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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gfgray
 
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Default SONY KV-32S40 32" Trinitron screen distortion bowtie

The bottom half of my screen intermittently shrinks like a bowtie and
sometimes the picture would just disappear. Giving the TV a good
smack fixes it. Then, after the TV warms up, the problem no longer
intermittently appears.

I resoldered a bunch of connections. Now, when I turn the TV on, I
get the degauss sound and the power light blinks like it normally
does during warm up, but the picture never comes on. When I was
resoldering, I found a spot that looked like sony spilled some solder
and may have shorted two connections on the mainboard. I cleaned that
solder off. Could that have been an intentional solder connection on
this TV model?

Also, I pulled on that thick red wire that goes from this transformer
thing on the main board directly to the picture tube. I then
realized it wasn't supposed to come out of the transformer thing.
TIA


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JamesQB
 
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Default SONY KV-32S40 32

Was it a solder splash that rubbed off, or did you melt and remove the
solder across the two connections? It sounds like you may have removed
a solder link that should be in place. If the solder was making good
connection between the two areas it was bridging, then it's a simple
of case of logic: if the set was working fine like that, then it
wasn't an accidental solder splash, or something would have been
malfunctioning from day of production.

As for the lead you pulled on, that's the EHT lead that carries
several kilovolts to the CRT anode. I would avoid messing with this
lead. Did you pull it partly out of the transformer or something? If
you didn't pull it from its catches, then I doubt you've done it any
harm, but make sure you haven't partly pulled it out and that the
anode cap at the other end of the lead is still properly in place on
the CRT, but be very careful as the tube capacitance
means that there is still dangerous and painful high voltage present
sometimes even days after last having the set on!

It may be best to have an engineer look at the set if you aren't sure
what's what. There are other parts which store a good deal of voltage
for long amounts of time and can be either bloody painful or at worst
dangerous. I personally think that for someone to try repairing their
own sets, they should have at least basic knowledge such as knowing
what the flyback transformer is and does... etc. That way they can
stay a bit safer.

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RDC RDC is offline
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Default

Quote:
Originally Posted by gfgray
The bottom half of my screen intermittently shrinks like a bowtie and
sometimes the picture would just disappear. Giving the TV a good
smack fixes it. Then, after the TV warms up, the problem no longer
intermittently appears.

I resoldered a bunch of connections. Now, when I turn the TV on, I
get the degauss sound and the power light blinks like it normally
does during warm up, but the picture never comes on. When I was
resoldering, I found a spot that looked like sony spilled some solder
and may have shorted two connections on the mainboard. I cleaned that
solder off. Could that have been an intentional solder connection on
this TV model?

Also, I pulled on that thick red wire that goes from this transformer
thing on the main board directly to the picture tube. I then
realized it wasn't supposed to come out of the transformer thing.
TIA


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Those Sony sets are notorious for having bad solder joints that can kill the Power Supply and/or H.O.T. Ceck and see if the H.O.T is shorted and then resolder everything that leads up to it, driver transistor, transformer ect. Check the power supply for shorted transistors as well as as an open resistor, R607.

Pulling the Anode wire (big red wire) out of the "flyback transformer" is EXTREMELY dangerous. Even if the sets been off for awhile and is unpluged the tube still has a charge in it. You may want to leta tech handle the rest of the repairs before ya discover the shocking side of TV repair.

Last edited by RDC : March 4th 06 at 05:44 AM
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