First, make sure it is not coming from the loudspeaker itself. If it is,
then we are looking at an unusual electronic interference problem rather
than simply mechanical vibration.
|NotTaR of Television Sets : High pitched whine or squeal from TV wit..
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| Reducing/eliminating yoke.. >>
If it is a new set and think the sounds will drive you insane, returning it
for a refund or replacement may be best alternative. However, you may get
used to it in time. I don't know about returning a set to a store that
doesn't take refunds (I won't even ask about that!).
In most cases, this sound, while annoying, does not indicate an impending
failure (at least not to the set - perhaps to your mental health) or signify
anything about the expected reliability of the set though this is not always
the case. Intermittent or poor connections in the deflection or power supply
subsystems can also result in similar sounds. However, it is more likely that
some part is just vibrating in response to a high frequency electric current.
There are several parts inside the TV that can potentially make this noise.
These include the horizontal flyback transformer, deflection yoke, other
transformers, even ferrite beads in the horizontal deflection circuits. In
addition, transformers or chokes in the switching power supply if this is
distinct from the horizontal deflection circuitry. Or even a portion of the
sheetmetal used for shielding if in close proximity to a magnetic component.
You have several options before resorting to a 12 pound hammer:
- As much as you would like to dunk the TV in sound deadening insulation,
this should be avoided as it will interfere with with proper cooling.
However, the interior of the entertainment center cabinet can be lined with
a non-flammable sound absorbing material, perhaps acoustic ceiling tiles.
Hopefully, not a lot of sound energy is coming from the front of the set.
- Move the TV out of a corner if that is where it is located - the corner
will focus sound energy into the room.
- Anything soft like carpeting, drapes, etc. will do a good job of absorbing
sound energy in this band. Here is your justification for purchasing those
antique Persian rugs you always wanted :-).
If you are desperate and want to check the inside of the set:
- Using appropriate safety precautions, you can try prodding the various
suspect parts (flyback, deflection yoke, other transformers), even lowly
ferrite beads, with an insulated tool such as a dry wooden stick. Listen
through a cardboard tube to try to localizing the source. If the sounds
changes, you know what part to go after.
- Once you have located the guilty party, some careful repositioning, a
strategically wedged wooden toothpick, or a dab of RTV silicone or hot-melt
glue may keep it quiet. Where the yoke is the guilty party, see the
section: Reducing/eliminating yoke noise.
- It is possible to coat the flyback transformer, but this is used mostly
when there a loose core or windings and you are getting not only the
15,735 Hz horizontal (NTSC) but also various subharmonics of this. This is
probably acceptable but may increase the temperature of the flyback.
- A replacement flyback (or whatever part) may cure the problem unless it is a
design flaw or manufacturing quality problem. However, the replacement part
could be noisier. You really do not want to replace the yoke (aside from the
cost) as convergence and other service adjustments would need to be
performed. Other transformers can be replaced.
Note that the deflection frequency - just over 15 kHz for NTSC and PAL - is
on the border of audible for adults but will likely be loud to younger people
possibly to the point of being terribly annoying - or worse. If you are
over 40 (men more so than women), you may not be able to hear the fundamental
at all (at least you can look forward to silence in the future!). So, even
sending the TV back for repair may be hopeless if the technician cannot
hear what you are complaining about!
BTW, if you have a really old tube type TV, the power tubes (damper and
horizontal output) can also whine but these sets are few and far between
these days :-).
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