Discharging PSU so it won't kill you?

Thread Starter

gloves10101

Joined Aug 18, 2013
7
Hello

I just saw a news report from 2012 saying that a boy was killed after he got electrocuted from a computer PSU he was disassembling, and the computer was unplugged. It was said that the capacitors were still charged so they killed the boy.

Is it a true story? Does a computer PSU really have the power to kill you even when it's unplugged? If so, what do I need to do to avoid it?

Thanks!
 

#12

Joined Nov 30, 2010
18,224
Use 2 alligator clips to attach a resistor across each large capacitor. 27K, 2 watt and a discharge time of most of a minute.
 

MaxHeadRoom

Joined Jul 18, 2013
28,702
Hello

I just saw a news report from 2012 saying that a boy was killed after he got electrocuted from a computer PSU he was disassembling, and the computer was unplugged. It was said that the capacitors were still charged so they killed the boy.

Is it a true story? Does a computer PSU really have the power to kill you even when it's unplugged? If so, what do I need to do to avoid it?

Thanks!
Personally I find that hard to believe, No.1 on the high voltage, AC input side, there is no large caps, and all the P.C. supplies I have serviced most of the caps of any significance is on the low voltage side.
Besides, a P.C. supply is a switching supply and a largely operates with low impedance circuitry.
Was it really unplugged?:rolleyes:
Max.
 

paulktreg

Joined Jun 2, 2008
835
Personally I find that hard to believe, No.1 on the high voltage, AC input side, there is no large caps, and all the P.C. supplies I have serviced most of the caps of any significance is on the low voltage side.
Besides, a P.C. supply is a switching supply and a largely operates with low impedance circuitry.
Was it really unplugged?:rolleyes:
Max.
?

Most PC power supplies have an electrolytic capacitor of about 330/470uF with 300VDC + across them on the primary side. I count this as a significant maybe others don't?
 

THE_RB

Joined Feb 11, 2008
5,438
Nah, I side with Max on this one. There is a good chunk of energy in that cap, but it's unlikely to cause death from a single event 160v or 320v DC cap discharge.

It's more likely in my opinion the boy was killed from a live PSU from a sustained exposure to AC mains voltage, which causes heart failure.

I would fully expect someone finding the situation to have unplugged the live device and then maybe try to state it was not massive negligence on behalf of the boy (touching a live supply) but instead was "a lethal shock from the caps, even though my son was not at fault" etc.
 
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