Electronics > Repair

Tek 2754P display jitter and distortion

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russan:
I am trying to repair a mostly-functional Tek 2754P spectrum analyzer. The letters and traces on the screen are distorted and jittery, and the whole image is compressed into the middle 50% of the screen in both dimensions.

Going through the service manual, it appears that the only problem I can find is the 300V supply is very low: about 180-260V, and getting worse by the minute. I traced out the 300V power supply itself and measured all the components (diodes, caps, resistors) to be close enough to correct without pulling them out of circuit. The only other card I can find that uses 300V is the Z-axis card, and I don't see or measure anything obviously wrong with it. I don't see any way to tune the 300V rail voltage.

Maybe the CRT is going bad? Charge pump capacitors are starting to fail? Looking for ideas. Thanks.

m k:
My guess is that charge pump capacitors are weak.

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