I always see suggestions on using a multimeter. Im specifically looking for one geared towards PCB mapping and testing. Tracing signals and testing wiring. Anyone know one?
I can tell you what you probably need to know rather than poking around for a guide, so I’ll try that.
If you need to follow a trace or wire, you likely need resistance testing. Or, if your multimeter has a beeping continuity test, even better. Be sure your PCB is not powered in any way when you test resistance or continuity.
If you need to follow a wire or trace, then there will be what we call continuity between the two, meaning the connection is continuous between two points, or that is doesn’t disconnect anywhere, nor is there any sort of resistance or component separating the two points. If you set your multimeter to resistance (any threshold), and point both probes on the same wire or trace, naturally, the resistance will be 0, which means it has continuity between those two points. If you have a beeping continuity tester, when both probes touch the same wire or trace, or anything electrically connected (whether intentionally or not), it will beep, instead of dropping the multimeter to 0. This is handy because you don’t have to look at the readout to know if it is continuous.
This is nice because every button (in common ground setups) will touch one ground wire, the other wire will be a signal wire, so there will always be continuity between one side of the button and ground. The other side can be followed by placing one probe on signal (such as 2P on a Cthulhu), and testing wires (only takes a second a piece, tops) to see where is goes to. Or, if you’re trying to follow a trace, keep one end on your multimeter to something connected to the trace you want to follow, then probe around with the other probe until you find continuity. Then you know where the trace is headed.
Unless if you needed something different to look for, then let me know, and I’ll try to get back. I couldn’t tell very well what exactly you wanted. But there’s other things you can test, too. Continuity is just the handiest thing to have.