Schedule Febuary 2006

Present were Ron Williams, Bob Erickson, Allen Palmer, Bob Feretich, Chuck Kantmann, Robert Garner, Jeff Stutzman, Ed Thelen. Bob Feretich's brother Jim, visiting from Chicago, helped from about noon to 6:30 P.M.

• Allen Palmer worked to get all the indicator lamps on the 729 Mod 5 tape drive working correctly and gave demos of the drive passing tape in the forward direction and rewinding :-))

• Allen Palmer dug out this off-line tape tester. We hope that this text translated from German is a close relative.

• Bob Feretich and his visiting brother Jim opened it up and are attempting a reverse engineering. This involves tracing and documenting all the wiring, switches, and the three circuit boards in the unit. This is turning into a non-trivial job as we don't have the schematics for the three SMS cards in the off-line tester.

• Bob Feretich (and the rest of us) have a problem identifying some resistor looking parts - there are too many color bands. Here is a chart of what he sees. Anyone identify what are the components or what are the values please e-mail Ed Thelen.

• Bob Erickson, Juff Stutzman and Ed Thelen worked on the 077 collators. They swapped out the bad feed rollers and the electric motor from the German machine into the Visible Storage machine. The two motors had different shaft sizes and there is no bushing for the oiler pulley to drive the oiler pump on the Visible Storage machine. (There was no oiler pump on the German machine which used needle bearing and likely needed more frequent oiling.) Possibly the lack of oil caused the failure of the needle bearings. The Visible Storage machine used porous bronze bearings instead of the needle bearings. "We" determined that the makeshift 48 volt power supply in the German machine (with the disabled circuit breaker) is likely more robust than the selenium rectifier based power supply in the Visible Storage machine and are not swapping them. We are almost ready to return the Visible Storage machine.

• Some images from past work sessions -

  Ed Frank 1403 First Printing

  Bob Grant 729 Connector

  Bill Bob Frank Ron Ed 1403

  Bill 1402 Read Timer

  Grant 729 Working

Added to Jan 14th log to add detail and credit -
To replace the defective printer column 131 hammer solonoid, Ron used our only spare solenoid coil from his CE friend Phil Clark (Thanks Phil!).

Present were: Ron Williams, Bob Erickson, Frank King, Chuck Kantman, Don Cull, Glen Lea, Grant Saviers, Bob Feretich, Bill Flora, Ron Crane, Jeff Stutzman, Robert Garner and Ed Thelen.

• We had an honored guest, Dave Hawley - right, President of the Australian Computer Museum Society. Dave was toured about the Computer History Museum and its Visible Storage by Robert Garner.

• The 1403 printer is working well, so Frank King put the exterior covers/sound barrier back on. Chuch Kantman and Glen Lea are - well - assisting. Ron Williams, Don Cull and Bill Flora are bug shooting in the background.

• Ron Williams found a marginal card that caused another card to overload until the machine warmed up. Apparently a transistor base was not going high resistance when the transistor was cut off. We need Tim to fix it Saturday as there is no more spares of that type.

• Bob Feretich brought in a large (2 foot x 2 foot x 6 inches) sheet metal box containing his part of the Tape System Tester. Bob is doing the logic (TTL) and Grant Saviers is doing the level shifter part of the total effort. This is to help check out both the 1401 Tape Adaptor Unit and a 729 tape drive. Bob says part of the game is to round off the very sharp TTL voltage swings because the 729 cabling system is not well terminated and IBM used approximately "Gausian" waveforms (well rounded rectangular waves) to reduce the effect of reflections in the cabling system. Both the forground board and the background boards are involved. The forground board is covering two power supplies.

• Bob Erickson and Glen Lea returned the Visible Storage 077 to its rightful place. Well, most of it - it now contains some badly worn primary and secondary feed needle bearings.

• I don't know how to say this. Ideally we wear white gloves while working on artifacts. You will notice the Glen Lea is not wearing white gloves as he is using a 2x4 to help pry up on this 077 assembly. Hmmmm. And is that a mallet in Bob Erickson's hand ?? Dag Spicer, you didn't see this!!

• Don Cull, Bill Flora, and Ron Williams worked on the 1402 card reader interface - I couldn't figure out what.

• Bob Erickson and Robert Garner with the Visible Storage IBM 604. Bob used to fix 'em :-))

Present were Ron Williams, Bill Flora, Bob Erickson, Tim Coslet and Ed Thelen.

• Is this a good time for "True Confessions" - that was a TV show wasn't it? OK - We had a "spare" 1401 Operator's Panel - with a problem. For some reason, someone painted the back of the panel white - so densely white that verry-little light would show through. It was totally useless because the 1/4 watt front panel indicator lights were invisible - OK - we didn't try a totally dark room.

  And someone had trouble seeing the panel lights through the panel that is installed on the 1401, and drilled about 6 holes through the panel - apparently so they could see the lights better, but the drilling removed the printed digits that aided operator interpretation of the position values. (And looks weird.)

  Various people have volunteered to do something about the white paint - but didn't. So today I decided to do something. We consulted with an un-named CHM volunteer, who advised, that if we were going to do something, to use GOO OFF - from say Orchard Supply. This was obtained.

  I did the job outside in the open air and -
  - good news - cleaned off the white paint
  - bad news - localized alarm red under the white came off also
  So we will probably place thin red cellophane on the back side on the alarm locations.

  The front of the panel shows signs of rough wear - and some areas looks less glossy than other areas.
  Allison Ackbay was in the building so we asked what to do. She looked at the panel and said - The museum will probably - was it re-surface - the outside of the 1401 system when we are done, and to leave the front surface of the subject panel alone till then.

• Tim Coslet fixed the bad JHxx board discovered by Ron Williams last time. The problem was indeed the diode the Ron has suspected. The diode when removed from the circuit exhibited a loop in the V/I curve - like many of the bad transistors. No one has explained how this loop can happen as the driving frequency is 60 Hz and no reactances are present that should do that at 60 Hz.
  Some bad transistors exhibit a curve that Tim calls a "peanut curve", bent, loops on both ends, narrow in the middle. We have a number of circuit savvy people, and none can explain the loops - could there be a thermal factor we are not aware of???? Tim also fixed three QD cards.
• Bob Erickson worked on the 077 collator. He replaced a roller and a card deflection relay/solenoid that directs cards into one pocket. Grant Saviers, we need help with washers.

• But you really wanted to know about the 1401, the 1402 card reader, Ron Williams and Bill Flora. Ron and Bill are struggling - apparently with the undocumented overlap feature that they are not familiar with. They have scoped and timed the problem and have a clearer understanding of the failure of the second CardRead after the first CardRead. As best I understand it - Bill Flora tried so hard to explain it to me - The normal 1401 waits until after the Card Read (and other) operations are complete before executing the next instruction. This machine with the OverLap Feature continues executing instructions before the CardRead instruction is complete. There is a problem about a ReadCardPrintLine instruction as the printer starts before all the data is in?? Forgive me - it seemed to make sense a few hours ago. And there is the blue Unknown Switch back of the Customer Engineer's panel that looks like an un-official local add-on. Unfortunately Arnold Schweinsberg didn't remember what that switch was for a year ago. Is that related to the problem? The problem does not change regardless of the switch handle position.

• Well - how to recover from the party - and it was non-alcoholic yet! Present at WORK today were Ron Williams, Bob Erickson, Tim Coslet, Bill Flora, Allen Palmer, Ed Thelen, and new volunteer Gordon Andrews.
• Gordon started helping Bob Erickson - but quickly remembered that he liked electronics a lot better than mechanicals - and joined Tim Coslet in fixing four bad SMS cards.
• Allen Palmer realized that the weak torque in the 729 tape reels that plagued him last time is due to worn clutch brushes. These 1/4 inch diameter carbon/graphite rods need to be replaced. The checked the clutch brushes in the four other 729 drives - and they are all in poor condition - either too short to function or just about that way. Grant Saviers has been requested to come up with a solution. (The usual motor brush has a rectangular contact surface.)
• Ron and Bill continued to struggle with the Instruction Overlap feature in the 1401 -
• Bob Erickson is fighting a bearing alignment problem on several of the rollers in the 077 collator. Tightening up the bearing housings to the big side plate causes the otherwise loose rollers to basically jam. After anguished consideration Bob is going to use 5 mil shim stock to cock the bearing housings at a slight angle - no one is delighted.
• Ron Crane is helping Dave Dial of CHM with the sound system in auditorium.