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toolb0x

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I have a Wells Gardner 19k4901 running '88 Games by Konami, while adjusting the vertical size the screen splits and leaves a black bar. Any idea why this would happen?
19k4901.jpg
 
Looks like a form of fold-over. Have you recapped it?
 
I only recently purchased it, the caps look newer than anything else on the board. I can't guarantee that its been recapped but it looks like it.
 
Have you tried the Vert Damp adjust on the main board. Also what are you getting for DC at the 130Volt line
 
i really hate the old modular WG boards.
check or go over all the solder joints on the connections to the vertical sub-boards before you do anything else.
the joints always get stress-cracks.

btw, where did you get it?
i have only seen them in old midway stuff like gorf and pacman - they have always been screenburned to hell!
 
I've seen this before with a k4900 yoke mismatch.

There are multiple revisions of the k4900 and they are not all interchangeable with the same yoke. It won't kill anything but you will get foldover like you are seeing.

Not sure if it's your issue but worth checking.
 
Found the yoke/chassis combination info on KLOV. I came across the same problem when. I bought a spare chassis for my Millipede, repaired it except for the foldover issue.

See if this helps:

3 versions:

"Latest" version had Vertical Dampening pot and a Vertical Position circuit board attached to the main board. (-040 confirmed below)

-040 , -055, -057

Yoke: 2021111258 or 2021111264

"Intermediate" version had a Vertical Dampening pot and NO vertical position circuit board.

-034 , -037

Yoke: 2021111258 or 2021111264

"Early" version did not have either a vertical dampening pot or a vertical position board. (Confirmed Below)

-023

Yoke: 2021111194 or 2021111201

"The early version is not compatible with either the Intermediate or latest versions due to the yoke being slightly different. If you use an early chassis on either one of the later ones, you'll get a foldover you can't adjust out as stated in the bulletin."
 
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