I have a client with a Stern monopoly. It resest only during free money mode when you hit the bank switch entering the ramp. You can hit the switch in any other mode and it is fine. When it resets it locks on the controlled lamps until fuse F22 blows.
I tested thepu and driver board in my TSPP and it never reset. It has a new updated game ROM and still does the same thing. I replaced the connectors on the mpu and drover board around the heat sink with no change. I was thinking the diode might be bad o. The bank switch and have not replaced it yet, bit it's odd it only happens during 1 mode.
Any thoughts?