what the heck can cause this???

no way. all new caps and i've even swapped the chassis now and tried a different board....so its got to be the tube itself (which i doubt), voltage loop somewhere, or ???
 
bad ground to the monitor from the board? that wire is solid.

I'd check it anyway. Could be a bad ground from the game board.

Pull the signal cable off of the monitor and turn up the screen control until you get a slightly grey picture. If that raster has the same images then its the monitor, if not its coming form the game board/power supply.
 
Bad signal ground......

That's my bet. Doubt it's the tube.

BTW, the tear at the bottom of the screen is a dead give away for signal problems.
 
It may not be the cable but might be the game board. With the cable disconnected from the monitor board see if you get 3-4VDC between the ground pin and a sync wire. You should also get anywhere from a half a volt to a volt on the color pins. The color wires will vary with what info would be presented on the screen.

If the monitor was powered up without an isolation transformer on it then it would pop the ground signal on the game board.
 
Well, could be dirty +5 in the cab but its usually accompanied by a NASTY hum in the speakers.

If its a factory Atari harness I wouldn't be surprised to see the GND wire pulled out of the IDC pin on the connector on the game board. FYI, it doesnt have to be pulled all the way out just out far enough to not make a good connection to the pin. Those .156 connectors are really easy to damage, especially at this age in their life.
 
damnit you are correct Sir! there was a break in the wire, like in the middle as if it had been streched. THANK YOU VERY MUCH! would have never checked the continuity of a wire as the terminals were....well, terminated ok.
~s
 
damnit you are correct Sir! there was a break in the wire, like in the middle as if it had been streched. THANK YOU VERY MUCH! would have never checked the continuity of a wire as the terminals were....well, terminated ok.
~s

Good times!
 
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