How do trace switch problems

[steve green]

Greetings, I am a retired IT guy from Canberra, Australia.

I recently finished building the PiDP-11. During the switch testing, I found a few issues. During the LOAD ADRS tests, a few address switches behaved incorrectly. Switching either address bits 15 or 16 results in bits 15 and 16 being lit after LOAD ADRS is pressed. Switching just bit 3 illuminates address bit 4 after pressing LOAD ADRS. Switching just bit 4 and pressing LOAD ADRS does not illuminate any LEDs in the address display.

I have checked my soldering, and can see no obvious bridges or dry joints. Everything else works just fine. But I'd like to fix this if possible.

Any suggestions on how I can debug these problems? I have a multimeter so I can conduct basic continuity tests.

Thanks in advance.

Steve

[steve green]

I just diagnosed one fault. The LAMP TEST lights all LEDs EXCEPT address LED 3. So that's my first place to look.