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Old 12-07-2011, 09:27 PM
DaveWM DaveWM is offline
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Join Date: Feb 2009
Location: Orlando FL
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with that briight a red raster I think your CRT is prob fine. You should go thru the setup procedure, serv switch to serv, CRT bias fully CCW, no signal to set, turn up the G2's one at a time until you just see a horz line, turn up each color until you just see each, all about the same. Return the serv switch to normal. if any one color fails to produce a line, then slowly turn up the crt bias until that line is produced with the G2 at the max, then adj the other colors down until they are all the same, just visable lines.

If you dont have enough brightness, suspect the video out tube. If its weak it causes the cathode of the CRT to be to high, thus cutting off the tube. A quick check of the CRT pins voltages will confirm this (the cathodes and the G1).

Lack of contrast is prob due to an open bypass cap (large value 50-100uf) on the video out tube cathode, follow the contrast pot lead it should connect to it, prob a section of a multisection can cap.

Lack of focus is prob a focus rectifier (tube or Se stick), but the seeming lack of focus may just be the lack of gain from the video out tube (that 50-100uf cap above). Try bridging a new cap over that and see if the contrast and focus improves. If the contrast control is doing very little then its most likely that cap.

with that much red the prob is def not the CRT.

Last edited by DaveWM; 12-07-2011 at 09:39 PM.
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