I picked up a non-working Memory Lane and am trying to get it up and running, but have run into a road block.
I started at the rectifier board. All fuses are correct values and buzz continuity. Then I plugged in J2 and turned the game on, and tested all five test points for proper voltage - they all checked out properly.
Next I turned the game off, plugged in J1 and J3 to the rectifier board, and turned it back on. All I get are GI lights, and a solid red light on the original Stern MPU.
Then I take out the power driver board with the intent of recapping it and performing standard mods. While I have it out, I decide to put in a working Alltek driver board from another game, to see if that solves the issue, but I still get the solid red light on the MPU. The Alltek has green LEDS indicating the proper power, including the cyclone LEDs.
Then I tried putting in an Alltek MPU set to Memory Clear (was in another machine) which is when I get the Over Voltage light on the MPU. So it seems like the trouble is in the power the MPU is getting.
All connectors to the MPU appear to be seated properly and with keys that line up. As I'm reading the schematic, it looks like J4 provides the power from the driver board? I could repin but I figure if that was the issue it would only reduce voltage, not increase it?
I'd appreciate help with next steps in terms of troubleshooting. Thanks!