Just an update. I stopped over his house and took a look at it a couple weeks ago. I tested continuity back to the opto board. That tested fine. We replaced the optos and tested for good measure that they were lit (they were). I disconnected the switches off the CPU board and tested all the rows and columns there, and they tested good. At one point all optos and switches were working.

I believe the CPU row and or column connectors may have some corrosion, I recommended he replace those, and also I am pretty certain the similar connector on the opto board is suspect.

Strummy, please post a couple pictures of the front and backs of those connectors. Also someone post a link to the connectors and the tool to punch the wires down. This is not a typical GI style connector, it uses the much finer small wires. I don't think pinballlife has them. I'm guessing maybe greatplanes electronics but don't want him to purchase the wrong connectors.

Update, wires are crimped and there is continuity to the Opto and receiver. I tested the opto board with jumpers and with jumpers the board tests OK. I can't for the life of me get either min playfield opto to work. The transmitter is lit up, but they don't work in test mode.

Measured 11.70v at the optos that aren't working.

Thanks I have the same tool. The punch is NOT the problem. I have continuity all the way from the opto to the backside of the opto board for all wires going to the opto boards. I have tested the opto driver board and it tests fine.

Fixed. Problem was 2 bad opto receivers. I had already swapped them before but either the new ones were bad, or something shorted them. I replaced the opto driver board with a new homepin one. I'm wondering if the questionable original board was bad, and blew the new receivers.

Either way it's working.