Hi, new here and looking for some help on a Stargate machine. It did work at one point not long ago.

Whats happening
1. Turn on and it screeches/pulses, but doesn't boot. Solid light on main sound board, no light on aux sound board, solid light on display board, and fast pulsing light (with screeching) on CPU board. Voltage on the pot on the PS board is set to 5.16v. When I turn up the pot a bit, things get better. The LED on all boards are flashing. I can turn the pot back down to 5.1 and it stays the same. When game turned off, you have to do the same thing over again.

2. Throughout this entire process, there is no display present on the DMD. its blank. I measure the voltages at A8J2
Pin 1 - 5.3v
Pin 4 - 12.24v
Pin 5 - 64 v
Pin 7 - 143V (way too high)
Pin 8 - 131 V (way too high)

Same corresponding voltages at the DMD board connector

I do get sound/music once I play with the pot.

I can upgrade to the new pot, but its seems stable with no fluxuation, so I am not sure thats' my problem.

I ready about the watchdog circuit and R5/R6, which are currently 680K.

I have reseated all connectors, ribbon cables, and checked fuses.

I get no activity, I can't seem to add credits, or get an actual game started ( not sure if that's related to not having a display)

In the past it did the screech without starting a couple times, and after cycling power it would kick in. Now it does not.

Any thoughts, help pinpointing the issue(s)would be appreciated.

Anyone?