Friday, October 31, 2014

Still battling the keypunch, stalemate tonight, plus more assembly of SAC interface boards


After going over the inside of the keypunch and bending various SMS socket pins and relay panel pins to ensure there are no unintentional shorts, the keypunch appears to be working just fine by itself. I finished wiring up the new keypunch cables I began with better, more secure connectors and larger gauge (lower number) wire. I dressed it well along the panel and made the cable much more bulletproof and production level.

New reader cable DB25 plug - rugged wire bundle

Reader and Punch cable wiring dressed in place on back of wire relay gate inside keypunch

My reader (white) and punch (red) cables ready to plug into the interface box
In addition to replacing the cables and dressing them along the keypunch relay gate, I wired the power brick into the power supply so that it is switched on with the main keypunch power switch under the table. Finally, adding a DB9 extension cable to run up out of the machine, I now had the means to put the box inside the keypunch ready to close up the interface cover once debugging is complete.

Power brick cable converted to lugs to attach to the 029 power supply
Testing resumed but the keypunch is stuck in its state of refusing to recognize a card was registered. I will check over my wiring a bit but I am beginning to suspect this is just erratic operation from relay contacts that still have a bit of oxidation on them. However, I will also recheck the wiring to be sure it is correct.


I assembled more receiver and driver circuits onto the board today. I was able to finish one board and have three more to do. It is slow going to make sure I do it correctly. It has the +5V, +3V and ground power lines attached but does not yet have input or output leads.

One completed board for SAC interface, 12 drivers across top and 12 receivers across bottom


Several manuals are not available on bitsavers or other digital archives, but should be. I slowly (and I do mean slowly) get the pages scanned in between other activities. This manual with more than 180 pages has taken three days elapsed time so far and I am still only at page 150. I don't usually comment on the scanning but realized it was completely sub rosa if I didn't.

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