Last week the ship started registering random hits. I felt like it happened at times when the ball triggered the "skill shot made" (switch #60). The "ship made" opto switch is #61. They are the same opto board. In switch test I could not reliably produce any error, but occasionally when I triggered the "skill shot made" (#61) it would register as "ship made" (#60).

So I assumed it was that I opto board and replaced it today. I played about five games and everything seem to be fine. Left the machine on for a few hours and came back to play again, now both switches are acting crazy. In the test mode the switch for the ship made is not even registering about half the time, and when I trigger the skill shot made switch it either does not register, it registers correctly, or it registers for the other switch (ship made). And if I just let the machine sit in switch test mode about every 20 to 30 seconds one or the other switch will activate spontaneously.

Just in the time it took me to type this one or both the switches have gone off several times in switch test mode without me touching the machine.

While I wait for advice I'm going to reseat all the wiring in the one IDC plug that goes to that board and see if that makes any difference. What should I do next?

Thanks Lloyd

I'll do that now and report back. And yes, already cleaned the optos

Reflowed the solder on all pins. Slightly spread the pins for the opto sensors so that they fit tightly.

Switch test initially ok. Let it sit in switch test mode for about 10 mins and no switches randomly activated as they had done before. Then I played a game and by ball 2 started having random registered hits on the ship again. Sitting in switch test mode again it started showing one or both of those switchs firing unprovoked. In switch test mode I have wiggled and moved each opto plug wire without seeming to recreate the issue.

Took it out of test mode and when it went back to the active game appropriately kicked a ball into the shooter Lane and then the ship registered hit after hit and sunk (ball not even in play). So many phantom hits on the ship that it defeated Davy Jones.

Here is the one connector. I rested the wires earlier with a proper tool. I feel like they look to be ok

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Disconnected and reseated all plugs about 20 minutes ago. Switch test was without errors. Played a couple games and switches seemed to be working properly. Then left it sitting in the switch test mode for about 10 minutes to see if I would get a random firing again and so far that has not happened.

Not convinced that the problem has been fixed since it initially did fine when I first replaced the opto board.
I'll leave it sitting in switch test mode for a while and then try a few more games later.

That makes sense to me. I just played about four games with no errors. Right before I did that I spread the pins slightly to make plugs grip a little tighter. If it starts up again I will see what I can do to make them grip the pins better. Thanks again for all your help.

Ok. Had not posted back in a week because I was waiting on new opto sensors. Installed those today.

So far I have: (in this order)

Cleaned all 4 opts
Replaced the opto board that services the 2 switches. Actually used 2 different replacement boards
Reflowed the solder on the opto board
Spread slightly the pins for the opto sensors and hot glued the plugs to the board
Replaced the opto sensors today

Still have the same issue, buts what is interesting is the sequence in which it fails after each repair is exactly the same:

As soon as I complete a repair I start in diagnostic switch mode

1. Switch test says everything works fine, even if I test all switches dozens of times
2. Start game, everything works until about the 3rd ball then start getting rare random hits on the ship
3. Then the more I play the random ship hits get more frequent, especially if I am close to sinking a ship or in Davy Jones multiball. I don't think it's ever happened on a ship that has had no hits.
4. Then after seeing random ship hits if I keep playing that opto "ship made" suddenly stops registering when it is actually triggered, but the opto lights are clearly still on.
5. Go back into diagnostic switch test at that point and both the "ship made" and "skill made" switchs do not consistently register, and triggering the "skill made" switch then often registers "ship made". And if I let the game just sit in the diagnostic mode the "ship made" switch will just randomly register 2-3 times over 10 minutes.

If I turn off the game and then restart a game after a bit the cycle repeats itself. First few balls of the game seem to play fine.

Bump for ideas

I appreciate all the suggestions.

Yes, the Opto switches have been connected correctly. Between changing out the boards and the opto switches they been disconnected and reconnected multiple times

And yes, (I did mention it much further up in this post) I did reseat all the wires in the IDC connector and have resoldered all those plns as well. And in the switch test mode I have wiggled all of the opto sensor wires as well as the wires in the main IDC plug and cannot duplicate the errors, yet, as I said above when the switch starts acting up if I leave the machine setting in the switch test mode that one switch will periodically randomly activate with no manipulation of any kind

So actually thought about this yesterday. So last night I removed and reseated each plug on the CPU associated with these switches. Switch test was fine and played 2 games with no noticeable issues. Moderately encouraged but of course not convinced it's fixed until I get to put it through a few more games.

Pulled and replaced J1, J6, J12 and J16. Manual says J5 has a common return for both switches but I could never locate J5. The only J5 I could find was for the ribbon cable to the DMD.

If it takes care of the issue I have no idea which one it could have been though.

Would be happy to but I've never moved a thread. Instructions?

Thank you

Yes
This actually took care of it. It's had no issues since. It's just a sketchy system that fails with the least loss of continuity.
But it took me months to fix and I replaced a lot of parts before I addressed the issue at the boards instead of on the Playfield.

Good luck.