On 8/29/2018 9:49 AM, Kyle Owen via vcf-midatlantic wrote:
Why would ohming out this board not yield a 100% correct schematic? I see no tricky components that would confuse an ohmmeter except the address switch, which could be unsoldered.
Many of the signals go under the ICs. Sometimes, you can hold to a light and see through the PCB and validate where they go, but other times, I have missed wires connecting to more than 1 pin of the IC under the IC. Ohming, if applied verbosely for each signal around the IC compared to each IC pin, should find all of them, but I don't think I would promise 100% perfection without spinning a PCB and testing the completed unit. Maybe everyone else is better at ohming out boards and the hidden signals under ICs never bother anyone else, but I've gotten hit twice by them on two different efforts. Jim