Tuesday, November 4, 2014

Minor work done, keypunch debugging going very well

Feeling a bit better and spent a couple of hours with the machine today.


Peter Vaughan of The National Museum of Computing in the UK has restored an 1130 system much like mine and has been an invaluable source of tips and shared experiences as I work on this machine. When I was disassembling the feed and read clutches to clean up the lubrication issues, I found a short narrow pin with rounded ends sitting in the bottom of the machine compartment.

Peter recognized it from the description, since he had exactly the same thing happen to him while he was working on the 1442. It is a pushrod that must be reinserted in the feed path mechanism. If only he could tell me where my dropped punch is sitting, all my problems would be solved.


I had very solid progress today. The binary mode works properly, as does the automatic multipunch mode. I discovered a small flaw in the code that was blocking the release function, corrected it I thought, but it wasn't working.

Continuity testing showed me that the signal wasn't getting through my interface box. The wires inside the box to the plug on my box were working, but no continuity through the cable. I finally discovered that pin 20 of the female plug had pushed out rather than sliding over and mating with the pin of the male connector on the box.

I opened the connector, pushed the pin back into place, reassembled the connector but once again, no connectivity!  Clearly the pin is not latching as it should into the connector body. The next time I work on this I will open the plug housing AGAIN, but this time chop the wire off the defective pin, toss that pin in the trash, and put on a new pin.


The third board is now more than half done - seven pairs of driver/receiver circuits installed out of twelve. Once again, ran out of daylight or I would be done.

I began repairing the flaws in the first board - I have just five pairs of resistors left to insert. One of the pair (12K) is already installed into the +5V rail, waiting for me to open the hole and insert the other end where it belongs. The 1K resistor need holes for both sides opened and then the resistors installed. This won't take that much time until it is wrapped up.

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