I have been banging my head on this one for weeks. Hopefully, a Gottlieb pro can help. Freddy Kruger is living up to his name.

The game I'm working on is doing two things.

One, the Jaw(Sol14) open coil energizes when I test it from the menu, or if I test the Mouth VUK(Sol12) coil from the menu. Not sure if it's supposed to do that.

Two, the big one. If the Mouth VUK(Sol 12)is in its circuit, it blows the in line 2A fuse. That fuse goes to another coil, the Top Left VUK(Sol13), but that coil doesn't pop it. I've checked my coil on the Mouth VUK, and it's good. The diode on it is good. The driver board SHOULD be good, as I just replaced it with a Rottendog (the old one was lifting traces with the slightest touch of an iron).

I got to the point of using my Logic Probe, but that hasn't given me any hints. Looks like the CPU, U1 outputs are good, and the inputs on the Latch Chip, U7, on the Mainboard. It looks like things go wrong after outputting U7 to the Driver Board Buss. But, instead of seeing a Hi stuck or similar, I'm seeing Lo, Hi, and Tristate values form the logic probe. But once it goes through U2 on the Driver board, everything is registering as a Pulsing Lo.

I'm lost. I expected to see stuck a Hi on Solenoids 12, the Head VUK. And on Solenoid 14, I thought I'd see something tying into what is making it energize with 12.

I tried making a map from the Solenoids to the CPU, showing the Transistors and Busses taken to get from A to B.

If this is confusing, I'll try to rephrase it later. Maybe dig in the forums for anything relevant. My head is killing me.

coils (resized).png

In the chart, Lo and Hi are self explanitory, TS means Tri-stating, and LoP, HiP, and TSP means the Logic Probe was pulsing

So I went way overboard on troubleshooting, but given what all I tried I'm not too embarrassed about it.

I ended up buying new coils for the left VUK, mouth VUK, and jaw coil. After switching the mouth VUK coil out the issue stopped finally. So somehow the original and first replacement coils were both bad. I've had bad coils before, but that was just weird.