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Old 28th Dec 2017, 3:09 am   #7
Maarten
Dekatron
 
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,184
Default Re: iMac G3 CRT display problem

The red flare is actually clipping from the red video amplifier, not some phenomenon that is directly caused by the tube, even though it can be sign of a weak tube.

The most likely causes are either that a supply voltage to the video amplifiers is sagging (bad capacitor), the AKB feedback is bad or the red gun has gone low emission. In monitors, it can also be a coupling electrolytic in the video path itself.
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