Schedule March 2008

Wed March 05 - general,

Thu March 06 - Tape Team

Wed March 12 - general

Wed March 19 - general

• Present were Ron Williams, Bob Erickson, Frank King, Glenn Lea, Dan McInnis, Bob Feretich, Joe Preston, Judith Haemmerle, Stan Paddock, Robert Garner, and Ed Thelen.

• Glenn and Stan are busy replacing a repaired circuit breaker. And we tell our kids (and anyone who will listen) that computers are a hands clean, white collar, sit at a desk business :-|

• from Bob Feretich
  

  The below scenario now works reliably... Define virtual drive 1 and map it to a tape image of the program to be loaded and executed. This file is generated from the Autocoder cross-assembler (currently some manual editing is required)  in "loadable tape" format and converted to SIMH format. Define virtual drive 4 and map it to the tape image of the data file to be printed. This is a pure ASCII text file that is also converted to SIMH format. Load and execute the program from drive 1 by pressing the "TAPE LOAD" button on the 1401 console.  The program can read or write as desired to the data tape. We needed to replace the "Tape Load" switch today. It was noisy and would generate multiple tape load initiation pulses. Also today, Van has released a new version of the Autocoder cross-assembler that will interface with the Emulator. It needs to be integrated  into Rope. This integration would permit us to perform more comprehensive stress testing. Regards, Bob Feretich

• Ron Williams has been pestering Frank King about a defective diagnostic lamp in the 1403 printer - so Frank went after it. We found the lamps sent to us by J Falk and went to work.

• About 3:30, a docent brought in a group of computer science students from Aalborg University, Denmark. Their badges indicated that they had also visited Google. We gave them the BIG PRINT demo using their names. Stan and Bob also gave lectures ;-))

• Ron Williams traced an intermittent squeak to a fan in the 1401. Unfortunately for Ed, Ron assigned the repair to Ed Thelen. After hours, with power off, Tim Coslet and Ed removed the fan, leaving the wires connected. Placing oil on the C-Clip did not do the trick. Stan Paddock came back, and joined the effort. We had to get the C-Clip off to get the motor apart to correctly oil the bearing shaft. Getting that little C-Clip, recessed in the motor, off was a challenge.
  Ed (the German) and Stan (the Welchman) argued who was more stubborn. Dan McInnis (the Irishman) came by and claimed to be the most stubborn. Stan evidently won as he finally got the c-clip off. Stan greased the bearing shaft claiming the job should last another 50 years.
  Possibly Stan should have used lighter oil as the fan run-down time is still quite short.

Sat March 22

• from Stan Paddock - Monday Dry Run - for Docent Demos of 1401 -

  I worked with Ron Williams today on the 1401. It will not stay powered up for more than 10-30 seconds. In that case, I don't think I can help on Monday and will find something else to do. Stan Ron Williams made a liar out of me again. After I left, he found a bad card in the power supply monitoring. Ron 'found' another card and the machine is back up. We have been looking for this problem for several months now. Way to go Ron. See you on Monday. Stan

Mon March 24 - demo group,

To keep you up todate, the demo group, Bill, Stan, David, Jim and myself met this morning to do a run through of my latest BigPrint/Tape program and discuss integrating it into Davids script.

Things didn't go so well. We were unable to get the program to complete its assigned tasks. The reader had problems with the original deck, we punched out a new one and this ran ok, the printer gave print checks which we did not understand. Never got around to testing the tape portion. The punch also was getting validity errors. Stan is going to run it on Wednesday while the experts are on hand.

I am attaching a rough draft user's guide. The program run fine on SIMH and I have tested all the various combinations.

Dan

Wed March 26 - general

• Present were Ron Williams, Frank King, Bill Flora, Glenn Lea, Bob Feretich, Joe Preston, Stan Paddock, Robert Garner, and Ed Thelen.

• E-mails of problems last Saturday and Monday (above) had circulated, and all the section leaders of the reported problems were present. Jim Somers came by to assure that we were working toward getting the hardware back up to demonstration requirements. So many things all at once.
  Looking back - what is the common element? Power supplies! But that is hind sight :-((

  Ron Williams found a warmed card, driving power sequencing relay #2, which if replaced, helped keep the power up. Unfortunately, the drive voltage to relay #2 still was pulsing, not the steady level it should be - Tracing back the inputs, -12 volts looked like this. The scope indicates the -12 volt power supply is outputting -11 volts with a saw tooth output of +- 1 volt at the power frequency, 50 HZ, 20 ms for a complete wave :-(( This is sick !! So Frank King, whose printer had been reported as getting sync checks, wanted to clear that fault, and his good name!! He is removing the -12 volt power supply to fix it. He replaced a couple of suspect pass transistors (2 of the seven BIG ones). But the bad ripple and undervoltage remained :-(( Now what??? Lets look into that 50 Hz ripple, it should be double the power frequency because of the full wave rectifier circuit (two recifiers) - maybe one rectifier is open and causing problems - although the problem should not be a ripple looking like this because of the regulator actions, but lets look anyway. Both diodes tested good with an ohmmeter, and the transformer winding seemed good also -- Frank had to leave - but we all agreed there was a power problem, not a printer problem !! ;-))

• Now what? So Ron Williams and I started fooling with another similar power supply - Here is the setup to verify that big electrolytic filter capacitors are properly formed -

  Ron Williams remembered that a - 6 volt power supply is used as a reference, until the -6 volts is present, the -12 volt power supply only produces -6 volts (I imagine to help protect the transistors in case of a -6 volt power supply fault.)

  I am 50% convinced that there is a -6 volt reference problem - causing the -12 volt power supply to produce such trash :-(( It was about 5:00 and we were slowing down - and left -

• Another (unreported) problem during the demo exercizes was the 729 tape drive window did not stay all the way up. For several years it has sagged about 1 inch down and the work around was to cheat the interlock - which the docents did not know how to do - probably just as well :-|
  So they held the window closed with a big wood working clamp - and struggled on with other problems.

  Glenn Lea and Bill Flora worked on that problem - They eventually removed the shock absorber type spring assemblies which holds up the window, applied WD-40?, and gave the spring assemblies some exercize. For reasons not understood, the assemblies now work fine, the window behaves properly (does not sag down), and docents don't have to know how to cheat the window interlock :-))

• E-mail from Stan Paddock to Bob Lange, CC Gary Matsushita, Dennis Cassar

  Bob, Today, we took all of the covers off, disconnected the interconnecting cables, removed the roller stoppers and removed the interconnecting cable tray on top. The left most cabinet has all of the batteries. There are two roll-out drawers. We might be able to roll them all the way to your truck! The second cabinet also has rollers. The inverters in this cabinet unplug so if we need to reduce the weight, we can pull them out. The third cabinet is empty. If you bring a couple of strong people, you could be in and out in an hour. We have pallet jacks and an electric 2,000 pound fork lift available for your use. ...

  Views of the Uninterruptable Power Supply (UPS) in process of dis-assembly for removal.

• Robert Garner wishes to remind CHM folks that the big Liebert air conditioner near the door needs to be removed by the end of April, when the "new" ;-)) 1401 is expected to arrive at CHM.

Thu March 27 - Tape Team