Quest 2, shh.. voice problem

[Mr_tuner]

Hey

Speakers make small shhh.. noise when there is no music. Panels are re coated couole years a go. can it be something whit transformers or capasitors? you can hear the nois in quiet room if no music. when un plug the power cablen then noise go away after couple of minutes. any ideas? Thanks

 

[Jazzman53]

That symptom is not easy to diagnose but you can possibly narrow it down a bit.

If the sound drops after unplugging the AC power cord, then the problem is more likely in the panel or HV bias supply, and not the large step-up transformer, and probably not in the small isolation transformer on the bias supply board.

You can rule the panel in or out by swapping the panels (easier to use jumper wires to swap power supplies feeding the panels). If the problem follows the panel, then you have a leak path somewhere within the panel. Otherwise, it's likely in the HV bias supply circuitry.

If the problem is in the HV bias supply, it's likely a leak path-- a cold solder joint would more likely produce popping rather than a soft hiss, but it could be a leaky capacitor or diode, or even something simple like dust/contamination on the underside the board, in which case a simple alcohol wipe might resolve.

Sometimes gently pressing areas on the board with an insulated probe, while it's energized, will help pinpoint a problem area.

My guess is you have a leak path on the panel but it's just a hunch.

Good luck with that!

 

[Jazzman53]

Dust building in the panel fits the symptom-- have you tried vacuuming the panel?