Will be either the power connector on the MPU (J4), the connector pins (in the connector housing) or the ROM sockets on the MPU. Remember - these boards are 30 years old !
OK, thanks, could it be something to do with temperature? I left the machine with just the G.I. on for a while and them pressed the reset button a few times. It booted up but the lamp on the solenoid expander board under the playfield was flashing. I did this a few more times (turned it off and on and pressed the reset button repeatedly)and each time it eventually booted up and the lamp on the solenoid expander would be flashing. Then I left it with the G.I. on for a while longer, pressed the reset button again and it booted up and everything seemed to be working OK, no flashing lamp on the expander board. After I left it in attract mode for a while longer I could turn it off and on and it would boot up normally each time without needing to press the reset button. There just seems to be issues as it warms up and then it runs fine.
Does this help to narrow down the problem at all, i.e. are any of the components listed above more likely to need to warm up?
