Curiosity: Darker to lighter strip 1/3 from left side of some TVs.

Apr 17, 2006 2 Replies

While displaying dark pictures or faint dark images.



The TVs with this characteristic is working and CRT is not the problem; purity is excellent and even phosphors.



For example:



AV-20020 shows this, while AV-27890 do not both are JVC and based on similar horizontal circuits except AV-27890 have active pincushion correction.



What this is caused by?



Cheers, Wizard


If you are referring to the shading characteristics of the CRT when the there is a dark grey screen, this has to do with the accuracy of the clamping and blanking circuits. The accuracy of the horizontal blanking circuit can cause this.

Many consumer TV sets have all types of small errors. This is why they cost much less than professional TV monitors.

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JANA _____

The TVs with this characteristic is working and CRT is not the problem; purity is excellent and even phosphors.

For example:

AV-20020 shows this, while AV-27890 do not both are JVC and based on similar horizontal circuits except AV-27890 have active pincushion correction.

What this is caused by?

Cheers, Wizard

digital or anlog TV?

If analog, you could be seeing a ghost of the horizontal sync pulse which of off to the left of the screen. If there is a ghost (reflection) you will see this on the screen as a vertical bar.

Mark

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