the GI in the backbox goes to J3 on the power pcb above the transformer. ( the big 20 pin plug) pin 1,2 10,11 should all be familiar colors

faults on that board are very common

Some folks like to keep their pins all original, but for me, trying to repair an old, under-engineered Bally rectifier board that has probably already been hacked six ways to Sunday is just not worth the effort. Get the replacement board from Great Plains, replace/re-pin your Molex connectors, and be done with it once and for all.

https://www.greatplainselectronics.com/proddetail.asp?prod=135-105

If it shows out of stock, email Ed. He sometimes has one or two on hand.

If the general illumination lights are working on the playfield, then the rectifier board that supplies ~7 volts AC for these lamps is working correctly. That would mean there is a 99% chance that the problem is with the connector that connects the rectifier board to the molex connector that carries the voltage to the lamp sockets in the backbox. The connector I am referring to is the large 20 pin Molex connector identified as J3 on the rectifier board. If the white connector looks burnt, which is likely will, this is your problem. The solution is to remove the rectifier board from the machine and replace the J3 male connector pins. You MUST also replace the connector pins in the Molex connector. While this is not for the novice pinball repairer, it doesn't involve more than $5 in parts and will be much cheaper and easier than replacing the entire rectifier board, which involves soldering a bunch of wires (and you will still need to replace the Molex connector pins).

Hello just wanted to add that this worked for me. Mata Hari had playfield GI ON, but backbox GI OFF.

I re-pinned the three plugs going into the rectifier board. Backbox GI came right back. Thanks.