Question about Standard (CRT) Televisions

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RCA CRT TV thin white horizontal lines

I suspect this is a standard malady for CRTs but here are the specifics of the set:

RCA 31" Home Theatre F31700GG chassis #CTC169JS5.

The thin white horizontal lines (slightly sloped) are across the entire picture and are spaced about 1 inch apart with some compression of spacing towards the top of the screen and expansion of spacing as towards the bottom of the screen (I suspect vertical scan related). The desired image is barely visible with a pinkish-grey cast. When I adjust the Screen potentiometer the TV shuts down.

I can replicate the lines on two other sets, a similar year model GE 27" and a really old RCA 19", by adjusting the Screen potentiometers.

I have all the schematics for the 31", a 275 MHz oscilloscope with built-in time interval multimeter, and two analog VOMs. Unfortunately I don't have a high voltage probe, power supply, or frequency generator.

Thank you,
Floydage

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  • sgunupuru May 18, 2008

    My 32 inch Gemstar TV was working all fine till I disconnected the cable and reconnected back. Thogh all the connections are exactly same I see white thin horizontal lines. This has nothing to do with my VCR, DVD player or my cable connection since the TV gets disolays these lines even when it is disconnected from all these.



    I have no clue what happened...

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Look for bad capacitors in the vertical deflection amp, and in the pin amp sections. This is common on most of these types of TV sets.

The caps tend to go high in ESR with age. It is best to use an ESR meter to find the bad caps. It will be a lot faster than workign out waveforms with a scope.

Wikipedia explanation about capacitor ESR:
http://en.wikipedia.org/wiki/Equivalent_series_resistance



Jerry G.

Posted on Apr 24, 2008

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Great info you've provided.
Check this link to get more info about those retrace lines.
Let me know if you required further assistance.

Posted on Apr 23, 2008

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