LED and switch failure

[Luke Shiner]

My PiDP-10 has developed an issue about a year after building. 2 LEDs associated with bit 3, along with the bit 3 data switch, and 3 LEDs associated with bit 21, the data switch for bit 21 and the address switch above it have all stopped working. The Run and Program stop LEDs are also not working. Everything else seems fine.

It seems unlikely to me that bot the LEDs and switches share a common ground. I'm wondering if they share a GPIO pin?

If anyone has any information that could help me diagnose the issue I'd be very grateful.

[Luke Shiner]

Update:

I disconnected the switch PCB and the problem with the LEDs persisted so I removed the LED PCB. Some wiggling made the LEDs work correctly intermittently. More experimental wiggling led me to the Raspberry Pi header, putting pressure on this in a certain direction fixed the issue. Looks like I'm re-flowing some solder joints tomorrow. Can't say I'm surprised given the mechanical pressure that header is put under when the Pi is put in and taken out.