So game worked just fine then it went bananas. Solenoids popping, balls firing out all over the place, credit dot, motor errors etc. Found F116 (12V supply) fuse blown. Replaced it and for a couple minutes things were fine (escept VUK is constantly firing every couple seconds), but then bananas again. After some digging and troubleshooting I THINK I have it isolated to the J116 plug. If this is unplugged from the power driver board, fuse doesn't pop. If it is plugged in, fuse takes about 30 seconds before it goes. you can see it slowly turn orange then pop. Any ideas?? Not sure where this plug goes. Seems like it feeds the coin door circuit board, but it loops in and out of that and off to where I am not sure.... its driving me crazy.

Thanks for the reply...So a little more info, if I measure voltage at the fuse, I am getting 5VDC. Also, what is strange is that if I measure voltage at the coin door board, I get 12VDC. with the J116 plug disconnected. I am thinking something is wired up incorrectly? if this J116 is supposed to be 12v to the coin door, how can there be 12v there if J116 is unplugged? With this plug disconnected, it seems that none of my Optos are powered up anymore. Or at a minimum my through opto boards.

OK dug a little more....

I have 15V (is 15V a problem?) at the output of J116 and J118, clearly these 2 outputs are in parallel. J118 must be feeding the coin door loop, and that seems fine. J116 is feeding lots o stuff according to the manual...ugh. Bridge Driver board, Motor EMI PCB (wheel motor), Plane Gun LEDs, Through LED board, Through photo transistor PCB, 10 SW opto PCB, Idol Opto PCB, Motor EMI PCB for idol, etc...

where does a guy start??

need more fuses at this point....

another item to note, when J116 is connected, Rows 2 and 3 show as shorted when the game boots until the slow blow fuse goes...

Prior to this, row 1 was also shorted. This was caused by an aftermarket spotlight that was powered via a GI lamp with alligator clips. One of the clips was shorting the +- together. Removed the clips, and row 1 is good but 2 and 3 still shorted. Could this have smoked the U20 chip?

will try disconnecting the coin door harness and interface board tomorrow.

Update,

I have this isolated now to the 10 Sw.-Opto PCB. If J1 is disconnected then no more fuses blowing. When I plug it back in, it takes a second or 2 but then rows 1, 2, 3 show as shorted.... thoughts?

update,

Now i am down to the board being bad. is I activate the captive ball Opto, I get Rows 2 and 3 shorted. Same result if I disconnect the optos for the captive ball...does it make sense that the board is bad? Any pointers would be great!

So, finally figured this out. Bad Opto Board. swapped and all is right in the world. no more fuses blowing, no more issues....IJ is back