WG D9200 - Squealing sound when playing low-res 15khz games

[MonkeyJug]

I've had this monitor in my cab for the last 3 years. It's been running perfectly until recently and it now emits a high-pitched squeal, but ONLY when I play low-res games that run at 15khz.

Mid-res (25khz) and high-res (31khz) games run perfectly fine, with no squeal.  The sound is so loud and distracting, that I am refusing to play on my cab as it is unbearable!

I tried reseating the neck-board, and pushing on the fly-back, but this hasn't helped.




I'm sure this bit is important - when I first turn it on and try to play a low-res game, it is fine, but after about 5 minutes, the squeal starts.  If I turn the cab off and allow it to cool down, and turn it back on again, I can play for another few minutes before the squeal starts...


Anybody know what causes this?  I am aware that there is a certain amount of squeal that is naturally emitted from a CRT, but this is really unbearable and very recent...

TIA

[Rigby]

It's the flyback transformer.  You can replace it and hope the new one will be quieter, or you can live with the noise.  15khz is within the range of human hearing so if there are any loose coils in that transformer at all you're going to hear a squeal as the wire vibrates.

[MonMotha]

Is this a constant pitch 15kHz whine?  If so, yes, it's probably the flyback.  The core may have come loose in the housing.  Sometimes you can drizzle glue all over it and try to get it to be quiet.

If it's a "squirrley" whine that dances all over the place in pitch, it may be the power supply.  At some power levels, they seem to have an unstable control loop and make all sorts of noise.  Fun fact, the power supply is ALSO a flyback (but don't confuse them) and so has a similarish transformer that can also whine.  If this is the cause, it'll typically be sensitive to average image brightness, since that is a major factor of how much power is coming out of the thing.