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With test light I can detect voltage on my desktop pc case and I believe it's the reason that my HDD fails some often or my pc hangs. When I connect my case to ground (metal door frame) it works with no problem.

I have disassembled my pc and found that the leak is from power supply unit (as you have guessed). I have replace the power supply with a new one but I still have the same problem.

Any idea how to repair it or what the problem is?!

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migrated from electronics.stackexchange.com Aug 14 '11 at 17:59

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1  
Is there a problem with the case grounding? Look to see if it is internally if it is then check to see if it has good conductivity. –  Dean Aug 14 '11 at 8:36
    
Check to see if any parts of the motherboard are hitting the metal case (are you sure you used the proper spacers?). –  Breakthrough Aug 14 '11 at 18:18

1 Answer 1

There should be no significant voltage between any combination of

  • Your power supply ground

  • Your case

  • Your grounded door frame.

You have some unrelated fault OR the problem described below.

Do you measure a Voltage between power supply or case and door frame when the PC power is turned off at the PC?

Is the PC case grounded to the power supply ground (as it should be)?

Note that "Y" filter caps across a power supply between both mains lines and ground will place a high impedance capacitively coupled half-mains voltage on a floating ground such as the power supply output if it is not grounded.

Use of a ground lead to the PC in it's power cord to a proper local ground will remove this capacitively coupled voltage. (These may be about 0.01 microfarad each. They can convey enough energy to do major damage in some cases.)

The capacitors are required by many regulatory authorities.

What country are you in?

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