VR66 buzzing noise

[rbranco]

For anyone that has installed one of these, did you find it makes a buzzing noise all the time while ebus cable is connected, if I take it out then the noise goes away.

 

[rbranco]

Seems one of the ceramic capacitors is causing it.

 

[Harry Bloomfield]

Seems one of the ceramic capacitors is causing it.

There are no ceramic capacitors in there, which I am aware of.

 

[rbranco]

Orange disc top left between the two transformers.

 

[Harry Bloomfield]

Orange disc top left between the two transformers.

I think that will be a mains anti-surge component SPD(?). Are you sure that is the source of the buzz? It needs to be replaced urgently if it is.

 

[rbranco]

It's marked C which means capacitor, ceramic disk caps are fairly common to buzz and depends on frequency power supply is working and board design. Its not a tantalum one though as those are known to pop. I googled problem and buzzing ceramic caps can emit a piezoelectric effect.

I know the disc one is to blame as if you touch it then it goes quiet.

 

[Harry Bloomfield]

It's marked C which means capacitor, ceramic disk caps are fairly common to buzz and depends on frequency power supply is working and board design. Its not a tantalum one though as those are known to pop. I googled problem and buzzing ceramic caps can emit a piezoelectric effect.

I know the disc one is to blame as if you touch it then it goes quiet.

OK - Change its resonant frequency with a blob of silicon sealant maybe?

 

[rbranco]

I put some rubber tubing over it and yes it changed the frequency and made it quieter.
My mum can not hear it, I tend to hear quite high frequencies quite easily.
Switchmode power supplies run up around 10khz+ so people start to tail off what they can hear the older they get.