Ok. It shows the same pattern every time the machine starts up as well, by the way.
The next time I’ll socket all the ICs, no matter what the build instructions tell me to do.
Replaced IC 11. No change. I did damage the pad for pin 13 of IC 11 which resulted in all kinds of weird LED flickering. Fixed this with a wire between pin 26 of the MCU and pin 13 of IC 11.
Maybe I damaged a pad or trace on this board? Based on the behavior in the image at the top above, where should I start looking (assuming this could be the case)?
As I said, the LED pattern is random, so it doesn’t mean much… I’m afraid there’s no test you can do without a scope or logic analyzer…
Next I would desolder (remove) LED 10 and doublecheck the corresponding resistor.
@pichenettes Maybe I’m missing something (very likely), but the pattern isn’t random at all. The LEDs function as intended and indicate the correct page, except that those that should be off are a very dim yellow, and LED 10 is always brightly green.
I removed LED 10 as @cj55 suggested. Turned out there was a short between the LED and the uppers side of the PCB that wasn’t visible with the LED in place. I feel terribly silly for not trying that first, but happy to have it fixed.
Thanks everybody for your help and sorry for wasting your time. I owe you all a beverage of your preference.
Yay! I was right
Good you found and fixed it!