High pitch whine from flyback xformer
 

Hello;

After rebuilding the SMPS inside my 32" Zenith Z32X31D the other day
(lightning killed it); The past couple of days I been noticing a very
loud ear-piercing high pitch whine coming from the flyback transformer
and when I apply a small amount of pressure to the side of the flyback
transformer (using a insulated screwdriver) it stops making the noise,
then when I let go it starts back up again. So it seems when pressure
is applied to it; it will shutup. I think heat the expansion of the
ferrite core; triggers it maybe?

I sometimes hear this distinct sound when I am in stores around the TV
section. I noticed it ALWAYS made this noise since the day I bought it,
usually when the TV is first turned on for a few minutes, then it would
stop. But it's louder now than ever. Should I replace the capacitors in
the H.O.T. section also? Thanks for any feedback

High pitch whine from flyback xformer
 

It's not usually the flyback, but you MAY have to unsolder it, & press
it
down firmly to the pcb while soldering it, or hot glue the ferrite bar
on it.
You have to remove the flyback, SMPS, & pincushion transformers, &
coils, & coat them with hot glue. It may be misleading to find out
which
one is causing it, as touching the board, in different locations may
lead you
to find the wrong part causing it. Carefully, with the set running...if
you are
a Tech, use an insulated, plastic, or wooden stick, & gently touch each
coil, & transformer, just enough to stop the high pitch ringing. Dani.



wrote:
Hello;

After rebuilding the SMPS inside my 32" Zenith Z32X31D the other day
(lightning killed it); The past couple of days I been noticing a very
loud ear-piercing high pitch whine coming from the flyback transformer
and when I apply a small amount of pressure to the side of the flyback
transformer (using a insulated screwdriver) it stops making the noise,
then when I let go it starts back up again. So it seems when pressure
is applied to it; it will shutup. I think heat the expansion of the
ferrite core; triggers it maybe?

I sometimes hear this distinct sound when I am in stores around the TV
section. I noticed it ALWAYS made this noise since the day I bought it,
usually when the TV is first turned on for a few minutes, then it would
stop. But it's louder now than ever. Should I replace the capacitors in
the H.O.T. section also? Thanks for any feedback

High pitch whine from flyback xformer
 

If you are going to remove the LOPT, while it is out run a bit of crazy glue
around the ferrite cores, from the top and bottom. Also a moderate
application or RTV wil tend to quiet these resonations. In the old days, a
wooden shim, be it a toothpick, etc would be run down the edge of the cores
with just enough pressure to stop them from vibrating.
"Dani" wrote in message
ups.com...
It's not usually the flyback, but you MAY have to unsolder it, & press
it
down firmly to the pcb while soldering it, or hot glue the ferrite bar
on it.
You have to remove the flyback, SMPS, & pincushion transformers, &
coils, & coat them with hot glue. It may be misleading to find out
which
one is causing it, as touching the board, in different locations may
lead you
to find the wrong part causing it. Carefully, with the set running...if
you are
a Tech, use an insulated, plastic, or wooden stick, & gently touch each
coil, & transformer, just enough to stop the high pitch ringing. Dani.



wrote:
Hello;

After rebuilding the SMPS inside my 32" Zenith Z32X31D the other day
(lightning killed it); The past couple of days I been noticing a very
loud ear-piercing high pitch whine coming from the flyback transformer
and when I apply a small amount of pressure to the side of the flyback
transformer (using a insulated screwdriver) it stops making the noise,
then when I let go it starts back up again. So it seems when pressure
is applied to it; it will shutup. I think heat the expansion of the
ferrite core; triggers it maybe?

I sometimes hear this distinct sound when I am in stores around the TV
section. I noticed it ALWAYS made this noise since the day I bought it,
usually when the TV is first turned on for a few minutes, then it would
stop. But it's louder now than ever. Should I replace the capacitors in
the H.O.T. section also? Thanks for any feedback

High pitch whine from flyback xformer
 

wrote in message
ups.com...
Hello;

After rebuilding the SMPS inside my 32" Zenith Z32X31D the other day
(lightning killed it); The past couple of days I been noticing a very
loud ear-piercing high pitch whine coming from the flyback transformer
and when I apply a small amount of pressure to the side of the flyback
transformer (using a insulated screwdriver) it stops making the noise,
then when I let go it starts back up again. So it seems when pressure
is applied to it; it will shutup. I think heat the expansion of the
ferrite core; triggers it maybe?

The intermittent flyback squeal in my Sony WEGA is driving me nuts, too.
Just haven't gotten around to opening it up -- banging on the front bottom
of the case kills the noise for a while (when the set's being nice).
Sometimes these damned epoxy-encased IFBT's start singing when the potting
cracks internally (where u naturally cannot get at in order to effect
repair). Many times you can indeed resolve the squeal with nothing but glue
and/or solder in the right places, but sometimes there's no choice but to
replace the flyback.

A useful tool I 'made' for isolating mechanical intermittents is sort of a
mini rubber mallet -- it's an audio cassette pinch roller pressed on the end
of a not-too-rigid nylon coil alignment driver. Simple (and cheap) but
effective. Gently tapping suspect components with this often zeroes in on
the source. As others have said, this is potentially misleading if you
have, for example, bad solder joints on or in close proximity to the device
being struck. But this tool seems to work pretty well in many cases.