Help troubleshooting ms pac-man. Ram issue?

[jcroach]

Hey! I’m new to troubleshooting my games. This ms. Pac-man was working fine when I bought it. Replaced the 4u to bring back the original mazes. Replaced the 6e to allow for attract mode during free play. Replaced the 6f to bring back to the original speed. Everything worked great for a week. Replaced the joystick this weekend. Worked fine for a while. Then started freezing randomly after a couple minutes. Now it won’t boot. I’m getting this screen.

Quick internet research suggests it might be a ram issue or a bad edge connector. How do you recommend I troubleshoot this? How is the best to clean and reseat the ram? I’m wondering if it might be a bad ram. Maybe 4l. Suggestions?

[CheffoJeffo]

Been a while since I looked at one.

Voltages OK? Original PS or switching replacement? The onboard regulator might be futzed.

IIRC, Ms Pac has a test mode that includes a RAM test, but damned if I remember how to access it.

I use a pencil eraser on edge connectors and chip legs to start and move up to something more abrasive if required. I like to have spare chips on hand because I'm clumsy and sometimes break a leg.