Schedule June 2008

Wed June 4 - General

• This report is from Judith Haemmerle and Ron Williams, Ed Thelen was AWOL ;-))
  Present were Ron Williams, Bill Flora, Frank King, Joe Preston, Stan Paddock, ...

• Bob Feretich reinstalled the -20 V supply

  and removed the 3 volt marginal supply. (1402)

• Bill Flora is looking into the 7 CBs in the reader end of the machine that were apparently updated to photo disk CBs.

• Bill, Ron and Judith made archival photocopies or the 31 and 32 pages of the CPU and the 1402 wiring diagrams.

• Stan is working on the new text for the Big Print program per Robert Garner and fixed the jamming problem in Keypunch #4.

• Frank continued work on the 1403.

• All the 1401-2-6 air filters were vacuumed.

• Joe continued working on the recalcitrant 026.

• I [Judith Haemmerle] was photocopying most of the time, so I didn't really get any pictures. I took a couple after most folks had gone home. Here's one of Frank and the printer that I took last week, and one that shows the workspace - you can always tell serious work is going on when the jar of "red jam" comes out. ;) I'll send a second email with some of the places Bob F. worked on.

• Stan sent pictures of work to be done on the CT 729s
  

• Robert Garner suggests - thinking of organizing our bios into 3 pages, one each for:
  1. Active/core restoration team (incl remote folks like Van).
  2. Original 1401 design team members/1401 owners
     (including Buzz, Scott, Arnold, Rolf, Van, Macklin, Fran, and Shel.)
  3. Emeritus - folks who have worked on the restoration project, but are no longer active.

• From Lyle Bickley, of the PDP-1 team - Thursday -
  

  Steve [Russell] and I checked out the scopes in the 1401 room(s) today. We did a cursory checkout of the (4) channel TEK 2465 - and all the major functions we tested worked O.K. We will use it for debugging the PDP-1. We moved it to the PDP-1 demo room. We also "confiscated" the TEK 535 that was stored under the desk in the 1401 room. We will use it as an illustrative "period" piece of test gear. Another member of the Team volunteered to donate a "period" cart for the 535. Thanks to Len for obtaining the TEK 2465 from SLAC and the 1401 Team for the TEK 535!!! Cheers, Lyle

Wed June 11 - general

• Present were: Ron Williams, Bill Flora, Bob Feretich, Joe Preston, Stan Paddock, Judith Haemmerle, Robert Garner and Ed Thelen.

• Bill Flora and Stan Paddock were busy laying power and signal cables for the CT (Heck, I can't spell it) 1401. Just look at those heavy things - and be happy with the USB cables connecting your modern PC ;-))

• Ed Thelen continued testing CT 1401 power supplies. These are the power supplies for a machine thousands of times less powerful than your modern cell phone.

  One power supply had a screw with a broken off head. May have caused interesting troubles. Ron and Stan dug it out :-))

• Ed found a power supply that seemed to short at almost no load - but was OK into a 10 megohm load - Here is Bob Feretich struggling with the odd thing. Turns out the effect was marginal and intermittent - see next Wednesday -

• Ron Williams and Judith Judith Haemmerle struggled to find valid BIGPRINT decks -

Wed June 18 - General

• Present were: Ron Williams, Bob Erickson, Bill Flora, Frank King, Joe Preston, Judith Haemmerle, Robert Garner and Ed Thelen.

• Just one of those days - almost nobody in top form - except possibly Joe Preston - who delightedly reported that the # 3 keypunch print mechanism is FINALLY adjusted correctly - We now have TWO "experts": (1) Bob Erickson who reluctantly did one for us in 2006, and (2) Joe who finished one today. Bob Erickson reported that frequently a whole region of IBM would have only one expert of the 026 print mechanisms.

• Here are symptoms of our unreadiness to work - Bob Erickson wanted a picture of this backside of a regular coke can

  And Ron Williams wants to have this ALD (Automated Logic Diagram) blown up to wall size as a display

  And do Ron Williams and Bill Flora look organized?

• Well, OK, Frank King was in top form, introducing the 1401 systems to his daughter Carla, who is usually motorcycling in Russia, China, Greece, ... Carla brought: "Lyn Bishop - she's a very well known digital artist who combines digital and fine art. She heads up an annual project at SIGGRAF and gets the latest equipment like large-format printers from Epson, etc. lynbishop.com [and] Kip Inscore, Peter LaPierre, Jim Inscore."

• Then we had lots of visitors, and Frank worked his charm on them also ;-)). Ron Williams operated the machinery, the mag tape chattering like a machine gun and the printer pounding out BIGPRINT with visitor's names ...

• Frank had mentioned that the drive chain motors in the German and Connecticut 1403 printers were completely different - The German (at 50 Hz) had the outside rotating - lots of inertia The American (at 60 Hz) was the usual form, the inside rotating Here is Ed Thelen reading up on "Synchronous Hysterisis Motors" at his "workstation", complete with microscope, radio to listen to 1401 electrical noise, and 40 watt vacuum tube audio amplifier.

• Ron Williams (tongue in cheek???) is suggesting that we appoint a committee to nominate an action committee to look into making another debug podium and book case, such as used on the German 1401 (see picture) especially for debugging the Konnektuct (is that really how you spell it?) 1401.

• Judith Haemmerle helped Ed (all thumbs) Thelen remove the last two power supplies from the CT 1401. Another brass screw head broke off while untightening the wire lugs. Judith labeled the wires using tape and permanent marking pen. The second -12 volt 20 amp supply tested fine.
  The second -6 volt 12 amp power supply had the same symptoms as the first -6 volt 12 amp power supply. (The extra power supplies come with the two box 1401 which is the size we all know and love.)

• The two -6 volt 12 amp power supplies acted as though they were "crowbaring" - placing a thyristor across the output causing a short circuit, forcing the circuit breaker to open - often used to prevent an over-voltage from damaging computer circuitry. To keep things from getting exciting, I placed a 60 incandescent lamp in series with the power supply - this also helps form any capacitors that un-formed during non-use.
  BUT there was no "Crowbar" card as in the German 1401 !!

• After much casting about for power supply diagrams - Judith mentioned that there were moldy diagrams in a box in invisible storage - waiting for an excuse to get photocopied to archival paper, and then to working paper.
  Off we trotted, found the moldy mess (actually not quite that bad, you could separate the pages) and made archival and working copies of the power-up sequencing and power supplies. :-)))

• Here is the schematic of the power supply, conservative design for 1958. The incoming 133 volts is from a ferroresonant regulator, the rectified voltage on the three main filter capacitors is 12 volts - lots of "head room" for the linear pass transistors to output a regulated 6 volts. The red boxed areas, "detailed" below, refer to an "OverVoltage Receptacle" - which did not seem to be present!

• Mostly out of desperation, I "borrowed" a bank of adjustable load resistors from the PDP-1 group - no body was there to object ;-)) and set it for 1.4 ohms which was about 1/3 rated load. I connected it to the - 6 volt power supply - and it worked just fine. We had forgotten that pass transistors leak some, and at no-load, there was not enough resistance to drain the leakage, and over voltage occurred tripping the over-voltage circuit and thyristor - which we did not find !!

• Searching more seriously for some overvoltage and crowbar circuit, I noticed this little assembly buried in the power supply - it MUST be the optional crowbar circuit !!

• All of the major power supplies have tested OK, and have been re-installed in the CT-1401. - it is ready for the smoke test, - lets reword that - ready to try to power up :-|
  Oh yes, the electrician was in the 1401 room today, studying the three phase 60 amp connectors and electrical service box.
  We ought to have power available to the CT-1401 system "Real Soon Now" :-)))

• Here are the major power supplies in a "normal" 2 box 1401

  1) + 6 volt, 8 amp 2) (hidden) Ferroresonant transformer & capacitors 3) + 30 volt, 7 amp 4) -6 volt, 12 amp

  5) + 6 volt, 16 amp 6) -12 volt, 20 amp 7) -6 volt, 12 amp 8) -12 volt, 20 amp

  The 5 vertical telephone jacks between 4) and 5) are for voltage "margining" to help weakening parts fail to function properly during testing, rather than in service.
  And below identify some "minor" power components and supplies. Will have to ask Ron to help identify -

  a) power sequencing relays b) two power detection cards c) - d) -

  e) - f) - g) - v) variac

• Judith says that we, the 1401 group, are invited to lunch and mini-tour at Google. They need a head count and three weeks warning. A proposed date is Wednesday June 9th - any takers ?? I plan to eat for two ;-))

Wed June 25 - All hands meeting, general