Computer grounding

[boyofwax]

Hi all ! I experiment a lot with homebuild amplifiers, and use my PC as sound source when doing so. Since my PC is not grounded it gives a lot of hum (50Hz were I live), and puts half of the supply on the case, which I don't like :@ . What can I do besides grounding ? Anybody ever took out the 2 caps (?) to ground ?

When I do ground my PC with a clamp there are spraks, and sometimes I makes the earthleak (?) switch !

Anybody ever fed his PC with a convensional power supply (transformer) ?

[djmiddelkoop]

Don't take out these caps for safety and noise ( CE normering ).

Just use an isolation transformer.
If you don't have, send me a mail.

Dick.

[w00t]

Seems like you have got a bad PSU for your computer. Ever thought of changing it?

[djmiddelkoop]

No, there is nothing wrong with the powersupply.

It's normal that half of the line voltage appears on the case when the earth connection is not made. This is due to internal circuitry, safety and filtering actually. So when a conection is made, sparks could be seen and the earthleak detector could come in. These trigger normally at 30mA here in the Netherlands.

So due to the above hum can be heard when connecting to other equipment.

Either you ground your PC powersupply properly or isolate both equipment with a signal transformer.

Dick.

[w00t]

Originally posted by djmiddelkoop
No, there is nothing wrong with the powersupply.

It's normal that half of the line voltage appears on the case when the earth connection is not made. This is due to internal circuitry, safety and filtering actually. So when a conection is made, sparks could be seen and the earthleak detector could come in. These trigger normally at 30mA here in the Netherlands.

So due to the above hum can be heard when connecting to other equipment.

Either you ground your PC powersupply properly or isolate both equipment with a signal transformer.

Dick.

I have opened up a few PC power supplies before and noticed that they are all connected to the circuitry only through the Earthing wire. No other part is in contact with the chassis. AFAIK, there should not be half wave appearing on the chassis.