Man...had it all typed, lost it due to timeout.
Okay, here goes again. I have had 2 of these, and worked on several others.
There are 2 cpu's on the cabinet. You should be getting self test for both. You are only receiving test for one, and its failing.
First step ***
Check your voltages from your power supply with a meter, to ensure you are getting clean accurate voltage to both cpu's. If you aren't comfortable tracing that down and testing, then yes, you are in over your head, and need a buddy, or a repair tech for help.
Once you've confirmed you have clean voltage, then re-seat all connectors on the cpu's, and check that the signal wires are leading up the monitors, and are seated correctly.
If you still cant get past the self test, or the right monitor is only getting raster with no signal to it, then its time for board repair. You can swap the two cpu's video leads around, just to make sure the right one isnt a monitor issue, but if all you get is the same dead raster when its hooked up to the other monitor, then it's definitely the board.
If it is board issue, you will probably want to talk to ElDorado, or one of the other board repair places. I have enough of a harness, and spare parts that Channelmanic *may* be able to create a test rig for it, and fix it, but that's depending on his schedule amongst other things.
BTW, the cpu's only have connections for Power, Video, Sound, Pedestal, and link to other pcb. I know it's a lot of wires, but it's not as complicated as it seems. The board in between the two cpu's is the sound amp.
Now..............lets address the pedestal.
Pedestals have 2 I/O boards, and they get power from the main cpu....so if one isnt lit (probably the right one), it means the main cpu is not giving it juice, which is highly indicitave of a cpu problem.
Those I/O boards have 4 connectors.
4pin flat connector - Pedal switch
12pin flat connector - service panel (each side of the service panel goes to its respective i/o seperately)
6pin rectangular connector - Gun
12pin rectangular connector - wire harness back to main cabinet.
The wires you have running loose, seem to be black, white, and the yellow/green earth, so i'd assume its probably coin counter stuff, but I could absolutely be wrong. Manual shows there are only the two connectors between the pedestal and the main cabinet, which you have plugged in. You need to trace the spare wires back to where they go in the pedestal, and give us that info to be certain what they are.
I hope this helps. It's a big beast of a cabinet, but its a great game. I'm sorry you got it not working, and hope you didnt pay working prices for it...but with time and patience, and maybe some board repair, you can get it up and running.