Help diagnosing an issue

[lowrybt1]

Hello,

I'm inviting any and all diagnoses and suggested corrective steps to help me troubleshoot an issue with my C8P. Here's the situation:

* C8P contains a 505B, 540B, Klyball D-13 ver 1, A15 board and Glitchworks 64K RAM board. An OSI 542 keyboard is connected to the A15 and 540B board.

* The last time I used the system was 4 months ago and all was good except for some spotty action on the keyboard

* Two months ago, without powering up the system, I disconnected the 542 board and did a thorough clean -- pull and resocket IC's, careful cleaning of contacts, reseating of cables connecting back to the 540B. I reconnected the 542 but did not power-up the system.

* *Today, I powered up the system and got to H/D/M. Pressing any key results in 0000 1B showing up. Additional keypresses give no visible effect, register displayed does not change. After a while, I swapped in a spare 542 and got the same results.

* Next step was to pull and reseat the boards in the C8 case. Something changed. H/D/M show-up and now any keypress generates 0000 02. After that initial key press, additional key presses have no influence, the display 0000 02 stays the same.

Thoughts on next steps? Thanks, Tom

[lowrybt1]

After swapping the keyboard sets again, it's working. I'm guessing that a pair of the AMP pin connectors at the end of the keyboard ribbon cables was out of alignment. I also determined that one of my 542 keyboards is non-functional. Is there anyone on the forum who does vintage equipment repairs?

Tom

[lowrybt1]

After swapping the keyboard sets again, it's working. I'm guessing that a pair of the AMP pin connectors at the end of the keyboard ribbon cables was out of alignment. I also determined that one of my 542 keyboards is non-functional. Is there anyone on the forum who does vintage equipment repairs?

Tom