Hello. I purchased two 4x4 button pad PCBs (COM-08033). I installed one into my project no problem at all. It works perfectly!
The second one, however,is a different story altogether. The switches work very well, but the LED circuitry appears to be messed up. At the heart of the problem is that some LEDs illuminate when they’re not supposed to. Mostly the colour green. And even when all I have are the column pins connected.
When I run the example code in the hookup guide to cycle through the LEDs, even if the only colours connected to each LED is red, some will light up green even when it’s not their turn.
I did continuity tests to see if there were any shorts somewhere, but there was nothing out of the ordinary. I’ve tried swapping out some of the LEDS., connectors, I’ve swapped the connections with the working keypad, and the issue always follows the keypad. I cleaned the PCB with 99.9% Isopropyl. No improvements at all. Outside of completely removing all the LEDs and starting over again, I’m out of ideas.
Is the board defective? Are there rogue traces making connections where they shouldn’t be? I’ve been troubleshooting this for hours and I’m at a complete loss. Any help would be greatly appreciated.