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John F Miller
 
Posts: n/a
Default Sony TV - Picture Problem

Hello,

I have a Sony Trinitron KV27S22 (December 1997). A couple of days ago, it
developed a picture problem. Rather than try to describe it, I have placed
the following photos on the web:

Image of color bars: Behaving OK -
http://www.enosoft.net/kv27s22/Bars%20-%20OK.JPG
Image of color bars: Exhibiting problem -
http://www.enosoft.net/kv27s22/Bars%20-%20Problem.JPG

The problem will set in anything from a few seconds to a few minutes after
cold-starting the set. The problem will persist for a few seconds before
the display completely disappears. Only a cold reset will restore the
image. Audio is fine.

I have done some troubleshooting and have narrowed the problem to what I
think is a capacitance issue. Using a painter's stick (wooden!), I tapped
the various components on the main board and found that the tapping could
induce the problem. However, if I hold the ground of the audio connectors,
the tapping does not create the problem. When the problem is present,
grabbing the ground of the audio connector clears the problem.

The most sensitive part of the board is shown at:

http://www.enosoft.net/kv27s22/Main%20Board%20(Part).JPG

I have a copy of the Sony service manual for this set but, before I merrily
begin replacing all the capacitors, I would like to know if anyone knows a
specific cause and/or that I am barking up the right tree.

Many thanks in advance,

John Miller.