Can someone please explain exactly how to test system 6 power supply board voltage for the general illumination? All the GI lights are out on my BK, which has a system 6 power supply. All other game functions appear normal, including the CPU controlled lamps. When I say exactly, I mean where to put each DMM lead. BTW, I think I've eliminated most other common causes, like blown fuses, shorts, etc. Thanks in advance!

Hey Cody - thanks for your detailed post. My BK has a sys 6 power supply, which doesn't have a J8 or J9 connector, unless my brain is totally fried, which is a possibility. Can you describe testing a sys 6 supply?

Cody-thanks so much for your post-super helpful. Testing per your diagram gave a 7.5V reading on the lower lugs, but less than 1V on the upper. The 20amp power supply fuse has repeatedly tested good for continuity on my DMM. Out of curiosity, I swapped the 20A SFE fuse that was on the backbox GI string with the 20A AGC fuse that was on the power supply. Mysteriously, test lamps on both the playfield and insert board now work. Both fuses still test good using my DMM set for continuity. I'm ecstatic that maybe the GI problem is fixed, but any idea why the two fuses would act differently? Is there something unique about a SFE fuse? Thanks again!!

Grumpy-so the fuse can repeatedly open and close under load? Is there any reason it would open under load on the power supply board but not on the insert board under the same load?

It is strange. I'm going to switch them a couple more times just to see if the problem reoccurs.

Well, now when I swap the fuses back and forth, the GI lights continue to work, regardless of where I put the SFE fuse. So maybe the power supply fuse holder was just "dirty" enough that it wasn't getting good continuity.

Grumpy-yep, the fuse holders are tight.

Ha! Yes, I guess, although I've never had a "dirty" fuse or fuse holder cause that problem. After the fuses tested good, I spent a lot of time running down everything else, from the GI relay to a playfield short, you name it. Happy that the GI lamps are working now, anyway.