[charlo89]

Hello,
My m3 worked perfectly a few days ago. But since one week I hear noise. Impossible to remove with a ground locker. But when I isolate the potentiometer chassis the noise disappears. But it is impossible in my setup to isolate it. More ever recently when I turn on the M3 the ground louker smokes at the capacitor.
I use this method:

I think that a component is dead on the ground channel, but I have no idea of the culprit.
Thank you for helping me.

Best regards Charles

 

[FallenAngel]

Please post photos and wiring scheme.  Smoking capacitor is VERY scary.

 

[nikongod]

I think its also important to know what the rest of your system looks like.
 
If you are using a computer as source, is V- on your σ11 tied to earth ground? 

 

[charlo89]

I use a power supply Vellman http://www.velleman.eu/distributor/products/view/?id=8904
I have some old photo when I used a O11 but the O11 died. http://www.head-fi.org/forum/thread/511647/pics-amb-my-m3#post_6915385
I do not have the amp with to me, I will take some more recent photos this weekend.
This does not smoke exactly on the capacitor but on the intersection of the capacitor and resistor 10ohm on the ground loop breaker.
 
thank you

 

[nikongod]

Are you using a computer as your source?
 
Is V- on the power supply you have connected to earth ground?

 

[charlo89]

I use a gamma2 DAC as source. 
But the intersection smoke when there is analogique source or not.

 

[nikongod]

Is your power supply's output grounded to earth ground?

 

[charlo89]

No my power supply is isolated from the chassis and they don't have output ground on it.

 

[nikongod]

EEK! the PowerSupply should be isolated from the chassis. 
 
Ground on the M3 board is 1/2(power supply)V above V- assuming you have a 24V supply, you tied 12V to ground through a 10ohm resistor... this burns off ~14.5W. If your power supply is higher than 24V you are burning off more power. 

 

[charlo89]

Thank you

 
I must therefore place stronger resistance? like 100Ohm ?

 

[FallenAngel]

No, you simply shouldn't have V- connected to chassis.

 

[nikongod]

 
Quote:

No, you simply shouldn't have V- connected to chassis.

+1

 

[qusp]

this is worrying, I wonder what happened to the S11......

 

[charlo89]

 
my transformer 220v 30va destroyed 2 S11, I prefer to forget the S11 and buy a PSU Vellman
But the problem is that my PSU is isolated from the chassis. V- and V+ aren't connected to the chassis.

 

[FallenAngel]

If your transformer destroyed your PSU, then something is VERY wrong, and it's probably not with the transformer, it's likely the wiring.  Can you make absolutely sure that V- on the amp board is not connected to chassis?