NotTaR of Television Sets : Blank picture, good channel tuning and s..  
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Blank picture, good channel tuning and sound

Since the tuner and sound are ok, horizontal deflection which usually generates power for most of the set is also working.

Does 'blank picture' means a totally black screen with the brightness and contrast controls having no effect whatsoever? Or, is there is no picture but there is a raster - scan lines on the screen? The direction in which troubleshooting should proceed differ significantly depending the answer.

Here are some questions:

  1. As above, is there any light on the screen at any settings of the brightness and contrast controls, and/or when switching channels? Can you see any raster scanning lines?

  2. Can you hear the high pitched (15735 Hz) of the horizontal deflection?

  3. Looking in the back of the set, can you see the glow of the CRT filament?

  4. Do you get that static on the front of the tube that would indicate that there is high voltage? Any cracking or other normal or abnormal sounds or smells?

Possible causes of no raster:

Possible causes of no video (but a good raster): Problem in video IF, video amplifiers, video output, cutoff due to other fault.

It could be as simple as a bad connection - try gently prodding the boards with an insulated stick while watching the screen. Check for loose connectors and reseat all internal connectors.

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