Space invaders - Double Image problem - Game plays but corrupt graphics

barakawins

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Space invaders - Double Image problem - Game plays but corrupt graphics

Picked up a space invaders. Got the power supply fully working. I'm getting a double image
on the screen for some reason. Not sure what could cause this. Bad capacitor? Bad IC? Ram? Anyone know the fix for this? See photos. Game plays fine but it's doubled up.
 

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image

The image is stable and solid. Yes. I can play the game. Although.. When I fire or move, there are 3 images that move and fire. It's just all cluttered up.
 
Continues!

OK. Installed a fresh cap kit with no change. Anyone see this kind of issue?
Seems like the screen is jittery a bit but it is a triple image. Any ideas on what to look for?
 
Hmmm...if its playing ok I'd suspect monitor. Unplug the main plug off the motherboard, then turn up the brightness on the monitor and look at the blank raster. If it looks like it has simliar lines (where it may be 3 seperate rasters), then see if you can adjust it out on the monitor.

Its possible a clock/sync circuit could cause that too but usually it wouldn't play right if it did.
 
monitor

It's definitely a monitor issue. I put in a known working space invaders boardset and it
came up the same way. I tried playing with the horizontal hold and that's the best I can
get with multiple images. I tried the Horiz Lin. pot on the chassis and that doesn't do much.
Is there a special way to make adjustments to make one picture or would this be some
kind of resistor or transistor issue?
 
Tripled image

My space invaders is doing exactly the same thing. Plays but the image is tripled on the screen. Did you end up figuring it out? Thanks
 
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