Experiencing a weird one, gang. A few weeks ago, my Harlem just wouldn't boot. Figured, I'd get to it later and just left it off. Checked it more thoroughly, today.

On the rectifier TP1 which reads 3vdc instead of 5ish.

With the sound board hooked up, the TP5 reads 66vdc and I get no 7th flash
Without it hooked up, I get 43vdc on TP5 and the game boots and plays fine, with no sound, obviously.

Can something on the sound board be causing the solenoid voltage to spike? Does my low TP1 have anything to do with it? I wouldn't think so, but not sure.

Specs of the game:
MPU is Alltek.
All other boards are originals.
All LED with Seigecraft adapters.

Any ideas?

Thanks in advance.

Someone before me has does some header replacement on the rectifier. Bridges all test fine as well. I had planned on replacing all sound board caps. Ordered them a while back, but hadn't done it yet. I started out thinking, I'll just throw the brand new rectifier I have in there, but noticed the soundboard weirdness.

Replaced the rectifier with a new one I had stashed. Also capped the soundboard prior to that. Neither step made a difference. Still won't boot with the soundboard connected. I reflowed the headers on the soundboard as well. Maybe need to repin the connector housing. Ugh.

Issue seems worse now. 66vdc with the sound board connector unplugged and over 100vdc with it plugged in. It will still boot and play without the sound board plugged in. Could the transformer be bad?

Damn. That was it. You're an indispensable resource, Ken. Guess I replaced a perfectly good rectifier. A penny diode. Gotta love it.