I have a Williams System 6 Blackout that I've been having random issues with getting the MPU to boot and stay on. Occasionally when I flip it on the PF lights don't turn on in attract mode sometimes they either don't light at all and other times only a few will light like it was started to boot but then they are just stuck on not changing at all. Score/credit Displays also don't light at all. If I flip the machine back on and off quickly sometimes it starts right up an I can play games as if nothing happened.

Then sometimes it starts right up and mid game the PF controlled lights stop working. Once it blew the 5 volt circuit fuse.

It is stock no additional rectifier board just standard Williams originals also doesn't have NVRam yet. I did recap the power supply but it didn't help.

Any ideas what could be going on? Sometimes it goes weeks without and issue then all of the sudden I can't get it to turn on correctly. Only once has it blown a fuse which I replaced with same amp fuse and it worked for weeks now no issues until today I can't get it start up again.