Thursday, September 25, 2014

Finished keyboard, wired interface cables to keypunch, and prepared software for 1132 printer restoration work


I had to partially disassemble the bail contacts to rebend the bail and contacts, but eventually I had it working properly. I took the time to burnish the oxide from the 40+ latch contacts on the bottom of the keyboard, to ensure that all contacts will be made properly for any keypress.
Removing black plate to get to keyboard underneath

Bail contacts detached to get to bails thenselves

Bails with removed contacts at right

Closeup of bails which pivots for certain keystems, touching bail contact plate
Reasembled bail portion of permutation assembly on keyboard
After reassembling the keyboard, I installed it into the 1131 but only hand placed the black plate over it - didn't want to tempt fate if I had to go back in yet another time to tweak the contacts. Turns out that was a good idea. The keyboard is correctly encoding all the characters but also spuriously firing up and entering keystrokes. When it fired, I saw only bit 2 turned on.

A bit of deductive reasoning with the schematic of the permutation unit connections told me that it had to be a specific bail whose gap was too narrow and intermittently made connection. Only a few contact pairs emit bit 2, but only one does so only when the keyboard is in alpha mode but not numeric. That is bail 13, which is right next to the one I was bending in the repair. It makes sense that one might have been disturbed a bit.

I was able to check and adjust the bail contacts without removing the keyboard, since they are on the sides. However, the problems continue. It may be that I adjusted the bails with the keyboard on its side, due to cable length restrictions for the wiring coming out of the 1131, but with the sag of gravity I might need to adjust them better.

I spent some time but it was hard to determine where my extraneous triggering is occurring. It does not seem to be the bails, which makes me suspect I might have a more devious connection through latches that are producing the behavior. To resolve that, I do indeed have to unscrew the keyboard from the 1131 and tilt it up once again.
Latches on bottom of permutation unit, under bails
I cleared up the issues with the latches, put it back onto the 1131 and checked that operation was now normal. No spurious clicks and I walked through every key and character to ensure it was encoding the right characters.
Working keyboard back in 1131, ready to be closed up
With the problems all fixed, I declared the keyboard fully restored and complete. I mounted the black plate and closed up the machine.


I decided to try to adjust the connectors I have in hand, using some wire lead cutters to gently bend them to a slightly tighter fit. I get this mostly right, but some become too tight to slide onto the SMS pins. After a half hour of careful work, I had nine of the twelve punch magnet connections affixed properly. For each problem connector, once I rule out issue on the pin itself, I will cut off the old and install a new connector, gently pinching it, and installing on the pin. This took two hours overall to complete.

Having fixed the connectors, I was able to complete the wiring of the punch cable, joining the read cable I previously wired in. The last step was to install a reed switch on the side of the card lever relay, allowing us to sense when the relay is energized. The wiring was tied down neatly and the keypunch tested to verify that its functionality was not impaired through any wiring foulup or incidental damage.

It is now time to begin wiring the relays and Arduino to the corresponding DB25 connectors. I will put this in a hobby box of some type - time to pick up some connectors and miscellaneous supplies.


I retrieved my hand code to test out the 1132 printer, generalized it a bit, and carefully laid it out so it can be entered into memory. When that is done, I will be able to test the printer.

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