I was playing a game and after completing the 5 drop target bank the machine started screaming and the f2 fuse blew. The exact same thing happened once before and I figured out I had a pop bumper that had shorted. Once I fixed the short all was good.

Because it happened this time immediately after the completed drop target bank I checked it for a short. What I found was it was shorted because the coil had rubbed against the bracket housing and therefore shorted. I simply wrapped the coil with some electrical tape and the short is now gone. However, I'm still getting a blown fuse every time I turn the game on. Here's the rest of what I have done.....

I unplugged the connector from the driver board and the game turns on and doesn't blow the fuse.

I then began checking all the coils associated with that connector. I found a broken diode on the kick out hole coil and replaced it.
I removed the diodes from the drop target bank that was shorted and tested them, they tested good.

Using my meter I checked all the transistors and all tested good. (TIP 102). I tested the smaller transistors and one leg would give me a correct reading while the other leg tested .2 something. This was consistent with all of them. Clay's guide indicated that would be a possibility and that transistors could test bad and still be good.

I then removed all the wires from the coils associated with the connector. The fuse did not blow.

At this point, I turned the game on and I began to touch the wires back to their appropriate coil post to see when the fuse would blow to isolate a possible bad coil.

What I learned is that every time I would momentarily connect the wire to the coil lug the coil would fire and stay fired. This stayed consistent with all coils tested.

So what I assuming is when the game is turned on all those coils are firing and staying engaged therefore blowing the fuse.

Could my TTL 74XX chip be bad as a result of the shorted drop target bank? Thanks for any advice and tips......I'm on my second order of 2.5 amp fuses!

Sorry for the lengthy description, but I felt I needed to share what all has been done to this point.

In short, all of the solenoids associated with connector 2J11 are locking on when the pin is turned on which is blowing the f2 fuse. Any help appreciated.

Thought I would update this thread hoping it may help someone with a similar issue. The problem was the coil on the drop target bank. The vibration of the bank caused the coil to rub against the metal housing of the bank. It rubbed through the coating on the coil wires and made it short out. I simply put a piece of electricians table between the coil and the housing.

I isolated it by disconnecting the high voltage coils connected to F2 one at a time till it would boot up and not blow a fuse. I then knew it had something to do with that particular one.