I'm working on a Black Belt that has led a very hard life.
The biggest problem is that the controlled lamp fuses are blowing immediately on power up. This only happens with the playfield plug connected to the power supply. So far, so fairly obvious: there's a wiring or socket problem on the controlled lamps under the playfield.
I have a few questions:
1) Solenoid expander board is wired in an... odd way - the markings on the playfield show that there should be two diodes mounted under the lamp. The marking on the playfield is for a Zener, but I do not see the Zener in the schematic. One of the two diodes shattered into dust when I attempted to move it slightly to read the marking underneath. Should these be Zener diodes?
2) The schematic appears to show the striped ends of the two diodes mounted under the lamp pointing towards each other, but the playfield is not marked this way. How should those diodes be mounted (and where)?
None of the feature lamps are working, which kills the solenoid expander board, and I'm close to my wit's end.
I've checked the diodes and lugs for wires touching or broken wires on all lamps and switches. Found some bad diodes, replaced them. No change in operation.
I've looked for funkiness in the plug, broken wires and so forth on the power supply playfield connector. Fuses blow if the playfield is unplugged (by connector under playfield), but the power board playfield connector is installed.
I don't have any photos, unfortunately, but if anyone has some suggestions, I'd greatly appreciate them.
Should I just go in and replace every single socket in the game? I've just about reached that point...