My SBM was working fine for the last few months - then the other day the playfield lights went wonky and the speaker buzzed and the machine rebooted. It did it a few more times then just went to a solid buzz. The MPU LED goes dim and never shuts off.

Solonoid board
TP1 3.9V
tp2 204.8
tp3 spikes to 18 then settles to 4
tp4 249.8
tp5 spikes to 40 then settles to 9.88

rectifier board

tp1 spikes to ? then settles at 6.08
tp2 247v
tp3 spikes then settles at 10V
tp4 7.14v a/c
tp5 45v

Pulling the MPU the voltages don't change

I tested C23 and re soldered it - it was replaced before but the solder joints were cracked lose only held by heat shrink.

Whoever repaired this before wasn't great at soldering but it was working for a long while for me and the previous owner.

Here is a pic of the rectifier board
IMG_8505 (resized).jpg

The spiking is my tectronix multimeter/scope sensitivity at ps startup.

The problem fixed itself after reseating of all connectors and cleaning up some charred pins.

The 12 V line traverses the sound board connector. It could be that pinch was punched down sometime and damaged the wire as well. That’s just a bad bad practice and why pinch connectors in cars are a bad idea.

Oh well it’s fixed!?!?

I've decided to purchase a new board and connectors - with the damage to the board and traces for $60 I can get a new setup and not have to deal with trying to clean it all up.

Thanks for the advice and pointers - I had seen the thread by vid - but didn't follow it to the rectifier board section.