch #3 (closest to the door) and the failure to feed on Keypunch #2. Having all three Keypunches made the BigPrint punching go quite quickly.

Apparently, when I did the demo last Thursday, I somehow knocked the A/V battery charger cord from the wall, so the rechargeable batteries didn't get charged. We loaded disposable alkaline batteries into the radio microphones for the demo. Paul found that one of the power outlets in the A/V closet didn't power the charger, so he switched to the other. The charger should show red lights when it is charging. Rechargeable batteries should be ready for the next demo.

--Jack Ghiselli, Cell 408-839-1051

September 8, (Thursday) 2022 - from Jack Ghiselli
Mike Albaugh and I gave a special 1401 demo today to 14 students and staff from St Helena High School in northern California. After the main demo, 22 additional visitors came by and we gave mini-demos. We had several visitors from the Economics conference upstairs, and foreign visitors from Brazil, China, Estonia, and Ukraine.

We used CT which generally ran well.

026 Keypunch #2 is still INOP (doesn't feed). #3 (nearest the door) was printing too light to read. We tried reversing its ribbon and that seemed to help a little, but it probably needs a new ribbon. So only 026 Keypunch #1 (farthest from the door) was usable for the demo. #1 generally worked well, but it still has the problem where cards sometimes jam up when transferring from the Read station to the output stacker. Usually we can pull them out by hand, though.

The 083 Sorter worked OK for the demo. It still seems to handle input cards roughly, crumples some, and sometimes the last few cards of an input deck don't feed. It's also making some unusual mechanical noises.

The 001 Manual Keypunch, which was INOP a few days ago due to card fragments jammed into it. Somebody apparently found a card saw and cleared out the fragments. The card saw is on the CT 1402. We saw some clues that it might have been Stan Paddock. Whoever it was, thank you.

We found CT 729 Tape Drive #3 loaded with a bunch of loose tape dumped in the vacuum columns. So, for the demo we used only Drives #2 and #4, which ran fine. After the demo, we manually rewound the loose tape back on the the reels of #3, and were able to get it to rewind/unload. Not sure if it has problems or not. Drive #1 is still marked OUT OF OPERATION, so we didn't try to use it.

After the demos, we punched some object decks on the CT 1402 Punch, which worked beautifully. Thank you, Restoration Team.

--Jack Ghiselli, Cell 408-839-1051

September 7, 2022 - Demo - from Pat Buder
On Wednesday I gave the demo to an engaged group of 24 people. No assistant showed up. No other guests appeared before or after the main demo.

I ran on CT, which worked well. I did not prep DE because Frank & Mason were still working on the 1402 punch. It was not needed.

The only CT problem was that drive #3 (2nd from right) dumped tape into the right column when doing a rewind. Drives #2 & #4 worked fine.

026 keypunches #1 and #3 ran fine, as did the 001. I didn't try 026 #2, which looked like it was being worked on. With the small group two keypunches were sufficient.

September 7, 2022 - from Stan Paddock and Robert Garner
Frank King 6.0
Mason King 6.0
Stan Paddock 6.0
Robert Garner 2.0

Frank King and his grandson Mason spent the day working on the German 1402 card punch.
A lack of +20 volts has been traced as PUNCH CHECK being on.
While two errors lights have shown, progress has been advanced.

Stan Paddock worked on the PC to IBM 029 in the Leibert.
Progress in the code is getting close.


Aug. 24, 2022

Sept. 7, 2022
Robert Garner took before and after pictures of the DE system main breakers.
"… it appears that they replaced all 3 with identical units. (It’s hard to discern the subtle differences.)"

September 3, 2022 - from Jack Ghiselli
Steve Madsen and I gave the 1401 Demo today to 24 people, plus mini-demos for 10 who wandered in later. Our only foreign visitors were from Mexico City. Lots of questions from this group.

We used CT which generally worked well. We did have a problem with what seems to be a bad spot on the CT 1403 printer ribbon. We had tested BigPrint and Powers of Two before the demo and printing looked good. However during the actual demo, our first BigPrint printed so light it was mostly unreadable (see photo below). We re-ran it three times and no improvement. Kind of embarrassing, but we skipped that and continued with the demo. To recover, we left the CT1403 print chain engaged, so that the ribbon would keep moving while we talked about other things. Eventually, I guess the ribbon got to a good spot, and we were able to print successfully later. Or perhaps we don't have Paul Laughton's clever touch at slamming the carriage closed firmly, and it's not really a ribbon problem. Unsure. Suggest following demo'ers check for this.

The 001 Manual Keypunch is INOP. It has a fragment of a card jammed into the mechanism and we were unable to clear it. Sorry for my ignorance, but does the 001 need tools to clear a jam? We left a sign on it and hopefully visitors won't damage it further.

For the microphones, we used Paul Laughton's rechargeable batteries. When we put the old batteries into the wall charger, we don't see any blinking lights. Is the charger still working? Next demo please check whether we got the batteries re-charged correctly.

Some continuing minor problems continue, none of which affect the demo:

  • Keypunch #2 is INOP. Doesn't feed or register cards. We left a sign on it. Important only if we have a very large group.

  • CT Tape Drive #1 is marked INOP so we didn't use it.

  • The 083 Sorter moves cards sufficiently to demo. However, it doesn't REALLY sort correctly, so you cannot put a deck in sequence. As a result the sample Ken-Ross-style sort data decks I produced last Wednesday have lost my carefully marked First and Last cards and top markings (artist's "sigh" here). Unfortunately, the only card stock I'd found last Wednesday was completely unprinted, so it's difficult to find the correct orientation for 12-Edge, 9-Edge, and Front/back. Again, this is NOT a big problem for the demo.
Sarah from the front desk came in with a query she'd received apparently from an ex-IBM'er who wanted to know where he could buy IBM punch card stock. We referred her to Bob Garner or Dag Spicer. Ha! We ducked that one!

--Jack Ghiselli, Cell 408-839-1051

August 31, 2022 - from Robert Garner
Stan Paddock was not in, he asked Robert Garner for a status report. Stan's report (below) received Sept. 8

I was in for 2 hours.

Frank and Mason worked on the DE 1402 punch.
(Mason told me that the Pacific Power breaker tripped when he first turned on the DE 1401.
Tried it again w/breakers in 1402 off, then back on, then DE powered up the 2nd time.)

Yes, Dale Jelsema was in today! < dale . jelsema @ gmail . com >
Photo here: (I’ll ask him for his bio.)
He asked if he could borrow some of the 1401 manuals to get up to speed. (like the 1401 CE manual). I replied no problem.

I didn’t see Marc. Tom [Szolyga] was in.


— Robert

Stan's report (below) received Sept. 8
Report from Frank King;

Hi, Stan, the German 1401 power converter acted up for the first time I have ever seen.
When I tried to power on the German 1401, the power converter went down immediately, it has an internal circuit breaker that will reset on its own.
After opening the 1402, looking at the 30 amp circuit breakers, I tried it again (It had reset by this time).
Then, Mason and I took the tape circuits off line; that didn’t help.
Mason then suggested we trip the 1402 circuit breakers one at a time.
When we tripped the inner most 30 amp breaker the converter didn’t go down when powering up the German 1401. We then reset the breaker and tried it one more time. It stayed up.
So we restored tape power and tried it again.
It stayed UP.

Because we had a 1402 down and no schematic for the power converter we decided to work on the 1402.
We found a circuit breaker (number 2) of the set that latches and only runs when the clutch is tripped.
It was failing to open, so we took it out lubed it and put it back. It was in the sequence of keeping up.
With card movement, our test showed no change. ;-(

Mason and I left around 15:00 Dale left a little before us Tom was still there.

From Tom Szolyga;

Hi Stan,

Missed you today! I worked on the following items:
  • Created a real schematic for the Blue Box line driver and line terminator circuits.
  • Ran a simulation of these two circuits connected to each other.
  • Collected the parts for the next version of the German Project breadboard and assembled them. (See attached) I has the ATmega 2560 on the bottom, the board with terminal strip screws for each signal is in the middle and the diagnostic display is on top. There is a plug board for test circuits too. Everything is mounted on a plastic plate so the breadboard circuit will not fall apart.
I will be out of town next week, so I will see you in 2 weeks.

Best regards,


August 27, 2022 - from Jack Ghiselli, Stan Paddock, Paul Laughton, Robert Garner
Saturday demo, blocked breaker, demo batteries, circuit breaker cycling ON/OFF
From. Luis Valencia, Facilities Manager, CHM - Mon 8/29/2022 2:00 PM
Hello All
Breaker was replaced last Friday after hours, Electrician assessed the issue before replacing the breaker, no overloading or shortcuts were found.

Thank you,

Luis Valencia

It appears that the Saturday Demos were run using correct power components.

from Jack Ghiselli, - Saturday demo

Hi 1401 demo and restoration teams,
Hooray, Stan, for the temporary fix. When Steve Madsen, Paul Laughton, and I came in to demo Saturday 8/27, the "1401 GERMAN" ganged circuit breakers were ON. Stan's email mentioned he had taped them on. We didn't see any tape externally so we assume it was internal. Anyway, we WERE able to power-on the Pacific Power 60-to-50 Hertz converter, so that's good. As it happened, everything on the CT 1401 was working well for the demo, so we did NOT need the DE 1401, and didn't try to power it on. But it was reassuring that we COULD have used DE if we'd needed it. Per Stan's email, when we powered everything down, we left the "!401 GERMAN" breakers ON. My understanding is that with the Pacific Power unit OFF, all the outlets and boxes are safely un-powered. Please advise if and when the breakers get replaced.

--Jack Ghiselli, Cell 408-839-1051

from Stan Paddock, - blocked breaker

Somebody indicated that if the German system was needed for a demonstration, the circuit breakers would not switch on.

To make sure the German system was ready for the Saturday demonstration, I turned the three German circuit breakers on and taped the three circuits in the on position.

I put a sign on the door to the Libert room with instructions to use the main power switch for the power converter as the only off/on switch for the German system.

The current connection is still 100% safe.

This current will go back to the original configure when the electrician comes in and replaces the three circuit breakers.


from Paul Laughton, - demo batteries

There are now new sets of rechargeable AA batteries and a new charger. There are two sets of four. One set has black band at the top. The other has no band. All four of the batteries in a set should be swapped before the demo. The ones in the charger going into the mics. The ones in mics going into the charger.

Some non rechargeable batteries will remain in the drawer to use in case of problem.


from Robert Garner, - circuit breaker cycling ON/OFF

Ed Thelen noted that the Circuit Breaker Box was likely from Seimens, based on the "catalog number" in the picture.

I also wonder if there’s a grade for higher duty on/off cycling?

We cycle the circuit breakers ON and OFF at least 100 times a year. This failed breaker was cycled at least 1500 times - not its usual expected service?

1401 Demo, Wednesday, 8/24/22 from Paul Laughton
The volunteer signup page did not show ((full) not indicated) that anyone had signed up as the Assistant. I recruited Kathleen O'Brien, a retired computer science professor and my wife, to be my beautiful assistant. When we arrived on site, Bill Worthington was there. He said that he had signed up weeks ago. I decided to split the Assistant role. That worked out well.

The DE circuit breaker refused to be "unbroken" as previously reported. Emails from Robert Garner and others indicate that the problem is being investigated.
(See report below this report)

The CT 1403 printer was left in an inoperable state. The Ink ribbon was stuck at the end of the reel. The paper was jamming as it moved. Robert Garner, Frank King and Bill teamed up and got it fixed before the demo.

We had about 50 guests with visitors from the UK, Germany, Columbia, Egypt, Georgia (the nation) as well as from the USA.

Just before the demo started, I noted that the Mic #2 battery was at 2/3rds. I replaced the batteries.

The 1/2 hour demo went well with virtually all guests remaining in the room through to the end of the demo. We spent about 15 minutes doing Big Prints after the demo.

A big thanks to Bill, Kathleen, Robert and Frank for their able assistance.


August 24, 2022 - from Robert Garner and Stan Paddock
German circuit breakers solidly not engaging, and Status Report
from Robert Garner
The (90-Amp) circuit breakers for the DE (German) 1401 adamantly (after >10 attempts) do not engage/remain on, per the following video:
Editor's Note: I included this frame copy from the movie, instead of a link to the 20 MByte movie. The movie shows the (90 amp 1401 German) circuit breaker being changed from OFF position to ON position and immediately going to the TRIPPED position as shown.

It appears that we’re now unable to turn on the DE 1401.

Hoping an electrician can replace ‘em.
(I wonder if there's a circuit breaker model spec’d for more frequent cycling, say several 100 on-offs per year?)


- Robert

PS. The Pacific Power unit was turned off during the attempts to engage the circuit breakers.

Jennifer Alexander e-mailed "Facilities Manager Luis will follow up on this."

from Stan Paddock

People who attended the CHM were:
Frank King 6.0
Stan Paddock 6.0
Tom Szolyga 6.0
Marc Verdiell 6.0
Robert Garner 2.0
Mason King 6.0

Frank and Mason continued there work on the German 1402 card punch.
They traced the problem to permissive relay 26.
Frank and Mason pulled all of the permissive relays related to the punch and brought them to the workshop.

We have a permissive relay tester that we have not used for years.
When we tried to use it, we found that the power supply for the HP laptop was defunct.

I contacted Dennis Cassar of the CHM IT department to see if he could supply a replacement power supply.
In less than 10 minutes, he brought a replacement power supply to our workshop.
Thanks Dennis.
I showed Mason how to run the permissive relay tester.
Mason took off running the tester as if he had been using it forever.
Relay 26 was totally bonkers and was replaced.
Another relay was also totally bonkers and was replaced.
All relays were replaced into the German IBM 1402 and tested again.
Damn thing punched card!
Now if did the punch without a PUNCH CHECK and a PUNCH STOP error, we would done.
Way to go Frank and Mason.


August 20, 2022 - from Jack Ghiselli
IMMEDIATE PROBLEM FOR CHM FACILITIES: - with many added comments

It appears that at least one of ganged circuit breakers 35-37-39 (labelled "1401 GERMAN") is faulty. Recommend replacing them all. Until this is fixed, it is impossible to power-up the DE 1401.

On Saturday, 8/20/2022, Steve Madsen and I gave the 1401 Demo to 48 visitors, and then a mini-demo for 2 visitors afterwards. We had visitors from all over the USA, and foreign visitors from the Czech Republic (near Brno), France (Toulouse), Japan (near Tokyo), and the UK (north of London). This particular group had lots of technical questions after the demo was over, so we spent quite a bit of time simultaneously answering and running BigPrints. We demonstrated the 083 Sorter, and ran the demo on CT, using 729 Tape Drives 2-4, since #1 had been switched NOT OPERATIONAL. During pre-demo setup, we worked around several hardware problems (described below), and the demo itself went well.

First, DE Power:
Pat Buder's report from Wed 8/17 suggested that the CT 1402 was refusing to read cards, and recommended using DE for the demo. When we powered on the breakers for "1401 GERMAN", they appeared to turn fully on, but we were unable to power-on the Pacific Power 60-to-50 Hertz power converter. A few green LEDs came on, but we couldn't turn on the three voltage displays at the top. This is exactly the symptom Paul Laughton reported in our email exchange of 8/13. I continue to believe that the problem is in the wall circuit breakers, not the Pacific Power unit. I turned the "1401 GERMAN" breakers off and then firmly back on. This apparently worked, because we were then able to turn the Pacific Power unit on normally.

Unfortunately, when we tried loading decks on the DE 1402, it refused to read cards. We tried using NON PROCESS RUNOUT to exercise the 1402 mechanism, as suggested by the Restoration Team. But, no luck. So, we decided to try CT, although both Pat Buder (Wed 8/17) and Paul Laughton (Thurs 8/18) had reported that the CT 1402 was refusing to load decks. For us, the CT 1402 worked perfectly. I suspect this is due to the Amazing Steve Madsen, who gave it a "stern talking-to".

The Amazing S. M. also demonstrated his extensive IBM training by clearing the card jam left in the 083 Sorter as an exercise for us. It was an ugly multi-card jam, and you should see the Amazing S. M. go to work with needle-nosed pliers. He got that 083 puppy working perfectly in time for the demo. Yay, Steve!

One minor issue:
After the demo, while we were rewinding CT tapes, 729 Drive #2 dumped tape into the bottom of the input vacuum column. We were able to Unload and manually wind the tape back on the take-up reel, and then it was OK. Possibly an intermittent vacuum-column problem?
Happened only once.

After the demo was over and visitors had left, we decided to try loading decks on DE. Guess what?
The DE 1402 loaded decks just fine.
Perhaps this means DE needs some warm-up time? It had been powered up for 40 minutes while we ran the demo on CT.

More about DE Power:
Now, we powered down the DE1401, the Pacific Power unit, and the "1401 GERMAN" circuit breakers. Just for grins, we decided to try power-on one last time, and I'm glad we did. This time, we found that the ganged 34-37-39 ("1402 GERMAN") circuit breakers would not turn on. When you flip the breakers on, they immediately bounce back about half-way, and give no power to the Pacific Power unit. Just to be clear, now they are WORSE than before. As noted above, I'd recommend that CHM Facilities replace all three breakers. Until then, DE is unusable. It would be nice to fix this before the Restoration Team and Demo Team come in Wednesday 8/24.

--Jack Ghiselli, Cell 408-839-1051

From Robert Garner, 8/20/2022 5:04 PM
The three ganged circuit breakers that supply the Pacific Power 60-to-50-Hz power converter for the DE 1401 are tripping.
Either the circuit breakers are degraded, or it’s possible that the Pacific power 390-G unit is tripping them.*
While we can perform a few diagnostic test on the Pacific Power unit,** it might also be helpful if we could get an electrician in to swap out the circuit breakers, just to eliminate them as a possible source of the problem.


— Robert

* The 390-G comprises three independent power converter units, one for each phase:
One of them could be tripping its circuit breaker, but because they’re ganged, all of them go belly up.

** With the DE 1401 turned off (no load), we could disable each of the three converters one-by-one to see if one of them is tripping the breakers. But it may only be happening under full load, which would involve further diagnostic testing: looking at the phase current waveforms as power comes up.

from Stan Paddock, 8/21/2022 12:02 PM
If the power converter is ON when the GERMAN circuits are turned on, frequently the circuit breakers,

If the Power converter is always turned off before turning the GERMAN circuit breakers off, this problem will never happen.


from Robert Garner, 8/21/2022 3:24 PM
Stan, et al,

> If the Power converter is always turned off before turning the GERMAN circuit breakers off, this problem will never happen.

Jack’s message implied that the Pacific Power converter was indeed off before he turned on the circuit breakers (i.e., the conventional DE 1401 bring-up order):
“When we powered on the breakers for "1401 GERMAN", they appeared to turn fully on, but we were unable to power-on the Pacific Power 60-to-50 Hertz power converter. A few green LEDs came on, but we couldn't turn on the three voltage displays at the top. This is exactly the symptom Paul Laughton reported in our email exchange of 8/13.”

Re: Frank’s note…
"The circuit breakers for the DE machines converter have tripped when turning them on for a couple of years at least. A push back reset and then on, has always worked for me. I have never had it fail. It generally trips off about 1/2 the time or less.
This is something to consider. The main circuit breaker for the converter is always off when this has happened. i.e. there is no load on the tripping circuit breakers?”
… reaffirms that we’ve had this issue for some time. As Jack noted, it could indeed be an issue with the circuit breakers, since the power converter is typically off before the breakers are turned on.

Or perhaps our Pacific Power unit (or the 3-phase AC wiring) has an AC leak/low-impedance path to ground or between the phases (that’s tripping the breakers as they’re first turned on)? Recall that Ron Crane modified the Pacific Power unit to help reduce the reactive power (added caps I presume). Perhaps that mod is upsetting the breakers? An electrician could help determine the issue.


— Robert

p.s. I may have confused the discussion by postulating a turned-on Pacific Power converter when the circuit breakers are first turned on. Sorry about that… (After all, as Frank noted, why are they be tripping with no load?)

August 19, 2022, - from Paul Laughton and Marc Verdiell
Flaky CT - not LOADing programs
from Paul Laughton
was giving a demo to a private party Thursday around 4:00 PM.
CT would not LOAD any programs. Pressing LOAD caused the CPU CHECK RESET light to turn on without reading any cards.


from Marc Verdiell
I experienced the same as Paul. Was refusing to read any cards. Then after a while it started to work all of a sudden. CT system also, several occasions.

17 August 17, 2022, - from Stan Paddock
People who attended the CHM were:
Robert Garner 3.0
Stan Paddock 6.0
Tom Szolyga 6.0
Marc Verdiell 6.0
From Tom:

Yesterday I accomplished:

  • Soldered together new breadboard. The breadboard plugs into the Arduino board. The LCD panel plugs into the breadboard. The breadboard has screw terminals for each Arduino signal. This config allows signal connections to the Arduino while keeping the LCD display diagnostic capability.

  • I Created LTspice XVII setup and analysis of 1401 cable driver and terminator. (See attached) In the bottom pane is the circuit for the IBM cable driver connected to the IBM cable terminator. In the top pane are the waveforms for the voltages at the Input, on the Cable and the Output. I chose a transition period of 1s to easily see the switching points. According to the IBM ADL pages, the Input (on the left side) varies between 0V and -12V. The Output (on the left) varies between 0V and -12V. The simulation shows these values. The simulation predicts the voltage on the cable varies between 1V and -1V.
    Click to enlarge
Best regards,



Marc had taken the 029 keyboard home and see if he is able to fix it there.
Today he continued his work on the keyboard in the shop.
He is getting closer but the "A" key on the keyboard is still not repaired.
Taking the keyboard structure apart, fixing the problem and putting the keyboard again is not easy to do.


Stan attempted to find the problem with the punch problem on the GERMAN 1401 system.
Going through the GERMAN ALDs but did not get far.
I will continue next week.


August 17, 2022 - from Pat Buder
Problems - Sorter, CT read
On Wednesday Bill Worthington, Paul Laughton, and I gave the demo to 50 visitors from Slovakia, Switzerland, and other places. We did mini-demos for another 15 before and after the main demo.

We ran on CT, which had the problems described below. All tapes and keypunches worked fine.

Sorter problem
Initially all sorted cards dropped into the reject bin. Choosing a second column had the same results. I reached over to verify the settings of the front panel switches, selector knob, and buttons. I was not in front of the machine so I didn't notice that the SORT/TEST switch was not up. It is not uncommon for visitors to reach beyond the rail to play with these switches, which is what had happened here.
During the struggles, I managed to cause a card jam in the sorter - sorry.

CT Problem
The CT 1402 read and ran BigPrint successfully before the demo. During and after the demo, there were several times when the motor would start but no cards would be read. As Jack, Paul, Marc, and I have recently noted this is a chronic intermittent problem.

I would recommend that docents do not allow visitors to press the 1402 LOAD or START buttons during the demo because this presents an example of unacceptable visitor behavior at times when the lab is unstaffed. We should be encouraging never touching anything beyond the fence.

While CT is closer to the keypunches and more convenient for demos, I plan to use DE until the CT 1402 intermittent problem is fixed.


August ?, 2022 from Robert Garner and Marc Verdiell
Repair of our IBM 029 keyboard "A" key at Marc's home
Note: from the August 10th report
> Sometime when the 1401 room was un-attended , the "A" key on that machine was broken.
> Marc volunteered to take the keyboard home and see if he is able to fix it.

An idea of the IBM 029 keyboard complexity cam be viewed on Marc's Youtube series -
IBM 029 Keypunch Restoration 6 - Insanely Complicated Keyboard
For more on the IBM 029 keypunch click here.

Material from e-mails is below

Marc (unexpectantly) noticed that several of the “Interlock Disks” were misplaced from their proper locations (they look like small donuts).
Camera, microphone and lamp are for creating Marc's wildly popular Youtube series.

I wonder if that could have contributed to the “A” key becoming stuck (i.e., a missing interlock disk)??

(click to enlarge)

The diagram is on page 4-41 of that document.

The A-key is repaired, but I think I need to revise my story about the interlock disks, I might have caused that. Anyhow, I fixed that mess and did not lose any disk, but in doing so I created another one, now having to reseat all the springs on the code bars, for the next session I guess. I did not lose any spring either. At least not yet :--))
Never a dull moment.


August 13, 2022 - from Steven Madsen, Jack Ghiselli and Paul Laughton
from Jack Ghiselli
Just asking. In the 1401 Demo Lab, is it a good idea to have the extra 029 Keypunch outside the barrier where visitors can touch it? We already have the 1902-vintage Model 001 manual keypunch and encourage visitors to play with it. So, they'll probably assume it's OK to bang on the 029, which is easier to break. Marc and Stan reported at least one damage incident. Normally we don't need or use the 029 during demos (we use the three 026 Keypunches inside the barrier). Should it be removed? That 029 is in pretty good shape, and has been used in the past for supervised demos elsewhere in the CHM or off-site (e.g. the Maker Fair), so maybe it should be reserved for that purpose? Decisions like this are above my pay grade, so I'm just asking.

response by Marc

I'll surmise that it's a very bad idea. It's too complex and precious of a machine for the average visitor to understand, much less to operate safely. The only thing they'll manage to do is to break it.
comment by Grant Saviers
I recall the keypunch room from my student days. 30x 026's about 1/4 of which were always inoperative, even though the IBM FE came once a week to fix them and some of us staff students could undo simple problems.

A not broken program drum was usually unobtanium.

Use restricted to Docent demos sounds like a good idea to me.

Grant Saviers

from Stephen Madsen to Paul Laughton
Paul Laughton and I demonstrated the IBM 1401 to 40 people. We had visitors from Germany, Toronto, Hong Kong, and China. While running Bigprint we had a reader check and an operator error (pressed LOAD instead of START). That deck was marked because it might have some cards out of position.

We did not start the DE machine, because the Power Converter was not working. All other equipment worked fine.

After the demo, a group of 30 students from Japan came in. We let them punch name cards and ran Bigprint for them.

Stephen H. Madsen

from Jack Ghiselli
Hi Steve,
Great demo report! I'm not exactly sure what you meant by "Power Converter was not working". I have noticed that the "1401 GERMAN" circuit breaker set (ganged breakers 35-37-39) are a little flaky. Sometimes when you flip them on, they bounce back a little and DO NOT TURN FULLY ON. In this case, of course, when you try to turn on the DE Power Converter, nothing happens, since it has no input power. My solution has been to turn the "1401 GERMAN" breakers back off, then forcefully turn them on, holding firmly and verifying that they go ALL THE WAY ON. See if that solves the problem.

When I get back in, I'll run VOBJ to analyze the suspect (marked) BIGPRINT deck and fix it if necessary.

--Jack Ghiselli, Cell 408-839-1051

Comment by Paul Lauughton
I noticed the problem with the flak DE circuit breaker. The problem that I noticed was not that exactly. The converter was getting some sort of power. The three phase activation section at the top was not responding to the start button press.

Aug 10, 2022, from Stan Paddock
People who attended the CHM were:
Robert Garner 2.0
Frank King 6.0
Mason King 6.0
Marc Verdiell 6.0


Frank continued his work on the German 1402 card punch, with the help of his grandson Mason, who clearly inherited the debug-anything genes.
While they tested a number of functions of the 1402 punch, all of those functions seems to be operating correctly.
The story of the 1402 punch continues on.

The docents cited an error with keypunch #1 not feeding cards into the stacker correctly.
Frank using his 50 years experience working on IBM keypunches, fixed the problem quickly.

From Marc:

I repaired the last of the 3 faulty breakers on Tape drive 4 of CT, and also reconnected its broken wire that was starving a bunch of SMS cards from the -48V they deserved. Some more lights reappeared on the back neon debug panel as expected. I'm not sure if it fixed anything else. I tried to repeat the no-unload fault reported by the demo team, but it did unload (and load) normally. I don't know if I repaired it as a consequence of the breaker or if it's another intermittent fault that will soon reappear. I did not have time to look at CT tape #1 with the reported lazy reel, so that one was left to out of service.

We thought it was a good idea to place a keypunch outside of the barrier's in the 1401 room to be used by visitors when needed.

Sometime when the 1401 room was un-attended , the "A" key on that machine was broken.
Marc volunteered to take the keyboard home and see if he is able to fix it.

Aug 7, 2022, from Pat Buder, and (CT Tape addendum) from Jack Ghiselli
Sunday was the second day of the annual Vintage Computer Festival. We had a special Sunday demo at 11:00 with 44 visitors. Paul Laughton, Jack Ghiselli, and Mike Albaugh assisted. We were open all day and did mini demos for another 100+ guests from Switzerland, Netherlands, India, China, Ukraine, and the U.S.. The pace was somewhat slower than Saturday, but we still needed all four docents (there were five of us on Saturday).

We began the demo on CT. The BigPrint for one audience volunteer part worked well. However, we couldn't get Powers of Two to run. We switched to DE, but same problem. At one point, all four of us were pursuing fixes. We finally got it to work. It was a missing last card. We switched back to CT for the tape part of the demo because that was where we had prepped the tapes. We ran on drives #2 & #3. See Jackk's email for a detailed description of the problems on #1 & #4. One or two drives are sufficient for the demo.

The two 026's nearest the door ran fine. The 026 furthest from the door still has the stacker feed problem that we have documented previously. We didn't use the keypunch outside the rail. The sorter worked well.

We had a few reader checks on CT, but all resolved when the card(s) were read again.

At one point the CT 1403 again had the problem where one half of the page printed much more faintly than the other side. Firmly reseating the gate latch seemed to fix it.

During a slack period after the main demo, Jack ran his VOBJ program on several demo decks. It found missing cards, etc. which he fixed.

Unfortunately this was one of the most problematic demos I've seen. Many of the problems were actually operator errors. During the heat of running a demo with the associated time pressure it's easy to lose track of things. I would make these suggestions to help forestall these types of problems.

  1. Prepare both machines for potential use. This includes having a card weight, positioning the tapes, etc. After the demo the backup machine can be powered down.

  2. Have two verified copies of each demo program (BigPrint and Powers of Two). Create a separate date card for each BigPrint Place one of each program on the backup 1402 in case it is necessary to switch to the alternate machine.. Run all four of these decks before the demo.

  3. Remove all copies of the demo programs from the top of each 1402 except for the ones listed above.

  4. I asked Jack to begin marking the date each deck was verified on the first card rather than on a slip of paper that can easily become separated from the main deck.
VCF is by far our busiest event of the year. We have learned that five docents for Saturday and four for Sunday are needed. At non-peak times one of us is often elsewhere, e.g. gone to lunch, to visit the VCF, etc. Despite the long days and problems, VCF is very enjoyable. The technical sophistication of this group is greater than average, so the questions and interaction are better. We always look forward to VCF.


Aug 7, 2022, (CT Tape addendum) from Jack Ghiselli
Pat Buder was Lead on Sunday's demo, and will be submitting a report, expectantly upcoming soonly.

I volunteered to make this addendum report on the CT tape drives. Given all the hard work the Amazing Restoration Team has been doing on these tape drives, I'm embarrassed to report any problems, but here goes.

On CT 729 Tape Drive #1 (closest to the CPU), the tape media had a 3-inch long crinkly section a few feet following the start-of-tape marker. I cut the damaged length off the tape, and put on a new start-of-tape reflective spot. Problem fixed.

CT 729 Drive #1 also seems to have a problem with the feed reel. We use the TAU to command the tape to run, and it runs OK for a short while. Then, we observe that the feed reel sometimes doesn't keep up. When the free tape in the left-hand (feed side) vacuum column reaches the top vacuum hole, the feed reel is supposed to start moving and feed more loose tape into the vacuum column. However, sometimes we observe that feed reel is slow, so that the input tape goes farther and farther ABOVE the top vacuum hole. Eventually the entire feed loop is gone from the vacuum column, and the drive stops. The right-hand (take-up) side vacuum column is working correctly. We switched this drive to OUT OF SERVICE.

CT 729 Tape Drive #4 (closest to the entry door) refuses to unload. We switched it to OUT OF SERVICE, but after the demo we had to power down the CT 1401 with Tape #4 still loaded.

The demos ran just fine using 729 Tape Drives #2 and #3, so these are not serious problems.

--Jack Ghiselli, Cell 408-839-1051

Aug 6, 2022, from Jack Ghiselli
We gave the 1401 Demo Saturday 8/6/2022 during the Vintage Computer Fair, to a large group of 83 people. I was Lead and Pat Buder, Paul Laughton, Bill Worthington, and Steve Madsen were Assistants. After the main demo, we gave mini-demos to about 150 people, who kept coming by all afternoon. We had foreign visitors from Austria, Brazil (São Paulo), Canada (Toronto), Germany (Stuttgart), India (Delhi), Japan, Poland (Warsaw), and Russia.

We started using CT, but there were so many visitors we powered up DE as well. At first we couldn't get any decks to load on the DE 1402. Stan Paddock looked at it, waved his magic wand, and it healed, so we were able to use it. We had so many visitors we really needed all the docents -- they were all busy most of the time -- and both 1401's. We even used the 029 keypunch in the aisle.

The 1403 Printer on CT seemed to run out of ink, so the printeouts faded away. We fooled with it and the problem went away. Paul Laughton thinks the gate was not fully closed, so that the paper was not tight against the ribbon. We'll watch this tomorrow. The CT 1403 ran out of paper so we put in a new box, which turned out to be pure white, without bars; not a problem, just a surprise. 026 Keypunch #1 (farthest from the door) seems to have some problems moving cards to the output stacker -- Sometimes they hang up.

--Jack Ghiselli, Cell 408-839-1051

Ed Thelen here -

Jack's report (above) reminds me of stories of the last half of WWII in Europe -
Frequently, when adequate weather, the American Air Force would declare a "Maximum Effort Day".

If a plane could fly,
    It was in the sky,
        Over Germany

Looks like "we" are demoing "our" Vintage IBM 1401s
    "Maximum Effort"
        To the Vintage Computer Faire :--))

From Marc Verdiell

In my experience the CT does this inconsistent card loading consistently. It won’t pick anything, then all of a sudden it starts to pick the cards and it’s all good from there. I don’t think we ever figured out the problem. We should.

Aug 3, 2022, from Stan Paddock
Robert Garner 2.0
Frank King 6.0
Stan Paddock 6.0
Tom Szolyga 6.0
Frank continued work on the German 1402 card punch.
Frank thinks it is switch 41 on cam shaft 4.
He will test his theory next week.
Stan is continuing to work on the PC to IBM 029 keypunch in the Liebert room.
The first test passed two blank cards but no data.
Next week should bring significant progress.
Tom Szolyga
Today I did:
  • Figured out how to get ROPE3 to work with the LaserJet printer. Now I have it printing the ROPE listing in plain B/W, making them readable.
  • Sorted through the wires we harvested from the IBM cable/bisque connector to use in the harness for the NEW “Blue Box” I am building. My plan is to use twisted pairs for every signal between the 1401 and the Arduino. There will be a DB25 connector for input and another one for output of the Arduino. Each signal will use a pair of pins on the DB25. If the signals use the same bit ordering, it should be easy to find signals on the connectors. The extra grounds should improve reliability.
That’s all. See you in two weeks.
Best regards,

Aug 3, 2022 from Pat Buder
On Wednesday Paul Laughton and I gave the demo to 25 visitors. Another 15 came by before or after the demo. We ran on CT. All equipment ran well except as noted below.

CT Intermittent print problem:
Once when running BigPrint a person's name with a "D" printed as a "4" (missing zone punch). I checked that the card was punched correctly and it ran fine the second time. The card was punched on an 026, not the 001. I've seen this problem before but not recently. I discussed the problem with Frank King, who was there that day. He opined that it was not likely a printer problem or a reader problem due to the sum of punches error checking. No harm dome, but the guest wanted to keep both the erroneous and valid printouts. Extra special souvenir. I told him that the 1401 was very reliable back in the day and that we have to allow our Compusaurs a little leeway now.

Keypunch problem:
The 026 furthest from the door often only partially lifts the card into the stacker after it leaves the read station. Usually the card stops at an angle. It's easily extracted and handed to the guest. I'd say it happens 60-70% of the time.

On 8/6 before the crush of VCF visitors started I was duplicating "Decode Cards" (card with alphabet, digits, and most printable special characters) and had an opportunity to observe the problem a little more closely. I never use AutoFeed, but I do press REL/REG or REL/FEED rapidly in succession. I tried slowing down these steps, which seemed to help a little but not entirely eliminate the problem. The other two 026's worked fine.

As usual, thanks to Frank and the entire restoration team for keeping everything humming.


July 30, 2022, from Jack Ghiselli
Bill Worthington and I gave the 1401 demo today (Saturday 7/30) to 38 visitors, plus mini-demos for another 15 who came in later. We had foreign visitors from Switzerland (Basel) and the UK (London), plus various places in the US, including Hawaii, St. Louis MO, and Poughkeepsie NY (family of ex-IBM'er).

Kate, as you predicted in your email yesterday, your friend and donor Paula Golden apparently didn't show. However, Kate has lots of friends, so last Wednesday, your other friend Yi Ying, the artist from San Francisco did arrive and Pat and I had a pleasant talk with her. Yi taught me an important factoid: Where do Emoji's come from? Well, Yi apparently created artwork for an Emoji showing Boba Tea (if you don't know what this is, you're over 30). She then formally submitted it to the Unicode © Consortium, who accepted and registered it. It should appear on your smart phones soon.

We ran on CT which functioned perfectly, as did the 083 Sorter and all three 026 Keypunches. We didn't see problems with CT Tape #3 as Pat Buder had reported last Wednesday. The Restoration Team rocks!

Paul Laughton came in to take some photos for the upcoming 1401 Demo Docent training materials. We hope to give a new docent training session in the near future, if CHM can find some candidates.

A/V microphone #2 ran out of battery power at the end of the demo. We accidentally reloaded EBL batteries, and the mic went completely dead. We realized our mistake and re-reloaded disposable Energizer batteries and Mic #2 now works fine. All 1401 docents please note: The rechargeable "EBL" batteries do not work, and neither does the recharging unit. We have put two good-sized packages of disposable Energizer AA batteries in the A/V drawer; please use these for the microphones.

We had hoped to shunt 1401 demo visitors over to the PDP-1 SpaceWars competition starting at 12:00. Unfortunately, some hardware problems on the PDP-1 display forced cancellation. Hopefully it'll be rescheduled in the future.

We still need a 1401 Demo Assistant for this coming Wednesday 8/3. Then, Saturday and Sunday 8/6-8/7 we expect lots of visitors to 1401 demos during the Vintage Computer Fair. We could use at least three docents during those days. Poppy said she'd open up extra slots in the signup system.

--Jack Ghiselli, Cell 408-839-1051

July 27, 2022 - from Stan Paddock
Frank King 6.0
Stan Paddock 6.0
Tom Szolyga 6.0
Ken Shirriff 6.0
Marc Verdiell 6.0
Robert Garner 4.0
Ken and Marc
Ken started working on the CT tape read signals. Some channels are bad and we are getting errors from all the tapes.

Meanwhile I took apart and repaired the second breaker on tape #4. I think it had been worked on previously but the auxiliary contacts had been reassembled back together wrong. However nothing was broken, so reassembling it properly was all that was needed.

When I went to remove the third and last faulty breaker, I discovered that it was connected to a broken wire, with no matching other broken end for that wire attach to!

After some digging into the schematics, we figured out it was for a supplemental -48V power supply that is only present in the Phase II ans Phase III supplies. So at first we were not sure if it was actually needed. But we eventually figured out that we have a Phase III supply in the machine, therefore it’s needed. Ken figured out that it powers a section of SMS cards that drive the neon indicators on the panel at the back. So it does not affect the drive very much, just our ability to debug it.

I eventually found the other end of the wire, it had broken right at the bundle of cables that runs from the breakers to the rest of the machine, right at the sheath. I was able to unwrap a small section of the bundle and extract enough wire so we can reconnect it cleanly without running another wire. To be done next week.

Frank continued work on the German 1402 card punch.
Frank brought in his grandson Mason to help with the punch.
Rumor is that Mason did most of the work while Frank visited with visitors to the room.
He got the punch unit timed except of the shaft that drives PC CBs. It is close but not all the way.
Tom continued his work on the German PC connection in the workshop.
Stan continued his work to restore the PC to keypunch system in the Liebert Room.
Getting closer.


July 20, 2022 - from Stan Paddock
Frank King 6.0
Marc Verdiell 6.0

Frank continued work on the German 1402 card punch. He got the punch unit timed except of the shaft that drives PC CBs. It is close but not all the way.

A large number of visitors wandered into the 1401 room. While Frank is not comfortable talking to strangers, he played docent and told them about the IBM 1401.
[Ed Thelen here - Stan must be "pulling our leg" !! This is not the Frank King I know !! There is no way a person can call Frank "not comfortable talking to strangers".    ;--)) ]

This Wednesday, Frank mentioned that the breakers can be opened up and repaired, and that they had done so with many of them previously with Joe Preston. So I took one out (that's the hard part, as they have been soldered in), and indeed, you can open them up easily and repair them. I repaired the one that wouldn't trip (just freeing up and lightly oiling a lazy shaft), and put it back just in time for the 3:00 demo. Since I need to take the two other breakers out anyhow before changing them, I'll try to see if I can repair them too. I suspect it will be even easier, as they both trip but something is wrong with the low voltage contacts. Probably just cleaning the contacts will do. I'll let you know how it goes.


July 16, 2022 Demo, Saturday, from Jack Ghiselli
Bill Worthington and I gave the 1401 demo today to 38 visitors, and then mini-demos to 12 additional people who wandered in afterwards. We had foreign visitors from Australia, Canada, Korea, Russia, and Turkey. We also had some visitors from Omaha Nebraska, where I'm going to go visit next week (so I can't do the Saturday 7/23 demo), and they gave me some tips on what to see. Omaha is foreign lands to me.

We ran the demo on CT, using four (count, 'em, four) tape drives, thanks to the hard work from the Restoration Team. All CT, keypunch, and sorter hardware functioned perfectly.

Yesterday, I stopped by and repaired and verified three (3) BigPrint demo decks. These are in the Demo Tray, and have been verified 100% identical. Please use these. There are several other BigPrint decks kicking around (NOT in the demo tray) which don't work, and appear to be lacking cards at the end. Please don't use these until they've been repaired. There is one (1) Powers-Of-Two deck in the Demo Tray which seems to work.

I also duplicated several "Trojan cards" and put them in the Demo Tray. After repeated use, the first card of a deck sometimes gets a little frayed around the edges, and then won't load. You can put one or more Trojan cards at the front. They don't do anything except go to the next card, but they'll take the wear and tear away from the first card of the real deck.

Bill Worthington kindly helped me with researching exactly how the 1402 "End-of-Card" and Sense Switch A interact. Bill not only knows everything, he also knows where to find it in the manuals.

I managed to break the vacuum tube we've been using as a demo prop. I've been awarded "Klutz of the Day" for that. I found two smaller vacuum tubes which will probably suffice and put them in the demo box. If anybody has a (non-working OK) big vacuum tube, that would be great, since we try to show the size difference between the vacuum tube and a transistor.

Messing Up & sizes of vacuum tubes in archaic computers

Robert Garner has put a complete vacuum tube logic module (I think from an older IBM computer) in the 1401 demo box. It's very cool, but things get so busy during the demos that I'm deathly afraid I will damage this rare artifact. We'd all do well to handle it VERY carefully.

--Jack Ghiselli, Cell 408-839-1051

July 13, 2022 from Stan Paddock
Frank King 6.0
Stan Paddock 6.0
Tom Szolyga 6.0
Ken Shirriff 6.0
Marc Verdiell 6.0
Robert Garner 5.0
Bhushan Mohan --

Bhushan Mohan is a skilled IBM 1401 technician who visits upon occasions.
While he was here, He helped Marc and Ken work on the CT IBM 729 #4 as well as helping
Frank to debug the German IBM 1402 card punch.
Bhushan is welcome to come back and help us whenever he back in the neighborhood.


HI Stan,

Today I worked on 2 things:

New ribbon for Connecticut 1403

- German project

New Ribbon: I started by asking the status and the process for re-inking ribbons. First I learned no ink is put on the ribbon. Instead, the ribbon is sprayed with a liquid to bring ink in the ribbon cloth to the surface. Then the ribbon can print more pages. I learned that the guy who worked on the process passed away. We don’t seem to have the jig he created for the process or the exact recipe for the liquid. Next Robert found that we had a box of new ribbons. Stan pointed out it was no longer necessary to re-ink the ribbons. Thus a new ribbon was installed in the printer in time for the 3:00 PM demo today. The pages printed looked much better.

German project: I continued to develop the new PCwriter app. This app is in the PC and works with an app in the Arduino. On the PC, I implemented the command entry and decoding process. On the Arduino I implemented the command decoding process. In addition I put a looping structure around the app in both machines. This implements the shell for the rest of the apps implementation. The next step is to implement command execution processes in both apps. The PC app is using C++ under Microsoft Visual Studio. The process of translating portions of the existing app from C to C++ for the new app is ongoing. Since the SW is proceeding well, soon it will be time to build HW.

Best regards,



Marc and Ken teamed up on the #4 IBM 729 tape drive on the Connecticut system.

Now if you want to know what they did on Wednesday, view the following video.
Because the video file is large, it is slow to start.
Now if you want to know what they did on Wednesday, view the following video.
Because the video file is large, it is slow to start.


from Ken Shirriff, 7/16/20022

For future reference, here's how to diagnose the capstan switch problem from the indicator lights on the back of the tape drive. Either the Cap Out switch or the Cap In switch should be lit up (except while the capstans are moving). But we ended up with both lights off, indicating the capstan switch was messed up.


Stan continued to bring the Keypunch driven by a PC back to life.


Robert Garner helped getting things in order.


Wednesday July 13, 2022 - Demo Report from Mike Albaugh via Bill Worthinngton, an apology, two notes
Well, that was a fiasco. I did the demo solo, and not well. The sorter dumped all card into Reject, for several columns that clearly had punches in the selected column. It occurred to me driving home that "somebody messing with the row buttons" was perhaps a better explanation than "Evil Spirits in the clutch housing.

Tape problems were my own doing. Hwen I did the load/rewind, it ran off the end (was apparently already "to the right" of BOT. Then I muffed the re-threading... Even after I got it ok, I did not let it run long enough to hit the threshold for fast rewind.

Could not figure out how to keep the Mic from rotating down below my chin. Gave up and just yelled through my mask.

Did not pass artifacts through crowd. Enough problems already.

Did do Big Print for a kid who had "done it the hard way"

I feel like I'm in a spy novel and have returned to my desk to find a revolver with one cartridge, as encouragement.

OTOH, at least three people thanked me and raved about the Museum.

Again, apologies, although now I have given you several more ways to mess up the demo.


from Bill Worthington

Dear 1401 Demo Folks,

Mike very nicely did not mention that I was a strong contributor to the state of the demo today.
Mike, my apologies to you for missing being the 1401 Demo Assistant for today.

In a very partial defense,

  • Lame excuse #1: I am dealing with poison oak and am not wearing socks for another week. (I didn't want to be "out of uniform" for the demo.)
  • Lame excuse #2: I was researching a 1401 question for Jack Ghidelli.
  • Lame excuse #3: None.
Again to Mike, I'm sorry to have hung you out with no assistant. :-(

a note to all from Poppy Haralson,

All – Just wanted to let you know that a new monitor is on order and should be replaced within the week.

Thank you!
Poppy - Sr. Manager, Museum Services

another note from Poppy Haralson, Fri July 15

The new monitor has been installed and is working.

Please let us know if you notice any issues.

Thank you,


from Robert Garner

One of our happy visitors to the 1401 Demo Lab this afternoon came armed with her copy of 111 Places in Silicon Valley That You Must Not Miss.
It features the CHM and our 1401 Demo Lab as Place #35 on page 78, photos attached.

First published in 2015 and revised in June, 2021, here’s what it (incongruously) says about the 1401 Demo Lab: “Among the museum displays is an IBM 1401 Demo Lab, circa 1959, which lacks only a pencil-skirted secretary to bring to life.” SHUDDER.

It also reports on the CHM’s Babbage Difference Engine #2, “a steampunk masterpiece of cogs and levers.” OUCH.

Nice to have the publicity(!), but its CHM entry is shrieking for an update.

— Robert

p.s. About the Author on Amazon: "Floriana Petersen was born in Slovenia, where she studied Art History at University of Ljubljana. In 1986 she moved to San Francisco, where she finds illumination as an interior designer, art consultant, author, and photographer. Her interior design projects were published in numerous books and magazines (”

July 9, 2022 from Jack Ghiselli
Steve Madsen and I gave the 1401 Demo on Saturday 7/9 to 47 people. Today almost everybody was from the USA, with only one group from Canada.

We ran on CT which generally ran OK except that we got a few sporadic READ CHECK errors on the 1402. Reload corrected those problems. We powered up DE as a backup in case the READ CHECK problem persisted, but we didn't need to use it.

Same as Pat, we observed that the right-hand TV wall monitor has a bad display on the right 5 inch wide vertical column. Of course this doesn't affect the demos, since we turn off the TVs.

As usual, we had to try different BigPrint and Powers-of-Two decks to find ones that worked. I put a marker in the front of the good decks saying "Good 7/9". We still need to schedule a deck housecleaning, but I'm away for the next few days. Both Steve and I had to leave, so we didn't do any post-demo mini-demos today.

--Jack Ghiselli, Cell 408-839-1051

July 6, 2022 from Pat Buder
On Wednesday Bill Worthington and I gave the demo to 60 people, which included 20 high school students who joined us after the 2 pm Revolution tour. They didn't stay for much of the demo (bus to catch?). We also had 5-10 others for whom we did mini-demos before or after the main event.

We ran on DE, which performed well. After the demo when we were processing BigPrints, Bill switched to CT, which also ran well.

Stan came into the lab during the demo, so we had the audience give him a hand on behalf of the entire restoration team. He bowed graciously.

Problem (for CHM A/V):
The right wall monitor has an approximately 5 inch wide vertical area on the right side where the video appears hazy.

Note: I have been present for all Wednesday demos since we restarted them. I will NOT be available for next Wednesday, 7/13, so we will need both lead and assistant for that day.


July 6, 2022 from Ken Shirriff - CT #4 tape drive - suggestion from Iggy
Marc and I worked on the CT #4 tape drive today.
Summary: The drive still doesn't work and we found new issues. More investigation is needed.

The main question from last week was why did relay R109 burn out, and why is the replacement relay very hot. We determined that R109 is very hot on all the drives, so it's presumably working as intended and IBM just likes to keep things toasty. Marc checked that the voltage was correct, -48V.

We checked the circuit breakers and found that the -7.5V circuit breaker doesn't trip and reset. It should probably be repaired at some point. While looking at this, Marc noticed that there were disconnected wires on the circuit breakers, determined that they were for the fuse light, and fixed that.

We noticed that the right capstan was stuck halfway out. Fixing this didn't help overall.

Marc made a relay extender cable so he could probe the relays during operation. He found that the relays R107 and R109 appear to be operating properly so the problem must be elsewhere.

Current behavior:
When doing a load-rewind, the tape drive motors start, but then nothing happens. The next step is supposed to be the tape take-up motor lowers the tape into the columns, followed by the head descending and the capstans coming out, but these steps don't happen.

Hitting reset, unload causes relays to change state, but the drive ends up stuck in a semi-unloaded state where it will neither load nor unload. Setting R109 manually gets it out of this state, so another unsuccessful load-rewind can be performed.


suggestion from Iggy

Perhaps it may be a good idea to measure the current through that relays 109, 107, and the replaced resistor that was burned out…
Then compare against a drive that does not have the problem.
There’s a possibility of a wiring error, or a short in that rat’s nest area, with the close proximity of the wires inserted in the edge connectors.

Just my $0.02 worth.


July 2, 2022 - Demo, from Stephen Madsen & Jack Ghiselli, comment by Robert Garner
from Stephen Madsen

Jack Ghiselli and I gave a demo to 49 visitors. In addition to the local people, we had visitors from Japan, Australia, and Germany. We used CT, which ran fine. The sorter and key punches also worked fine. Thanks to the restoration team.

Stephen H. Madsen

from Jack Ghiselli

Hi Steve,
A pleasure working with you yesterday, as always. Again, you got through the main presentation in about 35 minutes flat. You are really efficient, and I'm going to try to learn from your presentation.
Just for your information,I stayed behind to continue my project to verify object decks. As usual, we kept getting late-arrival visitors continually coming in in small groups, so I had to break off and do mini-demos for them. It was a BUSY afternoon. I counted 58 additional people during the afternoon (after our main demo).

Wow. Anyway, in between I worked on BIGPRINT decks, running VOBJ to compare them, and repairing what errors I could. I ended up with three (3) good BIGPRINT Version 16.8 decks in the demo tray. Several others I discarded because of punch misaligned cards and other non-repairable errors. I hope to start on any other BIGPRINT decks are lying around, and on Powers-Of-2, and maybe LINCOLN.

--Jack Ghiselli, Cell 408-839-1051

from Robert Garner, Sunday 7/3/2022


Thanks for your steely quality control campaign!

— Robert

June 29, 2022 - from Stan Paddock, and others about Liebert air conditioner
Received from Stan Paddock Fri 7/1/2022. 9:06 PM

Status report Tuesday June 29
People who attended the CHM were:
X Stan Paddock 4.0
X Tom Szolyga 6.0
X Ken Shirriff 6.0
X Marc Verdiell 6.0
Ken Shirriff and Marc Verdiell went back to work on the number 4 tape drive on the Connecticut machione.
When they replaced the relay that was determine to be found, the tape worked for less than 50 seconds and failed.
In addition, the new relay became hotter than a two dollar pistol. (What ever that means.)

Suspect now switches is the circuitry that drives the relay.
Marc took home parts from the IBM 024 parts machine from the workshop in order to build a jumper to be able to measure the voltage and current of the relay that is failing

Next week we will again attack tape drive four.
Report from Tom Szolyga
Tom has now been able to communicate between the Arduino and an IBM PC over a single USB cable.
That is a big step forward tower communication between the German machine and an IBM PC.
Liebert heat problem
It was discovered that the Liebert air conditioning system had failed in 1/2 of it's capacity.
The question was is 1/2 of the Leibert is enough for our continued use?
Stan brought in a digital thermometer and turned on the German machine and the Connecticut at the same time.
Within a few minutes, the temperature dropped two degrees and stayed low the rest of the day.
This means CHM does not have to spend $12,000 to fix the failed part of the Leibert machine.
We will continue with the standard practice of turning on the Leibert when the German machine is powered up.

Stan Paddock

from Robert Garner to Stan Paddock - Wed 6/29/2022 11:32 PM


Thanks for your sensible insights and temp test today with our Liebert problem. I hadn’t realized/appreciated that it has two compressors (and evaporators).

From the Liebert manual..
… assuming our unit is the DH/VH199A model, it’s rated at 50kW (or 50/3.5 = 14 tons).

The manual notes: "The Deluxe System/3 is designed for maximum energy efficiency. Beginning with semi-hermetic compressors, the most reliable and energy efficient compressor available, Liebert adds an A-Frame coil that can provide 60% of total capacity with only one of the two compressors operating. Highly efficient fan motors pull air through the coil, providing not only better coil coverage, but reducing fan motor horsepower requirements."

Our two running 1401s (and the 60-to-50-Hz power converter) may dissipate about 20 kW(?).
so there’s not a whole lot of margin for a demo crowd if our Liebert can only handle 30kW with one compressor disabled.
(and it might be marginal on a hot day).

Perhaps we should ask the Liebert technician for his opinion?

Nevertheless, it does seem possible that we could permanently disable the failed compressor (to disable related error messages.
However, if the 2nd compressor starts acting up, then no demo’s until fixed (and a higher bill?)


— Robert

On Jun 29, 2022, at 10:02 PM, Stan Paddock wrote:


When I came in today, the temperature in the 1401 demo room was 76 degrees with the Connecticut 1401 on and the German 1401 and the Liebert turned.

I turned on the Liebert and the German 1401.

Within ten minutes, the temperature dropped two degrees.

For the rest of the afternoon including the 3:00 demonstration, the temperature stayed under the initial temperature.

It appears that the Libert single compressor test was a success.


>> ---------- Forwarded message ---------
>> From: Gary Matsushita
>> Date: Tue, Jun 28, 2022 at 8:27 AM
>> Subject: RE: Liebert Machine
>> To: Stan Paddock
>> Hi Stan
>> Thanks for the input. If your 1401 team reviews and feels this is the move that is best for the next step, they can let Collections/Exhibitions (Dag/Kirsten) that this might be best use for the exhibit on-going. What was set up with the two Lieberts dates back to the room build-out, and the placement & use of the Lieberts was from the 1401 team. Changing if your solution is better makes sense. Re funds, there was very little still remaining for the 1401 project (a couple thousand max), so Exhibitions was going to have to pull from its general funds to do the repair. I’m sure they will be happy with a less costly fix!

From: Stan Paddock
Sent: Saturday, June 25, 2022 8:54 PM
To: Gary Matsushita
Subject: Liebert Machine


The Computer History Museum gained a bunch when they purchased 1401 Shoreline Blvd.

As the corporate headquarters for SGI, the building came with a large computer room with a raised floor, a large UPS (Uninterpretable Power Supply), a large generator in the parking lot and a large Liebert air conditioner.

We had no need for the UPS or the generator in the parking lot and have been removed.

The Connecticut IBM 1401 consumes 12 kilowatts when in operation without requiring any external air conditioning.

The German IBM 1401 also consumes 12 kilowatts when operational and an additional 12 kilowatts with the 60 cycle to 50 cycle power converter operational.

Our operation guideline is that if the German machine is turned on, turn on the Liebert air condition,

Without doing this, the room gets warm within 15 minutes.

The Liebert is a monster with two systems inside.

It was designed to handle a room full of computers when SGI occupied the building.

The current problem is that one of the systems inside of the box has leaked its entire supply of R-22 refrigerant.

According to the Liebert service technician, it is ok to run the Liebert on one system.

Might I suggest we run the Connecticut IBM 1401 and the German IBM 1401 at the same time with the Liebert running 50% capability to see if that is sufficient air conditioning for operation.

If this works, you could have the Liebert service people wire the Liebert to run as a single system.

Then you will only get an error message if the single system develops an error.
This will cost far less than the $12,000 it will cost to fix both systems.

Stan Paddock

June 29, 2022 - demos, Wednesday, from Jack Ghiselli
On Wednesday 6/29, Pat Buder and I started verifying demo decks.

1. BigPrint. We found the current version is 16.8, generated 3/18/2016. This identifier can be found in object cards 7-8. In the ROPE compiled object deck, there is a one-byte error in character maps. The result is that the character "D" has undesired spaces when rendered as middle- or large-size. The correction is to patch object card #98, column 28, from a "4" to an "8". Here is the printout symptom:

In the patched card #98, we added the comment "PATCH" in an unused area (column 30 ff), to remind ourselves in the future. We also ran VOBJ to verify one other copy of BigPrint. Another copy of BigPrint had so many errors we trashed it.

2. Powers-Of-2. We found our demo deck had one card out of sequence. Although this was not a fatal error, we moved the out-of-place card into correct sequence.

Tomorrow (Thursday 6/30) afternoon Poppy has scheduled 100 high school students to visit, and we will give them a 1401 demo. If we have extra time, we will try to verify some additional demo decks.

--Jack Ghiselli, Cell 408-839-1051

from Robert Garner - Wednesday, June 29, 2022 10:59 PM


You’re genuinely disciplined in the IBM way. :)

We need to THINK about a bonus/salary raise! :))

— Robert

June 25, 2022 - demos, Saturday, from Jack Ghiselli, June 26 added comment from Frank King
026 Keypunch #2 unjammed
Bill Worthington and I gave the 1401 Demo today to 35 visitors. We used CT which worked perfectly. Only the 4th Tape Drive is still unavailable, and that is no problem for the demos. Yay, Restoration Team!

026 Keypunch #2 is still unusable. (See update :--)) When powered on, the drum continuously rocks back and forth. Something is jammed. We tried moving the cover around (which helped in the past), but no joy. When we have large groups, three keypunches really helps.

Everybody should take a turn working with Bill Worthington. That dude has been squared away by 10000 years working for IBM. Bill says at end-of-day in an IBM office you had to clean everything off your deck top and leave it pristine! So, today first thing he did was find the horseshoe key-ring I'd misplaced last Wednesday. Next, he whips out a NEW CARDBOARD BOX he's brought to hold all the demo props. Since we're a museum, we probably should have had Dag Spicer there to curate the century-old previous cardboard, but what we did was THROW IT AWAY, and clean out the heap of trash at the bottom and reorganize. We discovered the two demo SMS boards which I thought had been stolen, so we're back to seven. And the scissors, which we returned to the tool chest "knives" drawer. And a whole bunch of card weights, which we returned to the rack in the back room (the demo box now has exactly 5 card weights: 083 Sorter, CT reader/punch, DE reader/punch). Much easier to find things now. Bill says the new box was originally used by his grandfather, Reverend Worthington, so the contents are now blessed.

Now that the CT 1402 punch works, our next objective is to clean up the various decks in the Demo Tray. I ran VOBJ on the BigPrint and Powers-Of-2 decks we've been using, and found a couple of innocuous errors, but the decks still run OK. I wrapped printouts of the problems around the BigPrint and Powers-Of-2 in the Demo Tray, if you're interested. I started on some of the other decks and found they were missing cards, and/or shuffled. There's also a copy of VOBJ and operating instructions in the Demo Tray.

But, we had a constant stream of late visitors after the main demo had completed at noon, lasting almost until 5:00 pm. When visitors come from far away, and are here only for the day, you feel you need to stop and talk to them. We gave mini-demos after the main demo to small groups totaling 52 people. Maybe we should schedule a Monday or Tuesday to spend time reviewing demo decks when there are no visitors?

We had overseas visitors from Australia (Sydney), Bangladesh, Belarus, Brazil ( São Paulo Salvador), Canada (Waterloo), China (Chengdu), Peru, and Russia (Moscow). Also an interesting group of aeronautical engineers from Joby Aviation, a local developer of autonomous electric VTOL craft.

--Jack Ghiselli, Cell 408-839-1051

From Frank King, Sunday June 26

Hi, I always love these reports. Thanks Jack
I think I have a fix for Key Punch # 2. The back space key is jammed down, I think.
Remove the cover and pull it back up. If the cap comes off you may need to pull it back up with a pair of pliers. It is probably bent and needs a gentle touch.
If it is still bad Wednesday, I will fix it. Good Luck. :-)

Frank King

(See update :--)) dated 11:19 AM Wed 6//29/2022

From Ken Shirriff

I unjammed the backspace key following Frank's advice and keypunch #2 now works.


- - - - - - -

From Jack Ghiselli - June 29, 2022 11:46 AM

Thanks, Ken. That will help the demo today. Sorry we couldn't fix it ourselves.

June 22, 2022 - demos, Wednesday, from Jack Ghiselli
Hooray to the restoration team! Yesterday (Tuesday) Dale Jelsema, Frank King, Mason King, and Stan Paddock fixed the CT 1402 card punch, which has been down for a couple months.

I came in yesterday and punched some ROPE object decks which had been waiting on the 1402. One is the VOBJ verifier to help check if our demo decks have any problems. I punched its object deck and rant it, and sure enough, it showed some minor errors in both our demo-copy BigPrint and Powers-Of-2 decks (but they run).

The Wednesday 3:00 demo was so popular it ran until almost 5:00, so we didn't have much time. When we get more time, we'll check all the copies of all the demo decks.

Thanks again to the Restoration Team.

--Jack Ghiselli -, Cell 408-839-1051

June 21 & 22, 2022
from Stan Paddock, June 22th
Report from Tom Szolyga
Today I worked on the SW to communicate between the PC and the Arduino.
Making progress.

From: Ken Shirriff
Marc and I looked at the CT tape drive problems today.
Last week we found an exploded resistor-capacitor module RC108 on tape drive #4 and Marc removed it with great difficulty:
Marc tested it on his fancy HP RLC machine and surprisingly it turned out to work just fine! So we took a closer look at latching relay R109 next to it:
As you can see, the relay coil shorted out. Apparently the heat from this damaged the case of the RC module next to it.

I found three replacement latching relays in the workshop. One looked like it had been underwater (extensive rust), one had a bent contact that wasn't closing (not the contact wire that moves, but the U-shaped fixed part was bent), and one had some dirty contacts. Marc is cleaning up the contacts and we'll replace the relay next time.

Second tape drive issue.

A few weeks ago, Frank and Stan noticed that the CT tape drives gave errors almost continuously when operated from the TAU control panel.
I looked at the bit signals on the CT machine and compared them with the DE machine.
On the DE machine, the signals from the tape drive are 8 volts peak-to-peak as they should be.
On the CT machine, the levels were all over the place.
Here's a look at tape signals on the DE machine:
The yellow line is the raw signal from the tape drive, 8 volts peak-to-peak.
The cyan line shows the signal after rectification, so it has twice as many peaks.
The pink line shows the signal after differentiation, producing spikes.
Finally, the blue line shows the data as stored in the TAU bit latch.

On CT#1, when all bits were supposed to be set, bits 2 and C were missing from the A register.
That is, the TAU didn't read these bits.
Here's how bits 1 2 4 and 8 look as received from CT drive 1.
These should all look like the yellow line above.
Note that bit 2 (cyan) is about 3 volts peak-to-peak, much lower than the others, which would explain why it doesn't get read.

The others are 6 volts instead of 8, so they are significantly lower than they should be, but the TAU still mostly reads them. I didn't look at bit C, but it's probably low like bit 2.
Probably the amplifiers need to be adjusted, although it could be a problem with writing instead.

Drive #2 is even worse, with all the signals around 2 volts peak-to-peak.

Drive #3 has signals around 5 volts peak-to-peak.

I didn't test drive #4 because of the relay problems.

Since the drives all have different issues, I think the problem is with the drives, not with the termination.
So it looks like the CT tape drives all need some adjustment before they will read data reliably.


From Marc Verdiell

And while Ken figured out the bad relay and the bad tape reads, I replaced the cracked RC module with one that looked good (although, as Ken pointed out, the cracked one probably still works, it appears to be just cosmetic damage).

I think we should reverse engineer the cracked module construction for the benefit of science, it looks like a highly interesting and advanced construction, maybe using thin film ceramics.

I then proceeded to reconnect all the backplane wires at the right places, those that I removed on purpose and had marked, and those that had decided to remove themselves on their own will without being marked.

It’s very hard to access and see through the thick mess of entangled wires in the backplane, and I was proceeding quite carefully to avoid introducing wiring mistakes, so that took me all day.

All the wires are back in, hopefully on the correct pins.
We should be able to just plug in a new cleaned-up relay in location 109 next week and see if we corrected the problem.
Or if we created a new exciting one…


from Stan Paddock, June 21th

Frank King has a grandson Mason King who came in today to see what his grand father does at the CHM.
Mason was a great help with today's work on the punch.

Connecticut IBM 1402 Card Punch

For several weeks, we have tried to fix the card registration of the cards punched on the Connecticut machine.
We have tried cleaning and adjusting this and that.
We have three books on maintaining the 1402 card punch.
None of these books seem to match our punch.
One of the books seemed to be close to our punch.
It described an adjustment that has a range of +- one degree.
When the guys checked, it seemed the adjustment was out of range.
Frank, Dale and Mason adjusted the setting and it fixed the problem!!
With the knowledge from fixing the Connecticut card punch, we think it is time to fix the card punch on the German card punch next punch.

Leibert room PC to IBM 029 keypunch

Stan is continuing to change the software to support the new hardware configuration.
Several weeks to finish the job.


------------ This is an addition from Frank King in reference today's work. ------------

We cleaned and adjusted the timing on the grip and release, of the secondary alignment for the card to be punched.
We reproduced a new big print card deck and left it on the reader.
I hope this fixed the problems with the punch unit.
You guys can try it out and let me know your results.

Thanks for all you do.

Present were:

Dale Jelsema
Frank King
Mason King
Stan Paddock

June 14 & 15, 2022
from Stan Paddock, likely June 14th
Ken Shirriff is well known for reverse engineering printed circuits.

He found that there is a relay in the third IBM 729 on the Connecticut machine that was not playing along with the band.
Ken took the SMS card that drove the relay home and checked the driver circuitry that drove the relay and found the transistor that drove the relay was blown.

Ken replaced the SMS card at the CHM and tried it again.
he relay stilled did not work.
Not only that, the same transistor as before was blown.

This narrowed the problem down to the relay or the arc suppression diode across the relay coil.

Failure of either one of these is very rare.
The arc suppression diode had shorted so that when the transistor wanted to activated the relay, the shorted diode blew the transistor.

In the shop, we have multiple copies of the transistor so both blown transistors were replaced.
Marc found a generic diode that had a higher PIV and current rating than the original diode.
With a little soldering, the tape drive was put back together and tested.
Everything on drive three is AOK.


Reports from Tom Szolyga and Ken Shirriff via Stan Paddock, June 15th

Today I {Tom} worked on the SW to communicate between the PC and the Arduino.
Making progress.

Stan, here's Ken's Wednesday status explaining the RC module problem.

I investigated the tape drive CT#4 more today and it needs a new RC 108 module. This resistor-capacitor module snubs the relay coil. As you can see in the photo, it has self-destructed. (This is the module to the right of relay 107.)
Click to enlarge

To summarize what I've found:
Latching relay 109 closes to indicate an unloaded state. (It latches to store this state across power off.)
When this relay opens, it turns on the blower relay DP4.
When the blower vacuum switch closes, it turns on the main run relay R1.

The observed problem is that when the drive is powered on, the blower turns on and then the drive starts running, even though it is unloaded. So the problem is in the R109, DP4 path. I figured one of these relays might be faulty. However, the bad resistor-capacitor module R108 is across the coil of R109, so if it's messed up, it would explain the problem.

I need help to replace the RC module though:
  1. Do we have any of these 330 ohm .1 mfd modules?
  2. The module is hard to replace; it has taper pins plugged into it, and of course they are behind a bunch of wiring cables. So I'll need a hand with the wiring.

Click to enlarge
There's nobody else in today, so we can work on this next week.

Also, about 30 people came through the lab and I explained the computers.
The computers weren't powered up, so I couldn't do demos apart from the manual punch

June 11, 2022, from Jack Ghiselli
Bill Worthington and I gave the 1401 demo to 38 visitors, plus 11 more afterwards for mini-demos. Special thanks to Jesse Nichols who went through Revolution and urged visitors to come to the 1401 demo. We had foreign visitors from China, Ireland, UK (London), and Italy (Calabria). Our timing ran a little long (45 minutes). We ran on CT, and all hardware worked perfectly. CT 729 Tape Drive #1 seems not to do high-speed rewind, but stays in low-speed. That doesn't affect the demo, though.

We had apparently used up almost all the non-rechargeable AA batteries for the microphones, so I brought in a couple additional packs. We should have enough for several months now.

--Jack Ghiselli, Cell 408-839-1051

June 7, 2022, from Stan Paddock and Robert Garner
from Stan Paddock
When we came into the 1401 demo lab, we noticed 4 things that need our attention:
  1. The third tape on the Connecticut machine was partially loaded and the tape was cut.
       Ken took the reel down, cut the damage portion of the tape off and added a new beginning-of-tape on the tape.
  2. We configured the first tape drives as 1,2,3 and ran them from the TAU and got errors from each tape.
       Ken said Marc was working with these tapes and the configuration with the terminator and may know what is going on.
  3. Tape 4 was know to be out of operation.
       What Ken discovered is that when the tape is powered up, it goes into a status of 50% up and 50% down.
       It is not obvious what is going on.
        Ken took home books on the tape drive to learn what make the tape work.
  4. Frank and Stan checked out the card punch on the Connecticut system.
       Last week we pulled the punch unit, Cleaned every thing and put it back together.
       We punched some cards and discovered we had not fixed the problem.
        We also noticed that a pair of lower bearing are very worn.
       We will try to remove the roller shaft and get to the bearings.

e-mail from Robert Garner to CHM facility folks, June 8

Gary, Dennis, Poppy, et al,

Per Jack Ghiselli's May 28th email below, the Liebert in the 1401 demo lab is in need of service.
I understand that a Liebert field engineer checked it out a couple of weeks ago and may have concluded that one of the (two) compressors was faulty.

Any news on the repair status? Or plan for getting it repaired?


— Robert

p.s. Someone had tuned Off the main On/Off lever switch. I turned it back on for this afternoon’s demo.
When both on, the 1401 units and the 60-to-50-Hz power converter combined can dissipate up to 25kW of heat.
If not removed, it can get too warm during the 1401 demos and maintenance sessions.

From Marc Verdiell

If I remember correctly, a technician came last week. One of the two systems was out of refrigerant. It must have a leak. The refrigerant was replenished and the system was repressurized, but that is a temporary repair. The technician recommended that a proper leak detection should be made in a subsequent visit and the leaky part replaced. Not sure who is in charge of that at the Museum (facilities?).


from Luis Valencia, Facilities Manager, Computer History Museum

Hello All
As of right now Facilities is waiting on repair proposal from ACCO.
We’ll keep everyone posted on this.

Thank you,

June 4, 2022, from Jack Ghiselli
I gave the 1401 Demo today, Saturday 6/4/2022. Steve Madsen had kindly signed up to help, but at the last minute had a conflict.

I suspect the nefarious Amazing Restoration Team is having fun teasing us demo docents. When I powered up CT, at first the 1402 wouldn't read cards, although I tried several decks. Finally opened up the covers and lo to my surprise found a greasy paper towel in the read rollers. I bet you guys have a camera somewhere and were just laughing at us. OK, I have put the greasy paper towel SOMEWHERE in the maintenance area -- you find it! After that, all hardware worked perfectly -- the CT, its first two 079 tape drives, all the 026 Keypunches, and the 083 Sorter. Anyway, if you guys fix the CT 1402 punch, all will be forgiven.

We had a lot of visitors -- 42 for the main demo, and 36 others who wandered by later in small groups for mini-demos. We continue to get quite a few international visitors, today from Australia (Melbourne), India, Kazakhstan (Almaty), Switzerland (Zurich), and Uruguay. With only one docent, the after-demo BigPrints and especially the mini-demos for later groups went slowly. We try to shut down after the main demo, but it's really hard to turn away a visitor who's traveled a long way, with only today to see things. So mini-demos went on until 2:00 PM.

I had to remind a few visitors that the CHM is requiring masks for 1401 demos. The front desk has extras.

--Jack Ghiselli, Cell 408-839-1051

Addendum -

Well, Ed, there was GREASE on that towel. We demo docents mostly just stand around looking beautiful. I had to go wash my hands. Yuck!

May 31 & June 1, 2022
from Stan Paddock
Status report Tuesday May 31
from Stan Paddock

Ken Shirriff is well known for reverse engineering printed circuits.
He found that there is a relay in the third IBM 729 on the Connecticut machine that was not playing along with the band.
Ken took the SMS card that drove the relay home and checked the driver circuitry that drove the relay and found the transistor that drove the relay was blown.

Ken replaced the SMS card at the CHM and tried it again.
The relay stilled did not work.
Not only that, the same transistor as before was blown.

This narrowed the problem down to the relay or the arc suppression diode across the relay coil.

Failure of either one of these is very rare.
The arc suppression diode had shorted so that when the transistor wanted to activated the relay, the shorted diode blew the transistor.

In the shop, we have multiple copies of the transistor so both blown transistors were replaced.
Marc found a generic diode that had a higher PIV and current rating than the original diode.
With a little soldering, the tape drive was put back together and tested.
Everything on drive three is AOK.

Having three operation IBM 729 tape drives on one 1401 computer is pretty good.

Next week we will attack tape drive four.

Status report Wednesday June 1
from Stan Paddock

People who attended the CHM were:

Report from Tom Szolyga
Today I worked on the SW to communicate between the PC and the Arduino.
Making progress.

The 1402 card punch on the Connecticut machine had decided to start punching cards out of registration.
Today, Frank King and Stan Paddock pulled the punch out of the Connecticut 1402.
This allowed us to clean and lubricate the internals.
The timing was checked.
We will put everything back together next week and test the operation.
Next Tuesday, Frank and I will complete the re-installation and testing of the punch.

The German machine runs on 50 cycle power.
This requires an 60 cycle to 50 cycle power converter in order to operate.
The power of the 60 cycle to 50 cycle power converter and the power of the German machine generates more heat than the standard air conditioning can handle.
When running the German machine, the Liebert Air conditioner has to be on to dissipate the heat.

The docents noticed an error displayed on the Leibert air conditioner in the back room.
They passed the error on the CHM staff and a Liebert serviceman came out today.
The serviceman told us that the machine can be used as is until they can come out to fix the problem.

Robert Garner invited guests to the CHM today.
His guests today were Geoff Thompson, Ron Rider, John Shoch, and Dan Swinehart, from the early days of Xerox PARC, 1972-74. 1
I believe they liked the IBM 1401 exhibit more than the rest of the CHM.


1 from: Robert Garner
To those interested/involved in Ethernet's history,

Here's the YouTube recording of the April 13th “Ethernet’s Emergence from Xerox PARC” IEEE webinar: (about 2.5 hours)
Click Here for time sequence of speaker and topic

May 28, 2022, from Jack Ghiselli
NOTE: The Liebert air-conditioner unit in the back room is sounding an audible beep, and its tiny screen is displaying the error message
Turning the Liebert off and then back on makes this message go away briefly, but it soon reappears. I hope somebody more competent than me can look at the Liebert and see if it needs fixing.

Today, Steve Madsen and I gave the 1401 demo to 43 people, and mini demos to 10 additional people who wandered in later. There were visitors from Connecticut, whom we told about the history of the CT machine, and two separate families from Germany (Bremen and Hamburg) whom we told about the DE machine (they liked the internal 1403 labels in German). Another group came from India (Bangalore), and we showed them the photo of the (non-functional) IBM 1401 on display in Bangalore, which they now intend to go visit. There were also international visitors from Russia (two different people) and Switzerland (Zurich). The museum seems to be attracting lots of overseas visitors.

A BIG thanks to Steve, who signed up to assist at the last minute when he noticed nobody else had. Yay, Steve! We finished the demo in 40 minutes time, and got all the after-demo BigPrints done and handed out to this large group by noon. We used CT. All the hardware worked well, including all 029 Keypunches and the 083 Sorter. On the 083, we are using Pat Buder's suggestion to alternate between columns 74 and 75 on the Sort Deck, which seems to result in a pleasing Sort demo. Thanks to the Restoration Team's work last Wednesday, two 729 Tape Drives on CT were working so we could demo tapes using the TAU.

As a reminder, the CHM is asking 1401 demonstrators to require masks on all visitors and demonstrators in the 1401 lab.

Stan: I forgetfully left my USB thumb drive in your PC hooked to CT. Please don't throw it out, and I'll get it next time I come in. PCWRITE function 2 works great for printing ROPE listings on 14x11 paper.

May 24 & 25, 2022, from Ken Shirriff, Stan Paddock, Robert Garner, and Antoine Bercovici
from Ken Shiriff via Stan Paddock - May 24

Ken worked 6 hours
I was the only one at the lab today, so I studied the documentation for the CT drive that isn't loading properly. I didn't power up the system since I figured that poking around in the tape drive by myself was potentially hazardous.

Summary: I think the problem is that the capstan motor isn't starting. I hope to probe the capstan motor logic (TU.9.40.1) tomorrow.

Details (mostly for my reference, but in case anyone wants more):

To review, the symptoms when loading a tape on this drive:

  1. The tape down motor goes on for a few seconds and stops. This turns the worm gear that rotates the brake clutches, moving the tape slightly into the columns. This behavior is correct.
  2. The head up motor moves the head down (down, not up, because R7 motor reverse is active). The head up switch opens and the head down switch closes as expected. However, the motor doesn't stop, which is wrong.
  3. The capstans don't come out, and the right clutch doesn't spin the tape into the column. This is also wrong.
I think that figuring out why the capstan motor doesn't start is the key, since the clutch is activated by the capstans. The capstan logic is TU.9.20.1:
The capstans depend on a bunch of signals: R7 motor reverse, LD rewind stat, tape in L col, tape in R col, unload status, and head down. The tape in column signals are supposed to be the ones that cause it to activate. They looked okay when I looked on the oscilloscope a couple of weeks ago, as did the head down switch. So maybe another signal is messed up, or a board is bad here, or there's something wrong with relay R3 or the capstan motor. I hope to probe these signals tomorrow which with luck will make the problem obvious.
As far as why the head down motor doesn't stop, I've puzzled over the logic for a long time. My conclusion is that the logic doesn't match the written description in the manual:
Supposedly the head down switch stops the motor, but as far as I can tell, this is not how the logic is implemented and not how this 729 should behave. My guess is that this 729 is a bit unusual (since it's the only one with this circuitry in the lab). Specifically, on TU.09.35.1, unload gate goes low, which blocks the signal from head down and then ld gate, so the motor stop signal is blocked. All the signals here appear "correct". As far as I can tell, the circuit just doesn't match the description, and the motor is not stopped by the head down switch.
My theory is that this drive is designed so the head down motor will be stopped when the capstans move, rather than when the head down switch closes. (The logic supports this.) Since the capstans aren't activated (due to the problem), the head down motor will keep running, which we see.

Thus, fixing the capstans should make everything else work.


Status report Wednesday May 25 from Stan Paddock
People who attended the CHM were:
Ken Shirriff6.0
Report from Tom Szolyga

Project Report: Today I worked on the SW to communicate between the PC and the Arduino. I have converted the PCWriter app to Visual C++ and Visual Studio 22. It compiles and runs on Windows 10 or 11. So far it takes commands from the user and opens/reads and writes files. Next step is sending the files to the Arduino. I am investigating two ways to do that. One way is by doing IN or OUT instructions to the I/O port. The second way is by using Windows I/O functions calls. Doing I/O instructions in a C user application program to a Serial port mapped through a USB port is dodgy because Windows is not a real time system. I am thinking that using Windows function calls is a more definite, easier to read approach. Unfortunately it takes more time and effort to create.

Report from Frank King

Ken and I worked on CT tape drive # 3. The head down switch seems to be operating properly but the circuit that starts the capstan motors doesn’t seem to be working. If we manually pick relay 3, the capstan motors start but the circuit doesn’t pick R 3 or R to 8 like it is suppose to. Ken is going to take the card home to see if there are bad transistors.

and Stan

I duplicated Big Print deck using CT and it ran ok except for one reader check. So, we should make the alignment of the punch a priority next Tuesday.

Mark and a buddy from Paris (Antoin Bercuvri), I think, continued body work on the covers for the tape drives. Looks like they knew what they were doing.
They fit for the first time. :-)

Robert showed up for a few minutes at lunch and then came by the 1401 area for a short time.

We had a visit from Kate McGregor.
She stopped by on her way from Alaska.
What a wonderful person.
The Museum was lucky to find her.
Too bad she has to work remotely.


From Robert Garner

Attached are four photos of Marc & Ken working on the ailing CT 729s with Marc's guest Antoine Bercovici visiting from Paris yesterday!
It was fun showing off/sharing the 1401, RAMAC, and Revolution exhibits with Antoine.

In his spare time, Antoine has beautifully micro-photographed hundreds of chips (from his collection of thousands):
His "day job" is researching paleolandscapes, paleobotany, and sedimentology:
(I dare say that integrated circuits could be viewed as an instance of small-scale sedimentology! :))

From Antoine Bercovici

Adding my own shots of the day, this working 1401 display is some of the most unique vintage computer exhibit, having all the sound and the smell of the vintage equipment filling the room.

I must say that Zeptobars is not me, but as well as is!

And a bit of shameless promotion for our work in Colorado, elucidating how life recovered in the 1 million year following the dinosaur killing asteroid impact:


Dr. Antoine D. Bercovici
Research Associate (Paleobotany and sedimentology)
Department of Paleobiology, NMNH Smithsonian Institution
10th Street and Constitution Ave. NW, Washington, DC 20560-0121

May 21, 2022
from Jack Ghiselli

I gave the 1401 demo on Saturday 5/21. Nobody signed up as Assistant. There were 32 visitors for the main demo, and 19 people who wandered in later for mini-demos. There were international visitors from Australia (Sydney), Canada (Vancouver), Germany (Hamburg), Poland (Warsaw), Russia, and Switzerland (Zurich). A very lively group, with lots of questions. I used CT, which worked perfectly. The Amazing Restoration Team had even got one CT tape drive working, so there was no need to use DE for the tape demo. All 029 Keypunches and the 083 Sorter worked perfectly.

I put a good BigPrint deck and a good Powers-Of-Two deck at the front of the metal Demo Cart tray, and recommend you use these. There are several other copies which don't work, and a quick inspection showed at least one was missing cards. I'm looking forward to a working 1402 punch so we can punch a new VOBJ object deck, run it to see what the problems with the various Demo decks are, and make all copies good.

The main demo, including 083 Sorter, took only 37 minutes, which is about the desired duration. Without an Assistant, the multiple after-demo BigPrints took longer than usual. One minor good news item: I discovered our missing third demo vial of cores at the bottom of the cardboard carton on the Demo Cart, so it didn't get stolen after all. Thank you, Esteemed Honest Visitors. "Trust but Verify", as Ronald Reagan used to say, quoting the old Russian proverb, “doveryai no proveryai”.

--Jack Ghiselli, Cell 408-839-1051

May 18, 2022
from Bill Worthington

On Wednesday, May 18, Pat Buder and I conducted the 1401 demo for 14 museum visitors. They were joined about 5 minutes after the demo started by a dozen highschoolers who were enjoying a field trip. along with the 14 visitors was a couple from Italy.

We had a problem finding a working BIG PRINT deck(I thought there were about 3 copies in the program tray.and borrowed Jack Ghidelli's Thanks Jack!

May 17 & 18, 2022, from Stan Paddock
May 17
People who attended the CHM were:
Stan Paddock 6.0
Marc Verdiell 6.0
Stan worked on the CT 1402 punch. I cleaned the feed rollers and lubricated the feed rollers bearings. While everything looked better, it did not fix the registration problem. Marc and I discussed how to put the CTE tape drive back together.
May 18
People who attended the CHM were:
Stan Paddock 6.0
Tom Szolyga 6.0
Marc Verdiell 6.0
Tom was continuing his work on the new German PC connection and said he was making progress.
When I came in, Marc was attempting to mount the front door of the first tape drive with the help of Dale Jelesma.
Dale is a friend of Frank King and worked for IBM for over 40 years.
We are glad to have Dale join us when he can.

Marc and Dale worked on the tape drive getting all the sheet metal reattached to the drive.
It took the skills of a body shop to get the covers to fit back on the machine.
That tape drive is now fully operational.

Stan worked on the punch for the CTE machine.
The punch produces cards that are out of registration.
The work I did not fix the punch.
Where is Frank when you need him?

May 14, 2022 - from Jack Ghiselli
Paul Laughton, Ken Ross and I gave the 1401 Demo on Saturday 5/14. I was Lead, and Paul and Ken decided Ken would be the Beautiful Assistant. I have to say I couldn't decide who was more Beautiful, but Paul was about to travel out of town so decided he'd not expose himself to COVID. We had two visitors early, 18 people for the main demo, and 20 wandering in afterwards for mini-demos. Today it was a smaller group of visitors, but quite varied -- we had visitors from Australia (Perth, no less), Bulgaria, Chile, Italy, The Netherlands, and Thailand. We tried to remember to use metric measures during the presentation, since real-world visitors get annoyed at inches, yards, hogsheads, etc.

The visitor from Bulgaria had worked back in 1968 on punch card computers built in the Soviet Union, which he said were copies of IBM 360s.

When we came in, there was a multi-card jam in the 083 Sorter. I had missed seeing Pat Buder's report from Wednesday about this, but luckily we were early, so had time to clear the jam and get the 083 running again. While testing the 083, I noticed that cards were sorting into the correct 0 to 9 pockets, not "one off" as in the past. The 083 directed some cards to the REJECT stacker, although the cards seemed to have good punches. I suspect some of these had been punched sightly mis-aligned, so I'm not sure whether our past sorting problem is actually an 083 problem or a 1402 punch alignment problem. I agree with Pat Buder's suggestion that after the 1402 Punch is fixed we should punch a new demo Sort Deck.

We ran the demo on CT, but since none of its tapes are working yet, we demonstrated 729 Tapes on DE, using the TAU. Everything ran beautifully. Thank you again, Restoration Team. We got the demo finished in 45 minutes, which is slightly long. Still working to shorten it up.

--Jack Ghiselli, Cell 408-839-1051

May 11, 2022
Apparently Stan is having medical treatment for his back
- Ah, he is back, this report received May 15, 2022
People who attended the CHM were:
X Frank King 6.0
Stan Paddock
X Tom Szolyga 6.0
X Marc Verdiell 6.0
Tom was doing his thing and said he was making progress.
Mark got some parts rearranged looking for a wire clamp and when I left was getting ready to install the shaft.
Frank reproduced a big print deck a few times and got a punch check each time. Not sure why. Nothing accomplished.

Others are "filling in the blank"
from Marc
Likely present, Marc Verdiell, Frank King, Ken Shirriff, Tom Szolyga, others??

I put the shaft back in the machine [CT Tape], re-pinned the hub, and re-mounted the brushes (always a challenging operation, this last one). The tape drive should be good to test next week after I re-tension the main belts.

May 4, 2022
Apparently Stan is having medical treatment for his back
- Ah, he is back, this report received May 15, 2022
People who attended the CHM were:
X Frank King 6.0
Stan Paddock
X Tom Szolyga 6.0
X Ken Shirriff 6.0
X Marc Verdiell 6.0

The DE tape drives fail to write bits without hanging after a few seconds. The Disc light is on but I think it should be if it hangs

I had three groups of young adults about 12-14 years old that punched cards. Once they got the hang of it, they punched like pros. All that wanted a Big Print so I ran it for them. First group was about 10 -12, the second group about 20 - 25 the third group was 10 - 12.

The 1401 group had lunch together.

Tom sounded like he was making progress on his German project.

Mark found a lot of new things about the tape clutches and seems about ready to install the rebuilt braking system into the tape drive.

Ken and I worked on the CT # 3 729 that had the head down problem. It still will not dump tape in the right side when attempting to load.

Others are "filling in the blank"
from Marc
Likely present, Marc Verdiell, Frank King, Ken Shirriff, Tom Szolyga, others??

I rebuilt the CT tape brake clutch: pressed new bearings in, put new felt seals in (hopefully correct size and correct place this time), refilled with 29g of special magic iron powder, tested that it worked at the required current, then reassembled the main shaft with all 3 clutches.

I know that Tom continued to work on his serial interface over these last two weeks. He is making it quite user friendly by adding a nice color LCD screen.

Frank tested the machines and started working on the CT punch, which Jack Ghiselli had reported defective.

Ken worked on trying to figure out why the CT tape next to mine gets stuck in its state machine logic when trying to load a tape, and made some diagnostic progress. It is the only Model II tape with NOR logic that we have, which means we can’t compare its devilish load logic it with another working one, which is very annoying. Ken tried to explain it to me, and it sounded very complicated.

In addition, Google Gobble, the local wild turkey, was waiting for me at the side door when I went to get my lunch. He looked annoyed and suspicious, and let out a loud gobble. Incidentally, lunch was a turkey sandwich, so he had good reasons to be annoyed and suspicious.

May 7, 2022
from Jack Ghiselli
Steve Madsen and I did the 1401 demo today to 24 people. In addition to USA, we had visitors from Dubai, Delhi India, and Bratislava Slovakia.

We used the CT system for most of the demo, but since its tapes don't work we used the DE TAU and the one working DE tape drive. All three keypunches and the 083 sorter worked fine.

Still hoping for a working 1402 punch when the Restoration Team gets time.

Weekly 1401 demos on Wednesdays begin 5/11.

--Jack Ghiselli, Cell 408-839-1051

Apr 30, 2022 - demo
Jack Ghiselli and Pat Bruder
from Jack Ghiselli
Pat Buder and I gave the 1401 Demo on Saturday 4/30/2022. We had 28 visitors for the main demo and about 10 who wandered in later. In addition to the USA, we had visitors from Rio de Janeiro Brazil, Mexico City Mexico, and Warsaw Poland. We're trying to shorten the demo, and we got this one completed in under 45 minutes. Yay.

We used CT for the demo, except we demonstrated tapes on the one working tape drive on DE, which was fine. During demo prep, while using the TAU to space the tape forward, dummy me let it run off the end of the tape. Pat Buder was kind and did NOT laugh and take pictures of me clumsily performing the exercise of re-threading the tape back on to the feed reel. We had a card jam inside the CT 1402 Reader, but after we removed the brush assembly and cleared it the reader worked fine. All three keypunches and the 083 Sorter worked fine. The extra weight bar had come off one of the 1402 reader weights, so we cleaned off the goo and re-attached it with some new double-stick tape.

Our demo cart seems to be down to 5 SMS cards (there used to be 7) and 2 vials of cores (there used to be 3). That's still enough for the demo, but we'll try to keep track better.

We had a little extra time, so we took some Windows screen shots on the PC attached to the CT system, and I will fit these into the PCWriter operator's instructions I'm working on for Stan.q

Thanks again to the Restoration Team for all your hard work. When your busy time permits, we're still hoping for a correctly aligned 1402 Punch so we can replace up some of our bad demo decks.

We're hoping to add an additional weekly 1401 Demo on Wednesdays at 3:00, starting 5/11. We need to encourage some more 1401 demo volunteers to cover two a week.

--Jack Ghiselli, Cell 408-839-1051
from Pat Bruder
Last Saturday I was asked to do a special Revolution tour for a group of three blind visitors. It was one woman and two men, all in their late 20's. At least one of them had done some coding. As I often do, I tacked on a 1401 mini-demo at the end.

I did a similar demo several years ago, but that was for a single person and his attendant. Also, another docent did the tour and he and I did the demo. We both found it very rewarding.

Before this tour I did some research on leading tours for blind people and got some great tips.

Revolution Tour

The CHM staff gave me gloves for everyone so that we could touch selected items. Unfortunately Revolution isn't much of a hands-on experience, but I planned some places that they could touch.

One challenge was moving through some of our narrow, twisted pathways. They suggested we form a line with each person touching the one in front of them on the shoulder or arm. Sometimes they also used their blind canes to feel the way.

Because of the additional time it takes to describe everything I drastically reduced the number of stops we made.

IBM 1401 Demo

It turns out that there are many things to touch and hear in the 1401 lab:
   Key Punch
   1401 Cabinet and Panel
   Card reader
   Tape and tape drive
   Large cable
   Circuit cards

All of these were guided touching, and none were in motion or had anything exposed that would be dangerous.

All three of the guests can type, so keypunching was feasible. However, our vintage 026's don't have the raised dots on the "F" and "J" home keys found on modern keyboards. I had to help them position their hands, but they managed.

Lessons Learned / Opinions

Group size is important. One or two is best, and never more than three per docent.

It's best when the museum is closed, but we worked around the public.

Practice this special docent activity in advance. Carefully select each stop you will make. Think about how you will describe things for this audience.

Do research, especially seeking articles about museum tours written by blind people. An example of something I discovered before the tour is that you need not go out of your way to avoid terms that refer to seeing. These are prevalent in everyday conversation, and blind people are used to hearing them. Avoiding them is unnecessary.

Ask them if they want some particular assistance, and they will tell you how to help them if needed.


At the end of the day, they asked me to guide them to the entrance walkway by the parking lot so they could wait for the Uber they ordered. As before, I had a very pleasant and rewarding experience.


Apr 27, 2022
Stan Paddock and Marc Verdiell
from Stan Paddock,
Robert Garner 1.5
Frank King 6.0
Stan Paddock 6.0
Tom Szolyga 6.0
Ken Shirriff 6.0
Marc Verdiell 6.0
Allen Palmer 6.0

German System:
All three tape drives fail to work.
Allen and Frank checked the TAU,
Other than the tape system does not respond, no errors show on the TAU control panel.
(To be continued)

Connecticut System:

#1: the right brake clutch locks up.
Marc has pulled the brake unit.
Somebody, in the past, has worked on the brake and did not put it back correct.
A felt washer was left out allowing the break power to get into a bearing.
He says the felt seals are worn and he will replace them.

#2: Continuous errors for a few weeks.
Before bit 4 seemed to be bad.
Now I see problems with bits A, B, C. I.e. compare errors when writing from the TAU.
Frank and Ken measured the signals at the preamps and they looked fine.
Frank thinks it could be a cabling/termination problem since we've been moving cables around while working on other drives.
Ken and Frank still working on the problem.

#3: It still as problems loading, so Marc took the head assembly and fixed some broken parts. Frank put it back in and the heads move down and the tape starts to load, but the right reel doesn't work right and the load doesn't work.
Frank and Marc determined the head down switch is working as designed.
But the tape will still not load.

#4: The motors keep running and it doesn't load right.

We have a staffing problem so this problem has not been addressed.

Unit Card Equipment:

#2 keypunch ingested a punch card and it was difficult to recover.
Skilled unit record technician Frank King was able to fix the problem.

Stan Paddock
from Marc Verdiell

And big thanks to Allen that told me about the new felt seals that had been remade by Grant, how to remove the bearing by pressing it out, how to replace said unobtainium bearing with two obtainium ones, how many grams of magnetic powder to put back, etc, etc…

Apr 20, 2022 etc.
Stan Paddock, Jack Ghiselli, Marc Verdiell & Saturday Docent Report
from Stan Paddock,
Robert Garner 3.0
Frank King 6.0
Stan Paddock 6.0
Ken Shirriff 5.0
Tom Szolyga 6.0
Marc Verdiell 5.0

German System:
Did not address the whole German system on the belief that a week of rest may make it work better.

Connecticut System:

The Connecticut system has four tape drives: #1,#2,#3, and #4.
(Hi Stan, you wanted an update on the CT tape drives)

#1: the right brake clutch locks up.
Marc removed it.
He says the felt seals are worn and he will replace them.

#2: Continuous errors for a few weeks.
Before bit 4 seemed to be bad.
Now I see problems with bits A, B, C. I.e. compare errors when writing from the TAU.
Frank and I measured the signals at the preamps and they looked fine.
Frank thinks it could be a cabling/termination problem since we've been moving cables around while working on other drives.
I noticed bulb A was burnt out on the TAU panel, so I replaced it.

#3: It had problems loading, so Marc took the head assembly and fixed some broken parts. Frank put it back in and the heads move down and the tape starts to load, but the right reel doesn't work right and the load doesn't work.
The head load motor keeps running, so we suspect the head down micro switch isn't closing.
We suspect the mechanism that drives the head up and down is not synchronized when it was installed.
Next week.

#4: The motors keep running and it doesn't load right.
We are gaining experience on the tape drives but making progress every week.

Stan and Tom worked on the German to PC system.
The Connecticut to PC system communicated via the printer port on the PC.
The German to PC system will be communicating via USB.
The software in the PC in the German PC will be 70% of the Connecticut PC.

Stan Paddock
from Jack Ghiselli Fri 4/22/2022 11:40 AM

Re: Status of CT1402 Card Punch
I came in last Saturday to try again to punch an object deck from ROPE. Apparently, the CT 1402 Card Punch is punching cards out of alignment. Sometimes we blame this on poor quality blank card stock, so I tried several different types of blank cards, including old (probably good) stock pre-printed with various company information. Same problems.

Attachment #1

Attachment #2

Some of the mis-punching was really wild, and usually got 1402 Punch Checks. See Attachment 1. But most mis-punches were much more subtle and you had to use the punch alignment fixture to see the errors (see Attachment #2).

Interestingly, some of the mis-punched cards read OK sometimes on the 1402 reader, and sometimes not. Also, the 1402 reader seems much more forgiving of slight vertical errors than the 029 keypunch, which drops vertically misaligned zone punches when you try to duplicate a card. Probably this is because the 1402 reads cards from bottom to top on the long edge, while the 029 reads them side to side on the short edge.

Anyway, this mis-punching might be part of the cause of the flaky loading of demo decks we've recently punched. In the words of Native American actor Chief Dan George, "Sometimes the magic works and sometimes it doesn't."

Since the DE 1402 Punch is still down, card punching seems to be unreliable. If our overworked Restoration Team gets some free time, it would be great if you could look at this.

Incidentally, this does NOT affect the 1401 demo, since we don't use the 1402 Punch.

--Jack Ghiselli, Cell 408-839-1051
from Marc Verdiell Fri 4/22/2022 7:43 PM
Re: Status of CT1402 Card Punch

Good thing is, while working on the German punch, I got pretty good at doing the mechanical alignment. When I’m done with the 729 clutch I can realign the punch.

Saturday Docent Report, from Jack Ghiselli

Bill Worthington and I gave the 1401 demo today to 45 visitors. Foreign countries represented were Australia, France (Paris), and India.

We ran the demo on CT. Couldn't get any of the CT 729's to work with the TAU, so we used the DE TAU and 729's to demonstrate tapes.

CT tapes are still being worked on by Restoration.

1402 punches on DE is still down and the one on CT is misaligning.

026 Keypunch #2 is unusable. The program wheel is stuck oscillating and it won't feed or punch.

--Jack Ghiselli

Apr 13, 2022
from Stan Paddock and Marc Verdiell (and later from Frank King)
from Stan Paddock
Robert Garner 1.0
Frank King 5.0
Stan Paddock 5.0
Ken Shirriff 5.0
Tom Szolyga 5.0
Marc Verdiell 5.0

German System:
Determined the punch is still out of order.
We will have to determine when it will have to move it up on the priority list or it will not get repaired.

Also tested the tape drives.
Some worked some of the times.
Not available for usage for demos.

Connecticut System:

Marc continued his work on the first Connecticut tape drive.
He finished assembling the tape drive and tested it.
It started out running as design.
Then the right spindle started to jam even with the power off.
This is the same problem as before.
With all of the parts on the table in the workshop two weeks ago, we could not find any error and we resembled the spindle.
Next week we will remove the spindle and break in down again.
Then we will take the brake clutch and see what is wrong with it.
If we can not be sure what is causing the problem, we have a spare brake unit that we can install in place of the failed unit.

Frank noticed that the read/write head on the third tape was stuck in the down position.
Frank removed the belt that drives the head up and down.
With Frank, Marc and Ken working the problem, it was discovered that there was a slice of metal from the erase head that had followed on the read/write head.
This kept the head from going complete to the down position.
It was also noticed, there were two small screws that had broken off in the main block.
This was a further problem as both of them were broken off below the surface.

Marc has a well equipped shop at home.
He took the read/write head assembly home to see what he could do with it.
I will send along another e-mail from Marc specifying how he fixed the problems.

With luck, we might have both drives operational next week.

Stan Paddock
from Marc Verdiell

Subject: IBM 729 tape head repaired

I think the tape head is repaired. I extracted the two screws. I made a locating punch in the center of the screw stub, drilled a small hole in the middle, then used the screw extractor, both came (almost) right out.

The erase head plate did fit very snugly in its former footprint, so I just put fresh liquid cyanoacrylate and it locked back right in there. Also the erase head itself has a locating peg, so when I screwed it back on, it went right back to where it was. It should have retained the original alignment, which seems non critical anyhow, it’s pretty far from the tape. Ken believes it’s not used in our tape models anyhow.

I think we should be all good to go and can reuse this head if we wanted to. Plus it’s all cleaned up now.

Screws extracted:

Holes nice and clear

Erase head with the missing plate

Erase head with the plate back on:

Went back into the perfect place:

It’s all fixed (I think):

from Frank King in response to question by Jack Ghiselli

We ran programs from both systems. Everything worked with the exception of the tapes and the German punch. Only 1 of the tapes works on CT so, I would suggest for demoing the tapes, use the TAU panel. All 3 work on the German machine from the TAU using go forward and go backward.

Apr 9, 2022
from Jack Ghiselli
We demonstrated the CHM IBM 1401 on Saturday 4/19/2022 to 27 people, which was a more manageable size, and close to the size suggested by CHM staff. After the main demo, another 28 people came by and we gave mini-demos to them. I was Lead and Bill Worthington was Assistant. Our demo ran 50 minutes, which is a little long, and I'm working to shorten it up.

One of our visitors worked in 1957 with Honeywell on early magnetic tape drives. In addition to visitors from the USA, we had visitors from Germany and Italy, pushing our language skills.

The CT 1402 Card Reader/Punch was inoperative. There were cards left in the reader throat, the READER STOP light was on, and we were unable to perform a Non-Process Run-out on either the Reader or the Punch. So, we used DE. On DE, one 729 Tape Drive was marked as Out of Operation, so we used the right-most two drives. Using the Tape Exerciser (Ron 2.1) program, we were able to run the right-most tape, but the next to the left only did one write cycle and then stopped. So, we ran the demo using the TAU, and both drives worked OK. We didn't have time to diagnose the tape issue further. We ran BigPrint and Powers of Two for the demo, and both ran OK. All three 026 Keypunches and the 083 Sorter worked OK. Our sort deck is getting a little ratty, but with both 1402 Punch units down, we couldn't punch a new one. We found the Tape Exerciser (Ron 2.1) deck in the Demo Tray was missing its last 3 cards, so we duplicated new ones from another deck on the Keypunch.

Mar 30, 2022
from Stan Paddock
Attending were
X Robert Garner 1.0
X Frank King 5.0
X Stan Paddock 5.0
X Ken Shirriff 3.0
X Tom Szolyga 5.0
X Ed Thelen 3.0
X Marc Verdiell 5.0

German System:
(Paid no attention to this system today)

Photo Ops:
It has been a long time since we had seven 1401 people together at the CHM.
I thought it was time for some video evidence. Here

Connecticut System:

Marc continued his work on the first Connecticut tape drive.
Marc had rebuilt one of the brush block at home and installed it in the shop today.
He is now completing the installing the other parts.
The tape drive should be back on line in the next couple of weeks.

Frank notice the right take-up tape reel was not working right.

Using his many years of experience, he suspected is was a brush problem as we found on the first drive.
Frank adjusted the brush block and the problem went away.
Next week when all four of the Connecticut tape drives should be operational, we will check for errors on all drives.

The new keypunch ribbon being tested on keypunch #1 failed as we expected.
I am going to send them back.
I am going try and build a device that will re-ink our dry existing ribbons.

Docent demo cards:

On the disk of the pc that talks to the Connecticut system, Stan found a punch card file for BigPrint and powers of two.
Stan punched the two decks.
While these two decks are not the current revision, they both work fine.
They are on the punch joggle plate on the1402.

I expect to be able to be able to punch all of the current demo decks next week.


We had a visitor to the CHM last week.
His name is:
Daniel Van Dalsem
(669) 264-7553

Dan is a college student from Santa Barbra.
Depending on what he thought of our meeting last week,
he might join us during summer break.
His parents live in Santa Clara.

Tom spent the day working in the shop developing his PC to the German system.
This will be functionally the system we currently use on the Connecticut system.

Stan Paddock

Some relaxed pictures taken Wednesday, March 30, 2022
     - Music, stage play, and photos by Sandra Shu-Lee of CHM
     - Lyrics by Ed Thelen
Rap sheets of below suspects
     - "Is there anyone here that I haven't offended yet?"

The Line-Up. left to right, Robert Garner, Marc Verdiell, Tom Szolyga, Frank King, Stan Paddock, Ed Thelen, Ken Shirriff

Another angle

Ed with screw driver. "I might break something !!"

Ah, Ken will keep Ed out of trouble! a chaperone !

OK, somebody do something.

Frank at work. What more can I say??

This is Stan. Back on the farm, we would call him the "straw boss".

Guilty as charged !! Lined up for sentencing..
     - more pictures taken a few years ago

Mar 26, 2022
Demo Report and VOBJ Instructions, from Jack Ghiselli
We gave the 1401 demo today. I was Lead and Pat Buder was Assistant.

Excellent Handoff:       I want to compliment the Restoration Team for an excellent handoff after your work last Wednesday. Stan and whoever else was there (sorry, I don't know who) made brand-new crisp copies of BigPrint and Powers-Of-Two, on good-quality card stock. They also left a supply of good-quality blank cards in the CT 1402. They also left copies of single-card 80/80 list and 80/80 punch programs, plus a brand-new copy of "Server" which we needed to use for punching ROPE object decks. Everything was well labelled and placed right on top of the CT 1402. You guys rock!

Hardware Issues:       We used CT. It looked like DE would also have worked, but we wanted to punch some cards and DE's 1402 Punch is still INOP. Immediately after power-up, decks wouldn't load on the CT 1402 Reader. However, after a short 15-minute warmup, it worked perfectly. We had an initial problem getting the 1403 printer to work, until we noticed that the cover over the Carriage-Control Tape was open. We closed it and the 1403 worked perfectly. The 083 Sorter and all three 026 Keypunches worked fine. Again, many thanks to the Restoration Team.

Safety Issues:       It appears that the fire extinguisher is missing from the wall cabinet next to the A/V closet. Is this OK with CHM management?

Demo:       We had lots of visitors. We had 66 people for our main demo, plus 7 more who wandered in during the demo. This exceeds the COVID guidelines Poppy had given us, but we were too busy to guard the door. If we do limit attendance, we should consider running multiple demo sessions. We also had about 20 people who wandered in after the demo, so we gave snap mini-demos to them. We had visitors from Michigan and New York, and foreign visitors from Poland and South Korea. One visitor, Duane Sand, was an ex-Burroughs guy who was possibly interested in joining the CHM volunteers. I think he talked to Poppy also, so I hope she follows up. Due to poor planning on my part the demo ran a little long -- about 45 minutes, so I'll try to tighten it up in the future.

Follow-up on Bad Decks:       For the past several weeks, we've had problems with demo decks that won't run. Today we used the new Demo decks built by Restoration last Wednesday, and they go a long way to fixing the problem. To help further, I wrote a program VOBJ (Verify Object Decks), intended to help us in the future verify that our Demo object decks haven't been shuffled by poor card-handing. I developed it under ROPE, and brought a thumb drive of the object deck. Then we used the PC and Stan's "Server" program on the 1401, to punch VOBJ into cards on the CT 1402. Thanks, Stan, for excellent documentation. We put the VOBJ program deck in the Demo tray. We assumed the new BigPrint, Powers-Of-Two, Server, and 80/80 decks were intended for us, so we put them too into the Demo card tray. If they weren't intended for us, you can find them there. Operating instructions for VOBJ are attached and I'll work with Ed Thelen to get VOBJ put into his data base.
Data Base with instructions

Staffing:       Pat Buder and I have been doing the 1401 demos the past few weeks. However, both of us will be out of town next Saturday (4/2), and as of now nobody has signed up. Perhaps we won't have a 1401 demo next Saturday?

--Jack Ghiselli, Cell 408-839-1051

Mar 23, 2022
from Stan Paddock
Attending were
X Robert Garner 1.0
X Frank King 5.0
X Stan Paddock 5.0
X Ken Shirriff 3.0
X Tom Szolyga ??
Marc Verdiell 5.0

German System:
(Paid no attention to this system today)

Connecticut System:
While installing the brushes in the first tape, Marc noticed that one of the brushes was worn down to nothing.
In the past, Marc had built new brushes for the 729 tape drives.
Marc took the brush bracket home to install new brushes.
When Marc is able to come back to the CHM, he will complete the install of parts to the tape spool.

Frank powered up the number 2 tape drive.
A slight squeal had become anything but slight.
After searching for an hour, Frank found the source.
On the right reel shaft, there is a brake that was squealing.
What was interesting, not all of out tapes have this brake.
Frank checked the book as what to do to fix the problem.
Using his vast experience, Frank attacked the problem and the squeal is gone.

Frank said "I remember how to install new ribbons in a keypunch."
He installed the tape rather quickly.
He also removed the new ribbon and turned it over rather quickly.

We are running one of the new ribbon to insure it does not come apart like the last ones.
These are the same ones we ordered before.
We will try to find another way to make our old keypunch work again.

Docent demo cards:
On the disk of the pc that talks to the Connecticut system, Stan found a punch card file for BigPrint and powers of two.
Stan punched the two decks.
While these two decks are not the current revision, they both work fine.
They are on the punch joggle plate on the1402.

I expect to be able to be able to punch all of the current demo decks next week.

We had a visitor to the CHM today.
I have misplaced the punch card that I had him to write his full name and other ID.
So all I can tell you is his name is Daniel [Van Dalsem] and he is a college student from Santa Barbra.
Depending on what he thought of today, He might join us during summer break.
His parents live in Santa Clara.

Tom spent the day working in the shop developing his PC to the German system.
This will be functionally the system we currently use on the Connecticut system.

Stan Paddock

Mar 20, 2022, & 22nd
from Jack Ghiselli
I came in today (Sunday 3/20/2022) to investigate why some of our BigPrint decks are failing to run.

In the tray on the demo cart, we have three copies of BigPrint. I've labeled these "Good", "Bad #1", and "Bad #2". As you might guess from these clever names, the first one works and the other two fail, but with different symptoms. By comparing 80/80 lists of the object decks, I found the following problems.

  1. In BigPrint "Bad #1", card #0041 (object decks from ROPE have sequence numbers in columns 72-75) has several zone punches missing in columns 1-39. In particular, column 1 is supposed to have an "M", but due to the dropped zone it erroneously has a "4". This changes the "move" instruction (M) at memory location 1513 into a "punch" instruction (4). During execution, the deck successfully reads the date and first name card, but then hangs at this instruction waiting for the 1402 Card Punch to be made ready. If you did make the punch ready, the program would get into further trouble attempting to execute following damaged instructions. The fix for this deck would be to replace card #0041 with a correct card copied from the good BigPrint deck. I speculate that this problem occurred when originally punching the deck on the 1402 Punch or when re-punching a damaged card on the 029 Keypunch

    Recommendation: Whenever you use the keypunch to replace a damaged object-deck card, always hold the old and new cards together up to a light and verify that all holes got copied correctly.

  2. In BigPrint "Bad #2", cards #0041 and #0042 are missing from the deck. During execution, after reading the date and first name card, the program branches to the missing code and fails with a CPU Check Reset error light at Instruction Address 1525 and Op-Code of Blank (Invalid op-code). The fix would be to insert new cards #0041 and #0042 copied from the good BigPrint deck. I speculate that this error was introduced when a card load failed part way through, and the operator failed to do a Non Process Runout on the 1402 Reader and probably the two cards were left in the rollers and mistakenly discarded.
    Recommendation: Whenever a 1402 Card Reader load fails, be sure you use Non Process Runout to clear any cards remaining in the 1402. If you're unsure, check sequence numbers in object deck columns 72-75 to be sure you get the entire deck back together correctly.
  3. All three BigPrint decks in our demo tray are revision "BIGPRINT REV 16.8 GENERATED ON 03/18/2016". You can find this in columns 1-39 of Card #0007 and columns 1-2 of Card #0008. Unfortunately, this latest and greatest assembly listing has not yet been put into Ed Thelan's database of demo programs. Doing that would make chasing this type of problem easier.

    This investigation suggests that these particular BigPrint problems we've been having are NOT hardware problems. Instead they are probably card-handling mistakes that damaged the decks. However, we have seen some other errors. One example was sporadically we saw a BigPrint load fail part way through with a CPU Check Reset light. This might be related to hardware, or might be other deck errors that I haven't noticed.

    I have NOT FIXED these problems, because I've been investigating at home. I am scheduled as one of the Demo team for next Saturday 3/26, and will try to fix the decks then.

  4. All three BigPrint decks in our demo tray contain three copies of Card #0098. Due to the way the loading works, this does not cause any execution problems, other than reading two unnecessary cards. I speculate that when punching the original deck from which these copies were cloned, a 1402 Punch error occurred and restart procedures punched the duplicate cards. While not strictly necessary, the fix would be to remove the second and third copies of Card #0098.
Recommendation: If you are punching object decks on the 1402 Punch and a punch error occurs, be sure you check sequence numbers to verify that no output cards are lost or duplicated.

We demo folks seem to have deck problems fairly often. When I get time, I'll try to write a diagnostic program to check demo object decks for missing cards, and/or to compare a suspected deck to a known good copy. That might help.

--Jack Ghiselli, Cell 408-839-1051

Robert Garner says:
"Your perseverance in sorting out BigPrint deck faults deserves a raise! :) "
from Jack Ghiselli, March 22, 2022

I came in today (Tuesday 3/22/2022), and thought I'd try to repair our two bad BigPrint demo decks in the 1401 Demo Tray.

Progress: The problem with BigPrint "Bad #1" was that card sequence # 0041 was missing some zone punches in columns 1-20. I thought the fix would simply be to duplicate a replacement card from the good (working) BigPrint deck. Ah, that life were so simple. I took Card #0041 from the good BigPrint and duplicated it in the 026 keypunch. To my surprise, the duplicated card also dropped the zone punches. I tried slowing down the process by duplicating one column at a time, but still bad. Tried a different keypunch; still bad. I put Card #0041 from the "good" BigPrint deck on the card-hole-alignment jig, and the hole alignment looks bad, especially in the first few columns, which are the ones the keypunch can't duplicate correctly. Interestingly, the "good" BigPrint deck does load and run successfully (I tried it on CT), so apparently the 1402 Reader is more forgiving of bad hole alignment than are the 026 keypunches. Perhaps some of our other sporadic loading problems were cases when the 1402 was less forgiving? I considered hand-punching a replacement card from the 80/80 listing, but several other cards also looked poorly aligned. I speculate that when the original BigPrint deck was punched, the CT 1402 Punch was slightly out of alignment. Then later someone duplicated a damaged card in the deck, but failed to notice the missing zones in the duplicated card.

Status: We seem to have one "good" BigPrint deck that does load and run successfully (at least on CT). So, we probably can run the 1401 Demo this coming Saturday. We also have two "bad" BigPrint decks which might be difficult to repair, due to poor hole alignment on the "good" deck.

Recommendation: Perhaps on Wednesday (3/23), if the Restoration Team has time, they could get the latest and greatest BigPrint ROPE object deck on a thumb drive, punch a new "master" copy of BigPrint, and verify that the 1402 is punching correct alignment. The demo folks can make extra copies from the "master". I talked to Stan Paddock on Sunday, and as usual he was way ahead of me on this approach. Hooray for the Restoration Team, who actually know how to fix things.

--Jack Ghiselli, Cell 408-839-1051

Mar 16, 2022
People who attended the CHM were:
Frank King 6.0
Stan Paddock 6.0
Ken Shirriff 5.0
Tom Szolyga 5.0
Marc Verdiell 5.0

Warning: Stan says he is tired after these maintenance sessions
and has given me (Ed Thelen) permission to "edit" his reports.
This is chancy !!
I'm too tired to even show up for work :--((

German System:
We used the German system to try and isolate the problems we had with were having with program decks.

Connecticut System:
The last demonstration had a problem with the decks.
We had some of the same problems on both systems.
Ken was looking into the problem.
He noticed that with one BigPrint deck failed at 20% of the deck.
The second deck failed at 60% of the deck.
By taking the first 50% of the second deck and the last 50% of the first deck, BigPrint worked!
Way to go Ken.

In discussion, we determined the problem.
A couple of weeks ago, the docents helped making sure we had three copies of all of the demo programs. After testing a demo program, they made copies of the program on the Connecticut system.

We missed it this morning but the I/O check switch was off on both machines.
This will allow the system to read bad cards into memory.
Since there is bad data into memory, the system will crash when the bad section is hit by the processes.

Suspecting the problem, we checked cards punched by the Connecticut and found all of them were off registration.
Ed Thelen popping off:
Off registration as determined by what ??
We should have a "card gauge" - an aluminum plate with guide projections and 80 x 12 black rectangles indicating where possible holes should be.
If you can see aluminum in the card holes, you know which way, and how much, the holes are misaligned.
This is by far the best method of determining mis-registration ...

We were using the cards we paid to have made by a company who had never made punched cards before.
Comment from Robert Garner
Ah, so it sounds like the TimeCardsUSA stock may be slipping in the CT 1402 punch.
Bummer, but not surprising— we know that their card stock is a tad slippery.
(Last stock paper fab shut down 20 years ago now..)

I concur that our demo (and other program) decks should only be punched in our authentic/period IBM 5082 stock.
(Nevertheless, the TimeCardsUSA cards seem to work as date/name cards for BigPrint.)

- Robert

p.s. From our punched card info page:
"According to Tim, the last supplier of IBM and "US Gov't" spec card stock, which he called 100-lb tabulating index, was an International Paper mill in Louisiana, shutdown ~2008. He had supplied 20 - 40k punched cards at a shot to Bob Swartz of Cardamation, Pennsylvania, our last source of high quality/IBM-spec 5081 cards, whose business closed in 2009 after his death.

We have decided to take all of those cards and put them in the Audio room to be used for the IBM 001 punch.
Next week we will be punching all vintage cards for the docents.

Two weeks ago, Marc took the right hand spool and break assembly for the first drive of the Connecticut system. It was suspected that there was a bad bearing binding the shaft.
After Marc and Ken got the assembly all apart, they could not [ find? ] a bad bearing.
They oiled the bearings, today the re-assembled the whole shaft.
Marc was heard to say "After you have taken the whole shaft apart, it goes back together much faster.
He also said the 4 stove bolts and heavy tie wraps made it much [ easier? ] while installing the assembly.

While installing a brush block, Marc noticed one of the brushes was way too small. [ short? ]
Marc took the brushes home to install with brushes [ he ] had built in the past.
This short brush, more than likely, caused the bad performance on this drive.
Ed Thelen popping off:
Brushes just plain wear!! Are we doing "periodic maintenance"?
Then again, what is "periodic" in our usage ??

Tom Szolyga is continuing his work on his German machine to PC interface.

Stan Paddock

Mar 9, 2022 - removed -

Feb 16, 2022
From Stan Paddock - received March 13, 2022
Frank King 5.0
Stan Paddock 5.0
Ken Shirriff 5.0
Marc Verdiell 5.0
German System:
(Paid no attention to this system today)

Connecticut System:
Marc and Ken found two books that tells you how to take apart and put back all of the parts of an 729 IBM tape drive.
So they took out the shaft from the first tape drive.
The took the shaft with the clutches into the work shop.
In the shop, they took all the items off the shaft.
Now came the hard part.
When the shaft, the shaft behaved as if one of the bearings did not like turning.

With the bearings (3) on the table top, all bearings seem to turn with no problem.
I am sure when Marc and Ken get together, they will figure it out.

Frank said I remember how to install new ribbons in a keypunch.
He installed the tape rather quickly.
He also removed the new ribbon and turned it over rather quickly.

We are running one of the new ribbon to insure it does not come apart like the last ones.

Stan worked on the PC-029 transcription system.

Stan Paddock
from Ken Shirriff - tape drive
Update from last Wednesday's tape drive effort. The pin holding the front hub onto the shaft won't come out, so we're kind of stuck. Any advice from the experts?

Marc and Frank tried to drive the pin out with a hammer and punch, but it wouldn't budge. (This should be the easy part of the disassembly...) Apparently whoever put the pin in used a lot of force and it doesn't want to come out. We're considering penetrating oil or heating it. Drilling it out would probably be difficult because it's hardened. Any other ideas?

Here's a photo. The pin is behind the hub, indicated by the arrow.

from Allen Palmer - tape drive
THE PIN IS TAPERED it should have a slight inset on the small end. You may need to look very close to see which end it is. Some time in the past someone may have driven it in so hard as to extend the pin out on both ends.

I would not think of either heating or drilling it. Can you see the recessed end of the pin ?

from Grant Saviers - tape drive
If the ends of the pin are mashed, a light grinding might help sort the large end from the small end. If you need a replacement pin, I have many, but some caliper quality diameter dimensions will be needed at a defined separation.

Usually, pins are extra long. A trial fit determines the proper length and position, marked and then cut off with extra on the large end. A dremel cut off wheel is perfect for the job.

from Paul Laughton - 1401 Microphone Issues
Mic 1 volume is very low. The master volume control must be turned up high to make Mic 1 heard. As a consequence, the input volume control on Mic 2 must be turned down. This works; however, the demonstrator currently not speaking needs to mute their mic to avoid feedback.

I have observed that there is some cross channel activity between Mic 1 and the video. What I see is that when the video is playing but its output volume is turned off, the input level lights on Mic 1 mimic the input level lights for the video.

Note: I have also sent this message to Jon Plutte

from Ignacio Menendez
As last resort, take your high speed cutter rotary saw, and come in front to back on the aluminum hub… VERY CAREFULLY, and take it down to the point that all you have left is an UNDAMAGED reel shaft…
The pin should be then easy to remove by cutting it shorter, again with the cutter, and tapping it out. NOTE: all the area must be well protected with rags, to prevent the filings to get into the rest of the tape drive head, columns, capstans, etc.
AS LAST RESORT, I believe we have plenty of hubs, to sacrifice that one.

Feb 9, 2022 - from Stan Paddock and Ken Shirriff, with comment from Grant Saviers, and Allen Palmer and Ignacio Menendez
from Stan Paddock

Attending were:
     Frank King 5
     Stan Paddock 5
     Ken Shirriff 4
     Pat Buder 5

German System:

The German system was not powered today. It still needs adjustment of the punch unit.

Connecticut System:

Pat Buder is continuing on making sure we have three copies of the demo programs.

Stan worked on the stacks of cards in the Leibert room. Found in excess of 30,000 un-punched cards.

There are several boxes of cards to be put away next week.

Frank and Ken worked of the first tape drive. It appears that the brake in the right take up reel is putting on the brakes even with the power turned off. Work on this tape drive will continue next week.

Last week two of the Connecticut tape drives were flakey. This week, three of the Connecticut tape drives were flakey.

Liebert Room:

In the Liebert room there is an PC tied to an 029 keypunch. This has worked to punch cards from files on the PC for 10 years.. It broke down several months ago.

Frank showed me a simpler way to connect the units together. Today, I made the final connection between the PC and the 029. Next week we may have the system up and running again.

Stan Paddock

from Ken Shirriff

Frank and I took a look at tape drive 1 on the CT machine today, with some help from Stan and Pat. It's failing to load the tape; the mechanisms move but the tape doesn't go down into the right column.

After some investigation, we found that the right reel was kind of stuck. With the release button held, it would move only a bit, rather than rotating freely. I turned off the power and it was still stuck, so it's not an electrical issue. Frank and I investigated more and it started rotating a bit, and then rotating more, and then eventually rotating freely. We hoped that it was fixed, but when we tried the tape drive again, the reel immediately wedged up again.

Our conclusion is that the brake clutch is at fault. Each shaft has three clutches: one to rotate forward, one for backward. , and one to stop motion. The forward and backward clutches work fine, but the brake clutch seems to be getting stuck. The clutches are magnetic, with iron/graphite powder that binds the clutch plates when the coil is energized. So it's unclear what would cause the clutch to stay engaged with no power applied. Maybe Iggy has some ideas?
Frank and I considered removing the clutch to examine it, but it is a complex process (see below) and we didn't have time today. This would be a good job for someone with more mechanical skills than me, e.g. Marc.


One thing I forgot to mention. Frank noticed a lot of debris on the bottom of tape drive #1. This appeared to be magnetic tape shredded into 1/16" bits; there was one larger fragment about 1/16" by 1/2" that was clearly tape. It's hard to figure out how this would get created. At first we were concerned that it was bits of metal or clutch powder, but that doesn't seem to be the case. I vacuumed it up.

Comment from Grant Saviers

The iron powder in the clutch has a proprietary additive (it's not graphite) that keeps the iron powder from sticking together. We sourced the replacement powder from a company in VT or NH, I'd have to search a bit to find the reference. If moisture got in or if it wore out then then replacing the powder might be the solution. Look at my report for the amount.

The other causes could be a failed original bearing (not available) or the make do replacement ball bearing pair that I found adequate for the application. Then there are the wool felt seals that hold the powder in the clutches, these do wear out. I made the punch to make these and left it for the shop when I moved.


from Allen Palmer (a day later)

Just some thoughts

Loss of powder would not cause the problem, just the opposite - the cultch would turn freely on the shaft but fail to engage to the shaft. Hard to picture the ‘powder’ getting so solid as the design of the internals are made to break up the powder.

From the symptoms you list I would suspect are physical like grant listed, most likely the bearing or the shaft has ‘rusted’ tight inside the reel.

You will need to pull the whole clutch assembly out. If it is the break clutch 9 if memory serves me still) you can pull off the break reel by itself and check it.

There are some ’tricks’ to supporting the rear bar & the pins that align it. Also replacing the brush pads can be a ‘pain’ getting them on & adjusted. Just takes time & patiences. Be very careful about hammering on the end of the shaft - you do not want to do any ‘mushrooming’ to the shaft.


comment from Ignacio Menendez

Just to complement Allens comments, there are 4 long ‘stove bolts, that you insert in place of the 4 bolts securing the rear heavy casting, and as you are pulling the rear casting back, don’t forget to hold the shafts up (I use old coat hanger wire), to keep the weight of all the components from bending the shafts.
Just my $0.02 worth.
P.S. these 4 stove bolts are inside one of the two large red tool boxes, in one of the drawers.

Feb 2, 2022 - from Stan Paddock
Attending were:
Frank King - 5.5
Stan Paddock - 5.5
Pat Buder -5.5

German System:
We powered up the German machine today because it was 50 degrees when we came in today

Connecticut System:

Pat Buder took over the work on making sure we have three copies of the demo programs.

Stan worked on the stacks of cards in the Leibert room.
Found in excess of 30,000 un-punched cards.

I think there are several boxes of cards to be put away next week.

Frank has worked on the IBM 083 sorter.
It is still a little flaky.

Last week two of the Connecticut tape drives were flakey.
This week, three of the Connecticut tape drives were flakey.

Stan Paddock

Jan 26, 2022 from Stan Paddock
Attending were:
Frank King - 5.5
Stan Paddock - 7.5

German System:
Did not power it up today.

Connecticut System:
We brought out a new ribbon to the printer and installed it.

Stan Worked on the demo programs.
The demo team was in and Pat Butler asked for three copies of each be made.

One copy for a master deck accessed by the hardware team.
One copy for the docents to use their master during demonstrations
One copy for the docents to use as a backup of their master deck.

Next week, the plans are to punch all the demo programs (primary and back up copies.)

We could use some help from people who can read IBM 729 technical books.
Is not a complicated as Apollo devices but still fun to work with.

Stan Paddock

Jan 19, 2022 from Stan Paddock
Attending were:
Frank King - 7.5
Stan Paddock - 7.5

German System:
Tried to test the tape drives.
Tried the tape test software.
Did not work.
Tried to test the drives with the TAU and all three drives will not respond.
We marked the tapes as down and went to lunch.

After lunch, we thought we would give it another try.
Frank re-loaded the tape test program and all three tapes came to life..

Connecticut System:
Frank used the tape test on all four tape drives.
The first tape has a problem that needs to be addressed.
The second has a prolay stutter that needs to be addressed.
The third and fourth drives seem to be fine.
We brought out a new ribbon to the printer.
We will replace it next week.
The knob the select the number of lines per inch needs to be tighten.
This will be fixed next week.

Stan found several copies of demonstration programs for the docents to use.
Next week, the plans are to punch all the demo programs (primary and back up copies.)

We could use some help from people who can read IBM 729 technical books.
Is not a complicated as Apollo devices but still fun to work with.

George Ahearn's son-in-law Alex stopped by today.
He dropped off a box of blank cards, some pictures of a 1401 work shop and a computer book.
Stan Paddock

Jan 12, 2022 from Stan Paddock
Attending were:
Stan Paddock

I knew Frank and Tom were not coming in today but I did not know if anybody else would be coming in.
Nobody else came in.

Following our safety rules, The only machine I turned on was a PC.

Last week I got the old PC <> 1401 operational.
I can punch cards from the PC!!

I am now assembling all of the demo programs and will punch two decks each.
One deck will given to the docents to use for demos and the other deck will be stored away as master.
If one of the docent decks fails, the docents will let one of 1401 team know and we will punch a new docent deck for them.

In searching for something in the Leibert room, I found we have at least two years NOS blank punch cards in there.

German Printer:
Last week Frank King, loaded the German printer with a lot of hydraulic oil.
I placed three Pig Blankets under the hydraulic of the printer.
I checked for oil leakage today. None!

It must only when the printer is running.

Jan 5, 2021 from Stan Paddock
Attending were:
Frank King - 7.5 hr.
Stan Paddock - 7 hr.

German System
We have known that the IBM 1403 printer was leaking oil. We have noticed that the leaking has stopped.
(The lack of an oil leak is because the oil level had dropped below where it leak spot)
Frank brought out the big can of oil and filled the reservoir.

Connecticut System:
Frank checked the oil level in the IBM 1403 printer and found the oil level is correct. Frank started going through the demo programs for both systems.
We found two copies of BigPrint.
One works fine and the other does not.

Connecticut to PC connection:
Stan re-assembled the cable from the PC to 1401 Serial Port, and attached them together.
Since it has been so long since the PC was used, it forgot the date and time.
Had to run a Setup program to reset all of the BIOS parameters.

Demo Card Decks:
Stan found an old control program copy for the 1401.
Stan loaded both programs into the PC and 1401 and ran some tests.
The ability to punch cards works fine.

Next week, the plans are to punch all the demo programs (primary and back up copies.)
Ed Thelen here, we should draw a diagonal line on the tops of all card decks,
to help identify when a deck not complete or shuffled.
I also used to label the first and last card to help assure a complete deck.
IBM 083 Card Sorter:
The sorter showed an capability to jam the cards and put the cards in the wrong cards in the wrong bit. Frank talked to the sorter every time it failed.
Frank made adjusted every time it failed.
When we left the CHM today. the sorted had learned its lessons.

Stan Paddock

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