(Topic ID: 234618)

Tech: Gottlieb System 80 display flickering/xtra characters

By vipe155

2 years ago

Topic Stats

  • 10 posts
  • 5 Pinsiders participating
  • Latest reply 2 years ago by ChrisHibler
  • Topic is favorited by 1 Pinsider


Linked Games

#1 2 years ago

Hi everyone,

I wanted to ask a quick display issue question on a GTB System 80. I looked at the pin repair guides and wiki and didn't see anything that was quite like the issue I have.

I don't have any issues with missing segments/digits, but I have a intermittent flickering with some extra numbers displaying on my credit and P3/P4 displays. Sometimes it's fine, other times it goes crazy for a few seconds flashing extra characters on those displays.

Switches quickly between something like this:

I've cleaned the edge contacts, reflowed/checked the display boards. Is it a connector related issue possibly?

#2 2 years ago

Have you tried swapping around displays? Does the problem follow the displays or stay with the same position regardless of which display board is in that spot?

#3 2 years ago

Reminder: never remove or install a display connector with power on.

That is most likely a connector issue. Next most likely is the display drive circuitry.

Chris Hibler - CARGPB #31
http://www.PinWiki.com/ - The new place for pinball repair info

#4 2 years ago

Yeah, I know not to mess with the displays when the game is on. I haven't switched around display boards, but I can do that to see what happens. I do have an extra credit display from a MGOW I'm fixing up I could try as well.

It's more difficult to figure out when it doesn't do this all the time. The game may sit on for several minutes with no issues, then suddenly the Credit/P3/P4 displays will freak out for a few seconds. Or it might do this immediately on power on/boot.

#5 2 years ago

Connectors probably need to be repinned.

#6 2 years ago

Concur... most intermittent stuff with my displays have been connectors.

#7 2 years ago

I didn't catch that it was Credit/P3/P4 earlier.
Definitely connector pins then.
The manual/schematics will help ID the connector.

Chris Hibler - CARGPB #31
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#8 2 years ago

Another tip: investigate the 0.093" connector A12J4-P4 in the backbox.

#9 2 years ago

Thanks everyone for the help.

I was looking at the schematic yesterday, and if it's happening on multiple displays, then it's probably one of the connectors to the MPU or the A12J4/P4 connector mentioned above right?

Should I just go ahead and replace all the pins on those connectors instead of trying to trace down the specific wire(s)? Since they are all IDC, it kind of makes it less desirable to just fix specific wires on the connector.

#10 2 years ago

I would repin the whole connector.

Chris Hibler - CARGPB #31
http://www.PinWiki.com/ - The new place for pinball repair info

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