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Activity Report - August 04, 2004 by Ed Thelen

Subject: Wednesday's gathering

Ron Williams, Allen Palmer, Bob Erickson, Donald Cull, LaFarr Stuart and Ed Thelen gathered today for another joust with dust, fans, electronics, and each other. Mary and Dag made the scene briefly.

Ron Williams presented his capacitor exerciser box which was really slick.
Ron Williams'

capacitor exerciser box
The label says

Selectable incandescent primary limiting
electrolytic capacitor resuscitation engine
Power Supply
- blaming Ed in case of trouble. :-((

The schematic is under the above label.
The photographer who did not remove the two alligator clips from the top of the box has been chastised!!!

Ed Thelen brought a variable voltage 0-130 V AC, 0-180 V DC that - well - looked like home built. (The 729 tape drives have 140 volt power supplies.) Note that Ed Thelen is not shown standing behind his product, poor Don Cull got stuck with that job. :-((
home built

All of the 1401, 1402 and 1406 power supplies have had their electrolytic capacitors checked under full rated voltage and appear fully functional with rated capacity. Five of the eight removable power supplies deliver rated voltage, the other three removable power supplies appear to depend upon control inputs to regulate correctly. These power supplies have not been tested under rated load - and that exercise might not be worth the trouble and risk (I regard handling and exercising artifacts and electronic equipment as having some risk).

Don Cull and Ed Thelen also checked the electrolytic capacitors of the several non-removable power supplies in the 1402 (including the 1403 hammer driver power supply with 24 big capacitors).

Up to this point, there have been *NO* observed capacitor electrical failures nor need for re-forming. (All capacitors withstood rated voltage with no observed current absorption for reforming.) I e-mailed Arnold Schweinsberg asking if he had changed the capacitors that had leaked electrolyte (see discussion and pictures) and he implied that he had not changed them. He said that the 1401, 1402, 1403 and 1406 had not seen voltage for 16 years.

We forgot to ask, and have not heard from the IBM 1620 Restoration Group or the PDP-1 Restoration Group about their experience with electrolytic capacitors. Their machines were from the same era. The PDP-11 was reputed to have been demonstrated working in 1992 - 12 years ago.

Ron Williams and Bob Erickson worked on 1401 and 1406 fans and general dusting and cleaning.

LaFarr Stuart and Allen Palmer alligator wrestled the 729 tape units.

Green 729 power supplies
Allen Palmer and Ed Thelen are studying checking out the power supplies for the five 729 tape drives. Would you believe that each the 729s have the following power supplies -48, -7.5, -6, +6, +12, +73, +140 ? Yup, they do indeed!! Most of these are generated in one large (15 inch x 3 foot) open box. ? remove it to bench check? check in place laying on the floor? - which is the least error prone? Arnold says the 729s have not been energized for 20 years - say 1984.

There is now a phone in the 1401 room 650 818 1037. By next Wednesday the system should be able to ring it. This can also help with the access problem. If you are at the administrative entrance, you should be able to dial this number and wake someone up.

This schedule of meeting Wednesdays at 10AM is expected to continue.

Ed Thelen tied a little push-to-talk radio phone to the entrance nearest the 1401 room to help let folks into the building. It worked well, and didn't even get stolen :-)) I will do that again this coming Wednesday August 11th.

Arnold Schweinsberg via Rolf - RolfCom - August 1 2004
Hello Ed,

The 1401, 1402, 1403 and 1406 have been connected to power supply 15 to 16 years ago,
The 729 tape units have been switched to power about 20 years ago.

The parts should recover themselves when in service.
The AC - part on DC-Voltage should be checked, in German it is called "BRUMMSPANNUNG". I (Ed Thelen) presume that could be called "ripple". "Ripple" could be "excessive" if the capacitors are too small (not enough capacitance) for rated load. During capacitor checking, we have been verifying that the capacitors have their rated capacitance.

For the 5 capacitators 10.000 ufd my dad is sure that they have been produced a long time before 1992. May be 1992 is the exipiry date/best befor date of these elements.

Have you connected the whole system to a 50 cycle-converter yet?

Greetings from Arnold an Rolf

Action Pictures:

First - Olympic Floor Exercises

1402 Floor Exercise

Don Cull performing

1406 Floor Exercise

Don Williams performing

1406 Floor Exercise

Don Williams tagging power supply

729 Floor Exercise

Allen Palmer performing
Second - Customers don't see these much

1401 C. E. Panel

1401 Tape Adaptor Panel

Williams House Keeping Fan

Something Missing

from the 1402, a mystery :-))