Asteroids

Typical Asteroids machines have metal control panels which have rusted through and been scratched up, mostly I'd guess from peoples wrist watch latches resting against the metal paint screened control panels. Replica overlays are available from several sources, so ask around the net. Strip the control panel, repaint it, and apply the overlay. Add new buttons to make it really look brand new.

Asteroids games also typically have a dot in the center of the screen. There's not much you can do about this. The spot killer actually doesn't shut off exactly when you shut the game off. Also, all vectors are drawn from the center of the picture. I've seen it where the spot killer does not turn the beam off and on fast enough, so a white dot appears in the center and eventually burns the phospher away. These monitors are actually fairly reliable, and to get them running again usually only takes resoldering the header pins on the PCB, and replacing the deflection transistors.

Links

Asteroids Repair Encyclopedia

Symptom: Top part of testmode crunched and scribble (not deflection problem).
There are two large chips near the XY output. These are suspect.

Symptom: No thump sound
Check the output of the transistor near the 555 timer. Check the output of the 555 timer. If output to transistor seems good (around 1.5V), replace 555 timer.

Symptom: Game plays faster than normal
Check C4 (NMI timer). It is likely that the clock input is being held high. Check to see pin 5 is not connected to ground.


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