Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default panasonic TV picture

I have a 27 inch Panasonic TV (pana-black tube) that is about 8-10
years old. The picture has always been good until lately. The top
portion of the screen (about 4-5 inches) begins to display a bit
brighter than the rest. The rest of the lower portion is only slightly
shaded (as compared to the top), although the shading difference is
hardly even noticeable. However, in the line that seperates the two
shadings, displayed images get scrunched. So you see a normal forehead
of a person and from the neck down everything is normal, but their
entire face is scrunched down into the line. They look funny but it is
annoying. If you give the front bottom of the casing a modest tap, the
line goes away and the top shading is the same as the rest of the tube.
However, it returns indiscriminately and its frequency is increasing.

Are these the symptoms of a major repair or tube replacement? or
something more minor that is worth fixing? With a TV this age,
replacing the tube doesn't seem wise as the cost would be better spent
on a new one. It also doesn't seem wise to take it to a shop and spend
$30 to have someone tell me it isn't worth fixing. Thus I am looking
for someone who may have already experienced this problem and knows the
scoop on my TV.

C. Frank

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dkuhajda
 
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Probably weak capacitors in the vertical deflection circuit.
If the tv looks good and does not have color bleed to the right even when
the contrast and color are turned up all the way, and the black and white
pictures actually look black and white, the tv is worth fixing.

If you take it into a reputable shop, usually under a $90 total repair.

David


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jay
 
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This is exactly what I had, since you mention tapping makes it go away
you might have a dry/cold solder joint on one of the vertical IC pins.
in My set it was an LA7838 or something similar. Just hit eag of the
pin with a soldering iron and you might be good to go, one additional
test is to plug the set in and while running tap the heatsink that the
vertical IC is bolted to with a wooden dowel, if the picture exhibits
the behaviour you mentioned or it goes away you know it's a cold solder
joint

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