Follow the GI wires back from the PS to the playfield.

Check for voltage at each connector block.

7/10 times it's the connection to power. Do any of the connectors look burnt or brittle?

Where along the connectors did you loose power?

You know you have it at the power supply (test there first) and don't have it at the playfield.

You should have 6.2vac at each connector all the way to the playfield.

Make sure you meter is on AC and let me know where in the chain the power has been lost.

Usually it's a solid yellow wire + a yellow wire with a white stripe.

First, meter on AC 20 volt setting

Next measure the voltage right at the power supply board.

Then follow the yellow wires along to each connector, until you find the spot where you no longer have 6.2 volts.

Check the connector that runs from the backbox to the playfield. Follow the wires from the fuse block down into the hole that leads to the bottom cabinet. There will be a connector there. Check that connector.

Is it possible that you have pinched some wires while lifting the playfield?

Did you find the problem? I have the same.

On the relay board?

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

Agreed, Firpower does not have relays on the GI. Plumonium do you have Firepower 2?

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?

Those little relay boards always have cold solder joints. Always. Reflow all the joints on the board and see if that helps.

Pinbot doesn't have an interconnect board, but I believe it's still prone to poor GI connections. They're the yellow connections in the backbox. See if they're burnt up as well.

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.

What was the solution? It may help others who find this thread in the future.

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