Did you find the problem? I have the same.

On the relay board?

https://images.pinside.com/2/5c/25c2561dfd5fd3a076011de4a17384bcfcec4a3b/resized/large/25c2561dfd5fd3a076011de4a17384bcfcec4a3b.jpg

It's a Pinbot.

I finished my resto after several months. Put the playfield back in, flip the switch, all good (attract mode) . Turn my back a few minutes and come back. NO more GI on the playfield (both sides) but working on the backbox.à

Any clue?

Thanks. The solder on the relay board looks good and I hear the relay clicking on test mode. It could make sense though that the relay would have failed in attract mode (where it gets activated) thus the GI failing suddenly like that while the game was on.

I'll reflow them to see.

The power supply unit looks good but will investigate more. I was instructed to test the GI wire voltage between the solid yellow and stripped yellow, solid purple and stripped purple, etc.

I have a short in my GI circuit. I found the fuse that bridge the GI L/R to be blown again. A visual inspection and a backache later did not reveal anywhere the wires touching each other. Also, because both side are OFF, I suspect they connect both together somewhere.

How do you find a short in the GI with a DMM?

Funny things, I tried bridging my blown fuse with a 44 lamp in the holder. Both sides of the playfield GI is blowing so I tried 1 side first. Well, when I bridge, both sides get lit but dimmer than a full 2smd would. The 44 lamp lights dimly as well.

Should it only light 1 side?

I tried removing 1 fuse from the working backbox GI and it indeed cuts power to a whole string. It makes me believe both of my playfield string are connected somewhere. Do I make sense or I'm just reiterating what a short is?

GRUMPY
wayout440

image (resized).jpg
image (resized).jpg

Left side bridged, both sides get lit...

image (resized).jpg
image (resized).jpg

I'm at a dead-end here, need your help guys. The fact that both GI sides lights (Purple and Yellow wires) from a single line coming from the backbox (either Purple or yellow) tells me I'm onto something here.

But what?
wayout440
GRUMPY
mbaumle

Also, what is this circuit in the GI
Pinbot schematics (resized).png

Where are the relay board in the schematics?
Relay board (resized).png

Sorry to hijacking your thread but I thought it was a good place to start and gather even more info instead of starting a new thread. It might get more traction though... I'm in a pickle here.

Update: Started a new thread here
https://pinside.com/pinball/forum/topic/pinbot-weird-gi-problem

Found my problem. All good.

There was a wire that did not belong, either from factory or a operator. Dont' ask my why it worked before...

Removed the yellow wire at the top and unsolder each hot wire for the right side GI. Hooked them back up one by one and found nothing. No more short. I think the culprit was that yellow wire.

It clearly connects both side of the GI together hot wire to hot wire.

pasted_image (resized).png