Questions about my near-death experience w/ power supply

[tangluva]

I was fixing and installing stuff on my friend's computer when Win98 said it would take 174 minutes to install. I wondered if the power supply wasn't giving enough power. I shrugged it off and told my friend to try to install the stuff himself.

The next day, he said he had to wait seven hours to install the thing and when it was almost done, it just shut down on him. No surge or anything. I tried to turn it on myself, but it just gave a static noise. I thought that it had to be the power supply, so I OPENED THE COVER UP TO SEE THE PROBLEM FOR MYSELF. Once I opened it, I saw it was very dirty inside, so I left the thing open and clean it once I got a can of compressed air.

Day after that, I finally bought the stuff and dusted the power supply. But then after I screwed the cover back on, I saw a prompt on the cover saying "CAUTION. Do not open this cover." I wondered, why the hell would it tell me not to open it when I just did and nothing happened? Since I was actually bold enough to try it, I plugged in the power supply. It worked fine and nothing bad happened! So I asked my brother about it and he said I could've been electricuted by some power left over!

I was suprised! He told me to just trash the supply, but he thinks that it was because of no electrical grounding. What do you think? Was that the reason or not? Plus, should I keep using the supply or just buy a new one?

[Jonty]

I don't know what the answer to the long install would be, but I remember reading somewhere about people being electrocuted when tinkering about inside TV sets. Due to the high voltage inside these devices (25kv) even with the set unplugged if you touch certain parts you could get electrocuted.
I also remember reading a case of someone just touching the pins of the mains plug and getting a shock! Apparently there was nothing wrong with the TV too.

Perhaps the manufacturer of the computer thought it best to put this warning on the case to be on the safe side?

[Nater21]

There is a danger in being electrocuted when removing the cover of a power supply. There is this nifty little device, perhaps you've heard of it, it's called a CAPACITOR. What it does is store energy. When you unplug the Power supply, the stored energy is often kept in the capacitors. If you happen to touch the worng side of the capacitor when you are connected straight to ground, the capacitor will discharge through you. This is known as an electrical SHOCK. Anyways, be careful next time.

[Jeff7]

I've opened 2 power supplies already - the same problem both times - dying fans. Just splice a new fan in the power supply in place of the dead one.It's extremely easy to do - just don't touch anything metal. http://sysopt.earthweb.com/forum/smile.gif

[qball]

I still drink Tang...

Nater21, I second your post.

tangluva, in answer to your question, you were either not grounded, or just very lucky to not touch a CAPACITOR (I'm going with luckey). I would trash the PSU and buy another, as they are cheap and goofing around with the old PSU has potentially created a fire/shock hazard (sure it works fine now, but when it gets hot enough to ignite that little piece of dust you missed....).

[tangluva]

Yeah, I trashed the old supply and just bought a complete tower instead. Better safe than sorry I guess!

[dgardner]

Funny what yousaid about TV's I have had shocks of the plug pins when unplugging the TV's to move them around the house, its a little worse than static. Also had a near death experiance with a PSU, one went in a tower case so I replaced it, was looking at the old one (didn't have the cover off) and had it in my hand when someone turned on the wrong plug and the PSU started up, well the earth was on the outside of the case and the blo*dy thing electricuted me, someone had to kick the thing out my hand cause I couldn't let go. My arm was tingling for a week after that.

~Dave~

P.s. I dont mind if you laugh at my expense was my own stupid fault, luckly no serious damage done

[RataToo]

when my soft button for my atx power wasnt workin i took the liberty of pokin my nose in the power supply...there was a teeeny litle fuse saughtered to some other littly deelybop, and when I grabbed hold of it i realised that I hadnt unplugged the system yet the hard way. It not quite as bad as the shock you can give yourself when tinkering with your car stereo, but its enough to numb your arm for about twenty minutes.....my nipples are still hard...

[tangluva]

Thank you for sharing all of your experiences with me. I now feel like the luckiest man on Earth. http://sysopt.earthweb.com/forum/biggrin.gif

[skywalker[TSG]]

deja vu

i see flashbacks LoL

but then again i poked with a screwdriver in the PS when the power was on

[Randall]

hey check my reply on "ps". I posted it as a new topic instead of a reply

[socalgal]

So we don't lose track of your reply, Randall

http://sysopt.earthweb.com/forum/Forum16/HTML/000172.html

[Eli]

TVs can sit around unplugged for years and still shock someone. I'd imagine that under the right conditions a power supply could do the same.

I as well have opened a power supply to blow out the dust and replace the fan with no bad luck yet. I did replace that faulty piece of junk recently though.

[dgardner]

You want to open a PSU safely well then, going on my small knowledge of capacitors the best way to discharge one is to short it out! Now supposing we take this into account in a power pack, well I had a peek in mine at the weekend as I was replacing one anyway. And the capacitors inside arnt that big, most would hold a huge charge on there own but linked together is another story!!! Capacitors can hold there charge for years it depends on the quality of the insulator between the plates. But if you want to open one up the best way to make them safe of so I have been told is as follows!

1.Take and old power lead and cut the plug off (the one that goes into the wall)

2. Get a junction box and put the positive wire in one end and the negative in the other!

3. Seal up junction box so no bare wire is visable and is all well insulated.

4. Plug this lead into back of power supply, turn power supply on and bingo circuit is shorted and therefore all capacitors should be discharged and safe for you to fiddle.

Please note I do not take any responsability for your actions or any damage you may do (though I think is unlikly) when using this device!

I'd only ever suggest changing a fan in a PSU though anything else forget it, its not worth the risk buy a new one

Hope that helps

~Dave~

[shadow]

Death by electrocution has to have the right conditions. Namely your heart being in the path of the electricity. This happens if you are crazy enough to be hanging onto a good ground with one hand and poking around in some high current source with the other. You've just made your body, and thru your heart part of the circuit. Capacitors do hold a charge, as do CRT's in tv's and monitors but it's just a little blast, usually nothing serious. A rule of thumb when working in and around live electrical devices is to be aware of where that other hand is...sticking your one thumb up your a** is one way to be sure.

Don't fear electricity but do respect it. Most circuits do bleed off the stored voltage in capacitors when powered down but some will hold a nice little charge, of which I have been on the recieving end of a few times. I've also felt the stored charge on the anode of a crt as well as experiencing that 40,000 volts while the thing was on. I'm still here. It's best to avoid getting a shock by knowing a little about electricity and what it does. It flows from positive to negative. If you don't provide a circuit for it, the flow doesnt happen and no damage occurs.... usually. Play safe!

[lowcpuuser]

WOW...reminds of that time in my younger years changing the element in my oven and didn't unplug that puppy. One hell of a spark when it fell from my hands and hit the metal.
Whew...
live and learn

[ReRun]

Well, I've been around electricity most of my life. From my dads TV shop as a boy, an electronics tech in the navy, to 10 yrs with IBM as a service tech, and all the schools and hands on that all of this involved. Shadow is right about requiring the right conditions but I doubt that he got the full effect of being grounded good and a full 40000 running thru him or he wouldn't talk so lightly about it. He may have just got a portion of that 40k because of a poor ground or several other reasons. Under normal conditions electricity is gonna have the opposite effect of a paramedics shock paddles. It can stop or put ur heart in fribulation and this is caused by volts and frequency. But amp's it what you really gotta worry about because thats the part that will usually deal the fatal blow. And it doesn't take many of those puppy's to do a number on you. Any capacitive curcuit has the abillity to deliver a delayed shock and the best thing for everyone to remember is be safe not sorry and if you don't know what you're doing then just leave it alone. I've seen a TV capacitor jump a full 1 inch gap to a grounded probe just like lightning. So do go thinking that if I don't touch it I'll be safe.
Experience: when you're expecting one thing and get something totally different, thats an experience.