Strange video glitch on Pinball Action

parism

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Hi guys,

I am wrapping up my repair of a Pinball action (a bonanza of failed Fujitsu ICs and a Yamaha audio CPU that I am planing to document in a log) and the only thing left is a very weird video issue.

The game works 100% except on the high score display screen (in attract mode), there is an area of fading bluish-green color, see photo. The color extends beyond the game's screen boundaries and the text has a slight pinkish hue. In all other screens the colors are spot on.

It does this either on an RGB monitor or via a CGA-VGA adapter to an LCD. Another Pinball Action I have does not do this.

The ICs (I can't remember which ones now) that handle the RGB are tested fine.

Any ideas? I can try a narrow it down using my other Pinbal Action PCB to either the video or CPU board but was wondering if anyone has an idea further than that.

Thanks!

paris
 

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When you changed those chips out did you use the correct series such as old part was 7404 and replaced with a 7404 looks like a ic timing issue or a broken trace/pad

is that the only fault it does
 
Thanks, I used the same series ICs and last night I narrowed it down to the video board by using a known working PCB. I believe I have also identified two 157s that seem to be involved in the color palette and appear to trigger the video issue I see. More details to come once I have tested those off circuit...

This is the only fault the PCB has. Thanks for any help...
 
Yeah, I had to deal with the watchdog circuit that needed an HC ic and would not stop barking if I used an LS equivalent...
 
Interesting part is i fixed a double dragon pcb awhile back cant remember what part in the clock section anyway it had a LS fitted from factory but was silk screened a HC for a test i socket and fitted a standard LS to it and didnt work correcttly but fitting a HC series solved my issues
 
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