It looks like my MPU is not talking to my solenoid driver board. During self test no coils will fire (flippers work). When I ground the tab on the transistors they all fire fine. I'm sure the connectors are OK - they have all been replaced. I'm thinking the U2 on the driver board could be bad? How can I check this? Anything else to check?

Thanks

Bob

Thanks Andrew,

I was afraid I was going to have to break out the logic probe for this. Unfortunately this is on a machine I sold a while back. I was trying to help the new owner get it going again but I think he knows less than I about repairing pinball machines. Everything so far has been through e-mails. The last message I sent him was to re-seat the J4 connectors. I haven't heard back - lets hope that fixes it.

Bob

Thank goodness you were right about the connectors - he re-seated the J4 connectors and everything is fine. Glad I didn't need the logic probe. Wish I knew more about using it.

Thanks

Bob

Thanks for the link Terry. And thanks for writing it. I read it before and found it very helpful - I even bookmarked the page. But I'm still a little intimidated using it. I've only used it a couple of times, I guess what I need to do is sit down and really use it and get to know it.

Bob