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From: jeh@cmkrnl.uucp
Newsgroups: sci.electronics
Subject: Re: Sony TV Hi-Pitch squeal
Message-ID: <1991Jun7.030706.85@cmkrnl.uucp>
Date: 7 Jun 91 10:07:06 GMT
References: <6298@ns-mx.uiowa.edu> <1991Jun3.150425.4892@news.larc.nasa.gov> <1991Jun3.163755.825@hubcap.clemson.edu>
Distribution: usa
Organization: Kernel Mode Consulting, San Diego CA
Lines: 44

In article <1991Jun3.163755.825@hubcap.clemson.edu>, 
falcon@hubcap.clemson.edu (james lysaght) writes:
> I researched the problem (i'm an Electrical Engineer).  My TV is solid state 
> so I only researched solid state and will only comment on those.   Every 
> solid state TV has a little transistor (little as in microchips) which 
> serves to prevent this squal.  

Rubbish.  

> The squal occurrs when, over time, the transistor burns 
> out and no longer functions.  

Rubbish.  

> remedy...  buy a new TV.  It is cheeper to replace than fix (usually).

You might actually be correct here, unless the set is very expensive.

horizontal-sweep squeal (note spelling) can be very difficult and expensive to
track down and fix... particularly since many technicians can't hear it!
rec.video has had several accounts from people who reported that their tv is
making a high-pitched whine, but techs could find nothing wrong.  (A tv tech's
high-frequency hearing deficiency is likely due at least partly to working
around tv sets day in and day out!) 

The source may be the flyback transformer, the deflection yoke, or even a 
printed circuit board (not necessarily components on the board, but the board 
itself).  Someone else mentioned capacitors.  

Once you find the offending part, then what?  If it's something like a
capacitor or a PC board, you may be able to tie it down or wedge it or
something so that it can't vibrate.  If it's the flyback or deflection yoke,
replace it.  Some people have suggested potting these components, but this is
not a good idea; they would run very hot afterward and so have a vastly
shortened life, meaning that you'll end up doing the replacement anyway.  

Oh, and it's the horizontal sweep, not the vertical.  The vertical is at
60 Hz (well, 59.93) and in no way could be considered "high pitched".  But 
it too is audible in many sets, as a low-pitched buzz.  

	--- Jamie Hanrahan, Kernel Mode Consulting, San Diego CA
Chair, VMS Internals Working Group, U.S. DECUS VAX Systems SIG 
Internet:  jeh@dcs.simpact.com, hanrahan@eisner.decus.org, or jeh@crash.cts.com
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