Hey guys, I'm doing a my first restoration on a Williams Space shuttle and I am having an issue with the lamp matrix. Currently all lamps work other than row 1. I have tested the plugs going to the play field and found that the wiring to all the lights is good so my issue is somewhere between the PIA and the output. I connected my multimeter to 1J61 and 1J71 with lamp test mode and saw no fluctuation of voltage, IJ62-IJ68 and IJ71-IJ78 all pulsed. I checked the diodes and resistors on the board associated with that row and didn't see any values out of the ordinary. Does it sound like I need to replace the PIA or could there be something else that I am just missing.

Thanks!

Vid thanks for the advice I finally got my logic probe and found the 7406 is not processing the signal properly. Pin 3 (input side) is pulsing properly so the PIA shoudl be fine but Pin 4 (output) is constantly low. I'm going to replace the 7406 and see if thats the issue.

Just as an update, I replaced the 7406 and it fixed the issue however I lost two lamp rows during the process so I'll be replacing the TIP and Darlington driver this week.

Thanks for the assistance Vid