Asteroids displaying on left half of screen....

williams00

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So I have finally got some time to start repair on some of my games and Asteroids was first up.
The machine as I got it played almost blind, it did display a boomerang shaped object in the lower left hand corner. I tested a known working PCB and A/R in the cab and got a correct disply, but only in the left left corner. I recapped the PCB, the A/R and both monitor boards (G05-802). Now my boards work and the display is on the left half of the screen, not just lower left.
I have seen this issue reported in one of the trouble shooting guides when I was searching through them, but now I can't find it again. I have an good repair guide, but I do remember seeing this specific issue in one of them. Where can I go from here??

Thanks,
Aaron
 
Don't have the schematics in front of me to give you exact data, but I do remember that in the deflection section the x amplifier circuit uses positive voltage to fill the right half of the screen and negative voltage to fill the left. The Y amplifier uses + voltage to fill the top half and - voltage to fill the bottom. It is clear that the positive X is out but the negative X and +-Y is working. Before with just the bottom corner working it would mean the +X and +y circuits were not working. Look at the schematic and test for shorts and the correct voltages on the transistors that power +X circuit. Start with the chassis frame mounted transistors.
 
Ancient thread but still doin' it's job. Had the exact same issue and sure enough, one of the p700 joints was cold. Re-flowed and all is good.
 

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