UPDATED:

The Issue..

1. Sometimes the hand will move into the lanes when it doesn't have a ball.
2. The VUK for the hand will dry-fire, when it has no ball.
3. The lane diverter that opens and closes gaining access to the hand VUK sometimes opens, when it should not.
4. When I turn on the game it will cycle all the balls
5. When i turn on the game, the hand will adjust several times. more than it should.

result: The game will start adding balls till I have a 4 ball multi-ball...

What I have done:

1. Adjusted Ball in hand switch
2. Removed ball in hand switch "common bug fix".
3. Replaced damaged micro-switch on ball-block target for hand.
4. Ran tests, micro-switch for VUK for hand works, as well ball in hand and so on.
5. I had interlock switch issues. So I removed the interlock and installed a on/off toggle switch.

Questions:

1. Could the diverter that pivots outer loop to hand VUK be causing the extra balls.
2. Could the opto for the VUK be messing up.. thinking it has a ball and cant find it.
3. I had issues with the interlock door switch... could some kind of power drop from the interlock power switch cause this?

Update: I am able to get a game to play.. but during the game I get random extra balls... As well during video mode the hand moves and I can hear a solenoid fire and at one point it will kick me out of video mode.

Will do that now. Another update. While holding both coin-door switches closed with my hand. First ball was ok.. I let a ball drain.. Then next ball it shot out all 4 balls and random modes started one after another.

Bottom coin door switch registers. Top coin door switch is not registering. However, the top switch should not register in switch test mode. Sounds like I have a complete different issue.. Not coin door switch related.

Maybe optos in the ball shoot?

update: Looks like the switch on the block target by the hand is falling apart. Typical issue with micro switches where the plastic ball joint wears out and the switch handle wobbles loose. Could this be giving me the random new balls. I assume It is not registering the ball being in hand or it is missing based on that failed switch. It works, but I assume it is failing randomly. As for the interlock, I removed both switches and re-seated all the connectors to that switch. So far, no interlock errors.. Just random balls. "I hope it is just that failing switch". I dont have any extra micro switches so I need to order some.

If I am correct,.. I had:

error: interlock door open
1. Loose door switch connector

random extra balls.
2. Failing switch on the block target near hand.

In this case, it is a block target... I figure since sometime when the target is hit it either stays open, but the target is down. Or some variation of that which is showing up as ball missing or something else. I will remove the switch lever since it is about to die anyway and see what happens.

update: Ok, I am confident my extra balls are from this switch. After this last experiment it makes sense. I will get that sorted out and report back once I have a new micro switch.

Update: Installed new micro-switch on the hand-block-target. Not only was the lever falling off since the plastic ball joint was gone on one side the ground wire was dangling. Fixed that and things started to run better. My one interlock switch needs to be replaced. nothing wrong with the wires. It is the switch itself. "QUESTION" The door switch "not the one holding all the voltage". To test cant I just connect them two wires on the switch, that way if I ever get an interlock warning I will know it is something else before I go and buy a new switch.

However another issue... seems my "ball in hand" switch is messed up. The hand thinks it still has a ball. I removed the switch, everything is fine as well it registers fine. However, it seems to get hung up after its first ball and doesn't release the leaf switch. "It is a little warped/bent" First time with this kind of leaf switch. It is a rectangle with a rectangle hole in the middle. The ball stop, which is what the ball hits when the magnet sucks it up sticks threw this hole. But I cant get the switch to sit right without getting hung up "randomly" between every ball grab.

Part # is A-20612, only $8 but sold out on planet earth. I would buy a new one just so I had one that was not warped.

update: Ok... So I just went ahead and unplugged the "ball in hand" switch. Everything seemed to play normal... I read that this was a common dirty fix for JM... however, on my second ball... It shoots out all 4 balls now. So, in my case I guess I really do need that switch.

update: sorry for all the updates. I managed to fix the switch. I removed the magnet assembly and was able to bend the switch properly so it doesn't get hung up. So far, no "ball in hand" error. If it continues to happen, while the switch is working properly. I suspect the opto for the ball eject for the hand could also cause the hand to think it has a ball.

anyhow... It is running normal. that is all for now

Awesome, thanks for the detailed answer. I figured it was just the switch matrix but wasn't sure. I may just wire the door open switch to a toggle switch. I have a huge box of on/off toggle switches.

update: tried a game tonight... Hand starts moving, VUK that shoots the ball up to the hand starts firing blanks and then it just starts shooting out new balls. "opto? is it thinking it has a ball in the hand VUK?

service: I get ball in hand errors and then some other hand errors. I go into hand self test and it fails.

update: removed the interlock switch and connected the wires to keep it closed... Still get a random Interlock Warning "Sometimes". So, I don't think it is the "ball in hand" switch, or the opto. It must be something else which is causing an interlock error.

update: Even more confused... Had several good games. But back to random balls and dry fires from the hand VUK. I updated this topic with:

UPDATED:

The Issue..

1. Sometimes the hand will move into the lanes when it doesn't have a ball.
2. The VUK for the hand will dry-fire, when it has no ball.
3. The lane diverter that opens and closes gaining access to the hand VUK sometimes opens, when it should not.
4. When I turn on the game it will cycle all the balls
5. When i turn on the game, the hand will adjust several times. more than it should.

result: The game will start adding balls till I have a 4 ball multi-ball...

What I have done:

1. Adjusted Ball in hand switch
2. Removed ball in hand switch "common bug fix".
3. Replaced damaged micro-switch on ball-block target for hand.
4. Ran tests, micro-switch for VUK for hand works, as well ball in hand and so on.
5. I had interlock switch issues. So I removed the interlock and installed a on/off toggle switch.

Questions:

1. Could the diverter that pivots outer loop to hand VUK be causing the extra balls.
2. Could the opto for the VUK be messing up.. thinking it has a ball and cant find it.
3. I had issues with the interlock door switch... could some kind of power drop from the interlock power switch cause this?

Update: So far, it seems like it was in fact the Trough Opto. The transmitter "I think thats the yellow one" was bent and it was not facing the hole properly. I bent it back so it would shoot light in the correct direction. I also reseated all the connectors on the opto boards. Both transmitter and receiver boards. so far, game boots without shooting balls and without the hand going ape shit. As well, I am able to play a game without any crazy things happening. So far, it is good. But, from its track record it seems to be random.