Still working on an Indiana Jones that I screwed up by plugging in the High Voltage connector for the A/V board into the Driver board J120 out for High Power solenoids. Fixed all but one of the solenoid problems and have posted in another thread the diagnosis, results and repairs required for this royal screw up.

Still have one nagging problem and I'm not sure it's due to my connector snafu, or if this was an issue that's been here all along. The 20V line for the flash lamps measures at only 8.7V DC. And that is with the coin door switch open OR closed. The LED 5 for 20 volts is on, but as soon as I try to start a flasher test, LED 5 Goes out and no flashers will come on. Not surprising given the low voltage on the circuit.

I have checked the voltage at the input at J102 pins 1,2 and 3,4 and its low there too. Only 3.67V AC (Should be 16V AC) direct from the transformer as far as I can tell from the schematics. So I unplugged the transformer completely from the rest of the game and tested ALL the outputs and every single one checks out fine except for 2. The two outputs for the sound board are supposed to be 18V AC and measure at 13V AC. Sound seems perfectly fine in test mode etc., but I wanted to point it out.

The 16 volts for the flash lamp circuit is closer to 17V AC at the transformer plug.

So what would cause this drop to the J102 connector at the driver board?

P.S. I did replace BR4, C11, and checked the fuse for correct rating. I think I replaced it anyway, but it's spec at this point

No one here has any suggestions? I thought you guys were better than that! LOL.

Seriously, what could be missing here, hoping it's something obvious. LMK
Thanks

Thanks for some input here, always helps to hear another perspective.

I checked my original post, I can see it really wasn't clear. Since I realized the voltage was low at the Driver board connector, I went back to the transformer and unplugged EVERYTHING from it and tested voltages straight from the transformer itself.
ALL voltages check just fine including the 20V AC that supplies the flashers, yet the voltage is low at the connector. I'll check the connector next tomorrow.

The weird thing is the voltages for the sound board are supposed to be 18V AC and at the transformer they're showing 13V AC. But sound seems to be fine.

CPU voltages seem OK at the board and the board has never had an issue booting either. Game appears to run fine so far. So it's just the missing voltage for the flashers that I'm trying to hunt down..

Of course having had the connectors apart at the transformer, I have reseated the connector several times now, and inspected for bad or tarnished pins. All look to be in decent shape, no obvious issues here.

Ill report back after checking from the T/F back to the board, but I'm still open to ideas. Seems the only thing is that it's possible the loss is at the connector itself at J102 on the driver, and I'm guessing it's probably not it. At least not to the tune of 13 Volts!

Thanks to RonkZ650 for pointing out that the coin door switch is also part of this circuit. I have been taking AC measurements with the coin door closed and getting the low voltage reading at the J102 connector at the driver, and the correct 20VAC at the transformer plug with everything disconnected. However, what I failed to notice was that the white/red striped wires were not BOTH connected to the coin door switch until I started checking today.

I don't know how or why but one of the two white/red striped wires was connected to the START button switch lug. The entire cabinet harness and wiring was removed for cleaning while I restored the cabinet and decals recently, but this wire did not come disconnected while I was working on it, so I'm guessing this was a fault that someone else caused at some point. Why that would have been done is beyond me.

So connecting the white/red striped wire to the other lug on the coin door switch has restored the correct voltage to the Driver board, and of course, all the flash lamps now work correctly.

It really was something simple, but I just needed someone else to point out something I wasn't considering. Thanks again RonkZ650!
Putting this one to bed.