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Power Supply Short circuit? EE help me.

For the last month I have been doing an intense case mod.
Every wire is being soldered to fit my lengths...
Entire case assembly from scratch. Aluminum and plexiglass.
I have voided the warranty on almost every part of my PC.

What i am facing now is a power supply that appears to either overheat (my fault running without fans)
Or a short circuit in my wiring....worst case scenario(lots of wires to re-solder)

To test, I have removed every wire I could from the power supply(modular PSU).
I have just the psu connected to the wall. PSU is not connected to any other part(mobo/hdd/fans)


What I want to know is...

Should the heat sinks within the power supply carry a current?
I am getting shocked when i touch ground and these heat sinks...



I under stand heat sinks are a vital part of wattage dissipation for the transistors. But I assumed they would not directly carry a voltage/current.

I have thoroughly checked my solders for short circuits and cannot find a culprit.

Any Electrical Engineers out there?
4 answers Last reply Best Answer
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  1. Best answer
    The heatsink part of the transistor is tied to its collector so whether its junction (to the heatsink) is insulted from the heatsink or tied to it are dependant on the circuit design.

    With the PSU off and unplugged from the wall, is the heatsink tied to ground? (check for 0 resistance between the heatsink and the groundwire of the plug, you know that round 3rd leg) If you're showing it is grounded then you can investigate why/where your case is losing ground (which it typically picks up thru the PSU)
  2. Thanks for the suggestion popatim,

    I unplugged the p.s.u from wall and checked heat sink to ground. I found infinite resistance on all three heat sinks to ground.

    you say "its dependant on the circuit design", does that mean you might expect to see voltage on a heatsink?

    BTW: while p.s.u is powered up, i have 56.2 volts from heat sink to ground. 115 volts from power to ground.
    two of the three heat sinks have 56.2V.
  3. Best answer selected by diox8tony.
  4. I'm going to assume the reason for my 2 randoms shutdowns was not my mad amounts of cutting wires/metal.

    I'm going to assume that opening my power supply and touching it with my fingers is the reason I'm experiencing a shock, and that it is normal. :) Afterall, my computer runs just fine.

    I may have to put up a barrier or something to avoid electrocution during "open case" operation.

    I can't test the outputs on the power supply to mobo/hdd/cpu/vga because of the "soft on" switch internal to the p.s.u.

    I.E. the p.s.u does not send voltage to the mobo until the mobo requests it.
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