Hi everyone.

Need some help troubleshooting a Gottlieb System 1 board set. This board set was acquired a couple of years ago and was in poor condition. Looks like it had sat in a warehouse for many years. So I am trying to get it back up and running.

The power supply is in original condition and (surprisingly) it actually works OK. Only the 8v output from the power supply is low; other voltages are OK. I will rebuild the board soon but for now I want to see if I can get the CPU to boot. So, I decided to connect the CPU to the power supply and checked for 5v at C16. However as soon as I connect the CPU board, the 5v circuit drops to about 1.8v. Initially I thought this was because of a bad connector, so I used jumper wires to connect the power supply outputs to the CPU and bypassed the crappy connectors altogether. The voltage is still too low.

I was pretty confident that this was some kind of poor connection issue until I hooked my meter up to the 5v output on the power supply as I plugged the CPU board in. The moment the CPU board is connected, the 5v line drops to 1.8v. This is at the power supply output, not on the CPU board! So it's definitely not a connector or wiring issue. So for some reason, the CPU is dragging the voltage down. What should I be checking first? Is this an issue with the CPU board, or more of an issue with the power supply not being able to handle the load of the CPU?

Thanks for any help.

It did have a NiCd battery but I removed it before I started troubleshooting.

By the way, I am not testing these boards in a game. I only have the board set and a transformer panel. So the power supply is the only board plugged in.