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Methods for Reducing 15kHz CRT Whine?

Pickelhaube808

Pickelhaube808

Experienced Member
Joined
Jan 13, 2023
Messages
74
Location
San Antonio, TX
I have a few CRTs which range in severity when it comes to emitting that nice 15kHz screech- from my awesome Samsung Syncmaster 900SL which will only make an audible noise when feeding in jank signals (it is mostly quiet), to my Toshiba 14AF42 TV which makes a pretty audible and annoying noise, to my IBM 5153 which I have to use earplugs with or else I will get a headache.

Both in wanting to make it more tolerable to be around these and wanting to preserve my high frequency hearing for as long as possible, I want to try to dampen the components causing the whine to make them as quiet as possible. I have seen cases in other types of electronics where manufacturers (and end users) will use non-aggressive adhesives such as hot glue to try to dampen inductors to stop them from making noise, but is this possible with flyback transformers in CRTs? How hot do they usually get?

I have opened up and performed maintenance on various types of CRTs in the past, so I am open to pretty much any reasonable suggestions for how to try to get rid of the noise. Also note that while it came to mind, I do not want to try to put any sort of sound deadening material inside any of the CRTs as I do not want to impede airflow.

:)
 
Most likely, the whine comes from the horizontal output transformer or the horizontal deflection yoke. Those can easily be damped using glypt or other such stuff. The side benefit is that it suppresses a lot of corona discharge. The first thing to find out is what is causing the whine. A plastic hose held to the ear can help to localize the noise (the CRT cover is removed, of course).
 
Wonder if any general purpose noise cancellation devices exist that aren’t both large and expensive and could target a limited frequency?
 
If (in a darkened room) you don't see the blue glow of a corona leak around the flyback, then things have likely dried out a bit. In the old days, they'd boil the windings in beeswax; later on, stuff like Glyptal corona varnish was made available to the service people. Amazon has some.

If not a high-voltage corona leak, it's likely just a mechanical vibration.
 
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