A screw loose

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mdogg
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A screw loose

Post by mdogg »

So yesterday, I was trying to test out a hard drive. I plugged it into an old PC to see if it worked. It did. So I turned off the PC and unplugged the hard drive. Just as I had unplugged it, I saw a big bright white spark and heard a very loud pop sound come from the PC (not the hard drive). It seemed that something in the PSU had blown because I don't think anything else in the PC would have enough voltage to make such a big spark and loud pop. I took out the PSU today and opened it up to see what had happened, and I found this:

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^ This is (I think) a choke.

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^ This is the fuse.

It should be fairly easy to see what's happened for those who know a lot about electronics, but for those who don't, I'll explain what I think happened. You can clearly see the burn marks in that screw which leads me to thinking that the screw came loose over time and while I had been moving the PC around, the screw had been moving around that corner of the PSU. Eventually it got in just the right spot and short circuited the choke, creating the spark and enough heat to melt the solder joint which made the screw fall in soldering itself to the board and the choke. A side effect of this short circuit was the fuse blowing which made the loud pop sound and perhaps contributed to the spark. At least, that's how I think it happened.

I guess this shows that loose screws do cause many issues.
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inxsfan92
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Post by inxsfan92 »

i too had a PSU blow on me

i was working on installing a new video card in my old 233mhz pII

turned it on a poof a bright white light some smoke. one of those memorable experiences. lol

win98
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Post by win98 »

I've had a simular 2 experiences.
1 When i over heated the chip on an hdd (crappy compaq psu) and smoke curled out and the other when i shorted out a floppy drive and the psu wires to it melted and almost caught on fire.

___
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Post by ___ »

lucky it was an old computer and not an expensive part of a new one

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Post by XDude »

desolder the screw and replace the fuse?

mdogg
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Post by mdogg »

XDude wrote:desolder the screw and replace the fuse?
I think it would be more sufficient to just get a new PSU in there as firstly, there may be more damage in their that I can't see, and I don't really want to mess around with soldering something that's easily replaceable. Besides, I didn't post this here because I needed help. I just thought it was very interesting as nothing like this had ever happened to me.
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Rob Jansen
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Post by Rob Jansen »

Doesnt anyone read the notices about:

DANGER!
DO NOT OPEN, HIGH VOLTAGE!



The warnings arent just there for not reading or fun.
The main components always have much voltage and amperes left inside them.

I know it, i almost have been electrecuted when i was about 6/7.
Running 230 volts trought your body is.... electryfying and a hell of a rush...

If the fuse is blown its blown for a reason more then only 1 screw lose.

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Post by Koptor »

DjRob wrote:Doesnt anyone read the notices about:

DANGER!
DO NOT OPEN, HIGH VOLTAGE!



The warnings arent just there for not reading or fun.
The main components always have much voltage and amperes left inside them.

I know it, i almost have been electrecuted when i was about 6/7.
Running 230 volts trought your body is.... electryfying and a hell of a rush...

If the fuse is blown its blown for a reason more then only 1 screw lose.
lol...

For a start, it's not high voltage, as HV is classed as anything over 1000v. The only time you'll get a bang from opening up a power supply is if you do so whilst it's still plugged in, or if you don't let the capacitors discharge...easiest way to discharge them is by connecting some sort of load, a multimeter will normally suffice.

Almost electrocuted? Mmkay...

230 volts is alright, as long as you don't get it flowing across your chest, that's when your heart starts to fail. But bear in mind that it's not the voltage that kills you - its the amps. 30mA of current flowing across the heart is enough to stop it (hence why nearly all domestic RCDs are rated as such...)

And the fuse is probably only blown due to the short caused by the screw...it looks like the screw has shorted the choke to earth, this causing a higher current flow than the rating of the fuse, blowing it...

Though I do agree that it's not really worth repairing...for the amount of money they cost, it's just not worth the effort...

And just in case anyone wishes to dispute the accuracy of my answers, may I add that I'm a 17th edition qualified electrician...
lol, internet

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Post by XDude »

Koptor is right, you can't kill yourself with 230V nor opening a PSU unless youre doing something stupid.

I had open a few PSU before and I'm still typing this post normally.

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Post by QuiescentWonder »

You wouldn't die from 100,000 volts if there wasn't enough current. 1 Amp will kill a person AFAIK. Also, capacitors can take a long long time to discharge. You can still electrocute yourself, be careful. It's not even worth the risk, new power supplies cost next to nothing anyway.

EDIT: Looks like koptor already has it covered.

yifanlu

Post by yifanlu »

This reminded me of the time I killed my computer with a bad usb printer.

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Post by hypr »

how did it happen?

I also did some carpentry work when I was touching the live wire of an outlet, just got little jolts from it, as I wasn't really paying attention.

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Post by Andy »

QuiescentWonder wrote:You wouldn't die from 100,000 volts if there wasn't enough current. 1 Amp will kill a person AFAIK. Also, capacitors can take a long long time to discharge. You can still electrocute yourself, be careful. It's not even worth the risk, new power supplies cost next to nothing anyway.

EDIT: Looks like koptor already has it covered.
15mA will make your heart spasm, 30mA or more will kill you. 1A would fry you.

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Post by Koptor »

QuiescentWonder wrote:You wouldn't die from 100,000 volts if there wasn't enough current.
Indeed, we regularly use the insulation testers at work to shock each other, and they are set at either 500v or 1000v, but because there's so little current, all you get is your muscles tensing and it wakes you up a bit...useful first thing on a Monday morning
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Post by Andy »

Koptor wrote:
QuiescentWonder wrote:You wouldn't die from 100,000 volts if there wasn't enough current.
Indeed, we regularly use the insulation testers at work to shock each other, and they are set at either 500v or 1000v, but because there's so little current, all you get is your muscles tensing and it wakes you up a bit...useful first thing on a Monday morning

Lmao. I must remember that one. My mate is an electrician and he is planning on getting one soon, so I'll use it on him

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Post by happy dude »

Ya know... when I saw the topic.. I thought it was a rant about Andy...

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Post by Gnome »

Koptor wrote:
QuiescentWonder wrote:You wouldn't die from 100,000 volts if there wasn't enough current.
Indeed, we regularly use the insulation testers at work to shock each other, and they are set at either 500v or 1000v, but because there's so little current, all you get is your muscles tensing and it wakes you up a bit...useful first thing on a Monday morning
I think ill get school read that. Would makes us work better XD

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