Been restoring a Xenon machine. Here's all that I've done so far:
Rebuilt -54 board along with new male & female connectors and pins.
Replaced all the ceremic caps and diodes on the playfield switches (most were cut)
Replaces some bad / locked on coils
Brand new Alltek MPU board
Brand new Rottendog solenoid driver board
Brand new Rottendog LED displays

Game boots up fine and starts out playing good. Maybe 5 minutes into my first game, the unit lets a quick, sizzle type sound out of the speakers and basically powers itself down. Reboot and it's good to go for a while then does the same thing again.

I've read about similar items happening due to bad caps on the sound board(s). Is this my next logical step in troubleshooting it? Disconnect the sound board and see if the same thing happens?

Machine totally shuts down....lights, flippers, bumpers, coils. etc. Goes through a reset and powers itself back on. I usually turn it off as soon as it happens.

Unplugged sound board (2-pin black and red line) and tested it that way. Same result.

With power fully turned on, the rectifier board reads as follows:
TP2 = 229V DC
TP3 = 14.9V DC
TP4 = 6.2V AC
TP5 = 44.2V DC

Just powering the unit up and not playing a game, it stays on forever. I did notice that pop bumper #7 (top left) only works in test mode. Also, rollover #1 (top) will also cause drop target #1 to go down.

Rebuild sound board and that cleared up my hum while in attract mode.

I'm looking at the playfield wiring right now along with the connectors going to the boards.