Hi. I just assembled my Alpha CLock Blue and when I plugged it in for initial testing, I received only ‘Hell Worl’ – the last LED display appears to be non-functioning. I have double checked my solders and my orientation and all seems to be correct. Anything else I should check? Is it possible I just have a bad LED? Or is there another issue I should be looking for?
A bad LED display is possible but unlikely. You can try swapping two of the LED displays — carefully — to verify. If the entire digit is out, the most likely situation is that transistor Q1, which turns on that LED display, is not turning on. Check soldering and orientation of Q1, as well as RP6 and U5. Check with the schematic if you need further reference for what’s what.