Stern Tron won't start game so I go into switch edges test and HALF of the playfield switches don't register. Also have a tech alert that the motor can't go up or down but that's because those switches are some of the ones not working! I checked all the wires and everything looks good. I have zero experience troubleshooting a Stern SAM switch issue. Should I contact Stern to replace the MPU or is this likely a simple transistor repair? I thinks it's more than a single diode or transistor failure because over 20 switches aren't registering.

Ok, for what should I be looking or testing? I've been repairing games for 15 years, just never had any Stern SAM issues.

I want to report that the fix was that I accidentally switched the pictured connectors. For reference: J2 (orange wires) and J6 (white wires) for anyone that runs in to this in the future. Pictured here is the CORRECT way that the connectors should be. YES, you can plug them in wrong. Luckily, it doesn't seem to harm anything on the boards.

IMG_6071 (resized).JPG

I really can't believe that stern keyed these two connectors exactly the same, right next to each other.

I'm posting a photo of what switches don't work in case someone else ever runs in to this problem. All switches under J6, all the way down, will not work if you accidentally switch the above orange and white connectors:

IMG_6068 (resized).JPG

That's great. I KNOW this is probably isolated to those that have had to remove the head on a SAM game and plugged the connectors back wrong for some reason.