Recently, when I turn on my No Good Gofers for the first time that day, during the first game or so the right popper (under buzz) keeps trying to kick out a ball that isn't there. The software makes the "knock knock knock" noise and the flasher lights up, so I don't think it's a problem with the solenoid. After I play for a while it goes away. I don't have to hit a ball into that lock or anything (I don't think). Obviously this is really hard to troubleshoot... When I check it in test mode it seems to work fine. I've cleaned the optos and put them back and it's still acting up.

Anyone have any ideas? Is this indicative of anything about to fail? I'm wondering about my opto board. Right now it's not a big deal at all (even when its acting up it doesn't affect play). I've also had some very intermittent (ie, only happened a few times) issues where a putt out, left (buzz) lock, or hole in one doesn't register, but I think that's the ball skipping over a physical miniswitch and unrelated.

Thanks in advance!
Josh

Reflow on the opto board or where the wires attach to the opto itself? Both halves of the opto?

Thanks for your help!

I finally got around to doing this last night (replaced all 4 transmitters and receivers) and I'm still getting the same issue. Any ideas where to look next?

I had another thought, which is that the wheel, which also uses optos, occasionally reads incorrectly as well, also usually at the beginning of a session. I purchased the new board from greatlakesmodular but it still has the issue sometimes.

I was going to see if either of the wheel optos shared a component with either the right popper or right popper jam optos, but I can't find a diagram anywhere. My next step I guess will be taking the 16 opto board out and trying to trace where these 4 switches go.

Any other suggestions? I figured the fact that the behavior stops after warming up would be an important clue, but I don't know what component that would point towards.

Thanks in advance,
Josh

I *think* I resolved this and wanted to post for anyone else with a similar issue.

As this was a very sporadic problem and didn't interfere with game-play I ignored it and figured when it got worse it'd be easier to troubleshoot.

Then about a week ago when we were having company over to play pinball (of course), the game started resetting when double-flipped until it was warmed up for a while (like an hour or more). So after testing it I replaced the thermistor, which not only fixed the resets but also (seemingly) the flaky opto!

I never got around to checking it, but I suspect that if I had done as @mschonbrun suggested I would have indeed found that the 12V line was low until it warmed up. The opto never triggered in switch test mode, I assume because it only triggered when the flippers or other solenoids dragged the voltage down.

Thanks for the advice everyone!