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Need help with my SONY KV-27V22 TV please (burning smell after turned off and TV now dead)

Hello,

I turned the TV off at night and tried to go to sleep. Everything was
working perfectly with the TV and it had been working perfectly that
way since I bought it (9 years ago!). There was no malfunction
indication of any kind (bad picture, bad sound, smell, etc.) before I
turned it off. After I turned it off for no more than 5 minutes, I
heard a loud sound like something bursted (sounded like "pak!") and
there was burning smell coming out too. I believe there was a flashing
light coming out too -- but not sure because my eyes were closed and
the loud sound may have caused the brain to imagine the flashing light.
It was late at night and I figured it must be a blown capacitor or
resistor. In the morning, just by curiosity, I tried to turn it on with
the remote controller and it didn't turn on. No sound, picture, red
indicator light, or relay clicking or anything. I tried to push the ON
switch on the unit directly and there was nothing -- complete quiet.
Obviously there was no power feeding anything. I made sure by
unplugging and plugging in. While plugging in, I observed a small spark
at the outlet too (just like when you plug something in and you
occasionally see a small spark). Looks like there was still power
circulating on some part of the circuit.

I opened the back cover, removed the circuit boards, and tried to find
a blown component. I tried for a few hous but to my surprise, all
circuit elements appear to be 100% inact! The only fuse in there is
also not blown. There was no indication of what may have bursted at
all. Everything looked clean or evenly covered with a thin layer of
dust. The picture tube and the copper coil looked ok -- no burn,
broken, or anything. Do you think it's the flyback transformer? From my
understanding, it generates most of the other voltages used in the
unit. Or anything else I should be looking at? I'm still wondering
where the burning smell came from. Thank you!
 
J

James Sweet

Hello,

I turned the TV off at night and tried to go to sleep. Everything was
working perfectly with the TV and it had been working perfectly that
way since I bought it (9 years ago!). There was no malfunction
indication of any kind (bad picture, bad sound, smell, etc.) before I
turned it off. After I turned it off for no more than 5 minutes, I
heard a loud sound like something bursted (sounded like "pak!") and
there was burning smell coming out too. I believe there was a flashing
light coming out too -- but not sure because my eyes were closed and
the loud sound may have caused the brain to imagine the flashing light.
It was late at night and I figured it must be a blown capacitor or
resistor. In the morning, just by curiosity, I tried to turn it on with
the remote controller and it didn't turn on. No sound, picture, red
indicator light, or relay clicking or anything. I tried to push the ON
switch on the unit directly and there was nothing -- complete quiet.
Obviously there was no power feeding anything. I made sure by
unplugging and plugging in. While plugging in, I observed a small spark
at the outlet too (just like when you plug something in and you
occasionally see a small spark). Looks like there was still power
circulating on some part of the circuit.

I opened the back cover, removed the circuit boards, and tried to find
a blown component. I tried for a few hous but to my surprise, all
circuit elements appear to be 100% inact! The only fuse in there is
also not blown. There was no indication of what may have bursted at
all. Everything looked clean or evenly covered with a thin layer of
dust. The picture tube and the copper coil looked ok -- no burn,
broken, or anything. Do you think it's the flyback transformer? From my
understanding, it generates most of the other voltages used in the
unit. Or anything else I should be looking at? I'm still wondering
where the burning smell came from. Thank you!


I'd guess a capacitor in the power supply section. It will certainly not
be the yoke or flyback, those are not powered up with the set off. Trace
out the standby PSU circuit, it shouldn't take long to find the bad
part. Check all the semiconductors in that path, one or more may be shorted.
 
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