Whistling PSU

[wylton]

One of my Avondale TPX1 psu's had started to whistle. I've ignored it for a while, but this morning I decided to take a look. I had found previously, that moving it or jamming something between the chassis & the case quietened it, but it got to the point where I couldn't stop the high frequency whistle. This is mechanical noise, btw, not being transmitted through the hi-fi. So, I unplugged it & took it up to the workshop, plugged it in & it's whisper quiet. I have spare transformers & was planning to change it, if it had gone noisy, but this appears not to be the case.

In the listening room the mains comes from a dedicated supply, so I would expect it to be reasonably clean. I wonder if this is emc related? In the rack, it sits next to a linear supply for the Auralic mini. Another TPX 1 that supplies the Naim pre-fix, mounted on an adjacent rack, has no such issues. It's driving me nuts!

 

[a.palfreyman]

As you have 2, swap them over?

 

[Barrymagrec]

Whistling suggests oscillation and that suggests faulty caps. Do you have a scope?

It is quite possible this only happens under particular load conditions which you have not re-created in the workshop.

I appreciate the whistling is coming from the PSU, not the speaker, nevertheless....

 

[wylton]

As you have 2, swap them over?

Not quite so straight forward. They are both multi caps, the equivalent of two hi-caps in one box & the two multi-caps are different configurations.

Whistling suggests oscillation and that suggests faulty caps. Do you have a scope?

It is quite possible this only happens under particular load conditions which you have not re-created in the workshop.

I appreciate the whistling is coming from the PSU, not the speaker, nevertheless....

Yes, I do have a scope, the problem is that with the current set-up, the leads only just about reach, so trying to scope it will be difficult!. I have moved the Auralic psu & I'm about to attempt to plug the multi-cap back in; I'll report back later.

To make matters worse, SWMBO refuses to turn the TV down for 5 minutes while I test the supply & I have a big migraine come on!

 

[wylton]

OK, after a lie down in a dark room to get rid of the migraine, I just tried the psu & it's as quiet as a mouse, so not sure if it was just moving the Auralic psu, or tightening the feet on the TPX, but either way, glad to be rid of the whistle!

 

[a.palfreyman]

Good news. Now you just have to put the auralic psu back and see if it returns.

 

[wylton]

Good news. Now you just have to put the auralic psu back and see if it returns.

Yes, already did that, the Auralic linear psu is now at the bottom of an adjacent rack & the TPX is quiet as a mouse; looks neater too.