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No picture. Low EHT ?

LG ctv model CT-25Q26ET

LOPT

6174Z-6012R JBK18

Fault - Black screen, no picture or on-screen display. Sound O.K.

If I short the red, green and blue pins on the crt to ground, I get a full screen of that colour. During that time I can barely see a faint tv program picure.

Adjusting the screen control makes no difference to the brightness, but the focus control does make some differnce.

Is low EHT from the transformer the likely cause? I do not have a high voltage probe. After I turn off the ctv, I can get very little spark when I discharge the picture tube.

Other voltages from the transformer and the B+ appear to be O.K.

Can anyone suggest anything else I should check before ordering a new transformer?

Thanks, Russell Griffiths.

Reply to
rg26ce1991
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On 16 Jan 2007 22:07:09 -0800, " snipped-for-privacy@hotmail.com" put finger to keyboard and composed:

A symptom of low EHT would be a large raster. You would probably also see lower than normal G2 and focus voltages. I'd also check the other secondary voltages, eg the supply to the video amps, heater voltage, etc, but you say that you have already checked these.

You could try to make sense of the HR Diemen equivalents:

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Each variation has a schematic diagram with voltages.

- Franc Zabkar

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Reply to
Franc Zabkar

I would suspect problem around the RGB amplifier. How is voltage to to teh RGB amps? Usually 180-200V. I do not remember his model, but if it uses RGB amplifier on a chip, I would replace this chip first.

Rudolf

Reply to
Rudolf

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