Sound of dud zener or 7824 regulator

[george a]

Hi All

I'm trying to track down a strange noise comning through my Hafler Dh-200 amp.
I've regulated the PS to the front end and now an intermittent "buzzing" noise is appearing on one channel only (with inputs shorted also)
Can any body describe what a dud zener or even what a dodgy regulator may sound like.
The sound occasionally is "started" by switching on other equipment whilst amp is powered up..
any help greatly appreciated.
Cheers

 

[Leolabs]

It looks like problem with filtering or grounding to me.But is all voltage reading normal??????Is your "buzzing" sounds like low frequency generator??????

 

[george a]

Hi
No is not low frequency at all , no hum , just a sharp buzz (not very loud) probably sevaral hundered Hz in frequency

Cheers

 

[Leolabs]

Voltage readings?????

 

[anatech]

Hi George,
Sounds like a loose cap connection or a bad cap. Check the caps on the pcb's also. You may find that you are picking up ultrasonic oscillation in the audio band. Bad bypass caps will cause this.
-Chris