Space Invaders Graphics

Txny Mxnrxe

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I finally got my own Space Invaders and it's mostly working with the exception of a graphics issue. The strange part is that it only affects half of the screen. I haven't done much trying to fix pcbs so I hope this is an easy start. I put a video up on YouTube that sort of shows what's happening.

 
Hard to tell exactly what the deal is. Could be a monitor issue, also possible that the power supply is in rough shape (dried out capacitors). It it strange that the noise is only on that part of the pix.

Maybe disconnect the edge connector from the board and see if the monitor still has the noise on screen. You may need to crank up the screen brightness to see a raster on the screen.
 
I was told the monitor chassis and power supply have recently been capped. I haven't tested power or anything yet. What is strange is that the game plays just fine, just looks off.
 
Did you do a ram test? Pull.all the game chips and boot up the game. You should see a bunch of bars, hit the slam switch in the coin door, if any of the bars flash or glitch out a ram chip is borked.

Lemme see if I can pull up the midway test docs
 
I just burned the test rom and everything seems to check out. After playing around with it a bit more, I'm thinking this is a monitor issue. There seems to be a kind of pulse in the monitor which gets worse as the brightness goes up and when it is bright enough to show on the backdrop then the graphics become corrupted.
 
maybe it was a bad cap kit? I'd double check the voltages going to the game board and monitor before and after you crank the brightness see if there's anything up
 
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