I am having an issue with my TZ where the opto switches on the top and bottom of the mini playfield are not registering. The rest of the switches in that column do register. I tested continuity from each wire on each transmitter and receiver back to the playfield harness and it is good. Also, when a ball it shot up the right ramp, the diverter will grab it and drop it onto the playfield, then a few seconds later the diverter will fire again with no ball on the ramp. Not sure if that is related but hopefully it is. Any guidance on where to go from here would be appreciated. Thank you!

It seems odd both sets of optos would have failed at the same time. Is there any way to test them? I think the issue with the diverter was due to not hitting a switch afterwards. Thanks

I did a little more digging...went ahead and reflowed and recapped the opto board under the playfield and it didnt make a difference. The manual says that when the receiver is unblocked, the voltage on the two wires should be less than 1v. When blocked, it should be 13-14v. The two of mine that aren't working are showing 13.5v when unblocked. I cleaned both sides and it did not make a difference.

i subbed one of the known working opto receiver pcb's and the issue followed the one i removed from the mini playfield. looks like at least one of them is bad. ill replace them both and that should do the trick.