*random* Who's bright idea was it to make PSU heatsinks electrically 'hot'?

My younger brother put a lamp on wet soil that was in a radio flyer wagon. I touched the soil and I felt electricity going through my hand and lower arm. It didn't hurt though. Kind of felt funny. I was aware I wasn't going to be hurt before I did it if anyone thinks I was being a moron.
 
Originally posted by Banderon
Arrhythmia. If you've been shocked hard enough that the effects don't go away almost immediatly, it's a VERY good idea to go have yourself checked up. You might think you're fine, but be in pretty bad condition. If you feel "funny", it might be your heart dealing poorly with the unexpected electricity.

Also, electrical burns leave very small traces on the surface, while screwing up the inside of the body in an expanding arc from the point of contact.
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Hmm.... Maybe it would be best if I just pretended that I didn't hear that... :rolleyes:

...Especially that last sentence you wrote *shudder*
 
I feel the need tp add a story of mine here...

About three years ago, I was doing some work on a Gas Chromatographs PSU. I had taken great care at shorting each capacitator by holding a 1kilo-ohm Resistor to its Terminals. Little did I know, there was an oscillator inside the actual Chromatograph, which was connected to the PSU by a bunch of wires solderd onto its board. This oscillator contained two capacitators of 2.1 Farad each, at twelve volts. That ios a _lot_ of charge. Sind I couldn't see these caps directly, just their aforementioned bunch of wires, I didn't discharge them.

I was happily unsoldering a bunt Mosfet, leaning on the chromatograph case (ground) for support, when my hand probably hit the terminals for the oscillator circuit.

Suprisingly, there was no pain at first. I had a unpleasant tugging sensation in my left side, from my hand down to about my middle abdomen, via my shoulder. My vision dimmed, and a strange warm feeling settled in. Aside from that, and some shaky legs, everything was fine. I grabbed a cup of the and stretched out on a table, since I _was_ a bit woozy, but I was feeling quite fine for the next quarter of an hour. The symptoms of the shock went way, except for a hint of that warm feeling.

Then I slowly started to get chest pains, which seemed to grow exponentially. I noticed a strange sound in my ears, later identified as my own extremely arrythmic heartbeat. My vision graying out, I was rushed to hospital, and manaaged to escape with my life. My heart was lesss fortuante, pacemaker for me :(

Doc said what happened to me was a low-voltage, high-amp electrocution, which is usually fatal because you don't notice it until it is too late. It is quite normal for victims to feel fine for up to an Hour after the initial shock, but the small nerve node which controllls Heartbeat is fatally damaged, necessitating a pacemaker, and causing cardiac arrythma which eventually leads to fibrillation and a cardiac arrest.

Just wanted to let you know. When shocked, stay around other people and a phone for at least two hours.
 
If it hasn't been answered yet, the heatsink is usually on the collector of the transistors, where most of the current is. I've seen them on the emitter, though, too. Anyway, it is "hot", because to transfer the heat from the transistor to the sink, there has to be good contact, usually meaning metal to metal, which will conduct.
 
Little Grabbi:
I was rushed to hospital, and manaaged to escape with my life. My heart was lesss fortuante, pacemaker for me
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:eek: Yow dude! Thanks for the tip .:cool:
 
ok so a completely unplugged PSU can even carry electricity?

i was just working on my old gateway 90w PSU a few weeks ago putting a new fan in it that didnt squeal like a piggy, i guess i didnt get shocked

[/teen ignorance]
 
I was just reading all of these posts and thinking, Wow a lot of people have gotten shocked here and not died. Then I thought, Oh wait dead people don't tell their stories of forms....
 
Originally posted by retardedchicken
ok so a completely unplugged PSU can even carry electricity?
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To answer your question, yes, an unplugged PSU can still shock the hell outta you as the capacitors continue to carry a charge for quite some time. However, it would take some effort (or some extreme carelessness) to get nailed by the larger capacitors in your average computer power supply. The difference between your question and what happened to me is that I had the PSU plugged in and running because I was testing it after tinkering with some stuff.

Little Grabbi: Damn, 2.1F each!?!! :eek: Wow, that really sucks. I suppose I'm fortunate not to have touched something with even more amps going through it than that heatsink. :rolleyes:
 
Originally posted by retardedchicken
ok so a completely unplugged PSU can even carry electricity?

i was just working on my old gateway 90w PSU a few weeks ago putting a new fan in it that didnt squeal like a piggy, i guess i didnt get shocked

[/teen ignorance]
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PSU's have capacitors in them. Capacitors are put into circuits and basically act like a battery, they charge up... and after the power is turned off, they slowly slowly discharge... larger caps can take days (and longer) to discharge. you have to discharge the capacitor before it's safe to work on, just like you'd have to discharge a car battery before it'd be safe to connect the two terminals.


Gabbi: whoa, 2.1F caps? that's huge :eek:

and thanks for the tip... next time i get shocked i'll make sure to stick around people for awhile... or rig up a heart monitor operational amplifier and borrow an oscope ;)
 
Originally posted by Little Grabbi
I feel the need tp add a story of mine here...
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great story. Closely related: I will never even think about opening a PSU now
 
Originally posted by Ugly_Jim
I will never even think about opening a PSU now
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I don't see why anything in this thread should discourage (or encourage) you to open up a PSU as it really isn't that dangerous so long as you are super careful and take your time. Though, this coming from someone who, not two days ago, fried himself while modding a PSU may or may not mean very much :rolleyes: . Anyway, I plan to keep on modding 'till the day I die (which, hopefully, will be a somewhat more "natural" death... :p ).

Note to self: Maybe I should start following my own advice... :D
 
I have opened dozens of PSU's. I know what a cap is, and that it holds electrical charge. I never once touched anything other than what I was working on, and never once got a charge, tingle, or any other collateral damage from frying myself (because I didn't fry myself). :p
 
As long as you allow plenty of time from disconnecting the power source to opening the case up, there should be no trouble. And, keep clear of the caps.
 
retardedchicken said:
i was just working on my old gateway 90w PSU a few weeks ago putting a new fan in it that didnt squeal like a piggy, i guess i didnt get shocked
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:D "squeal like a piggy" :D ROTFL

thanx: i need a good laugh once in a while.
 
I took my psu apart, I knew there was a risk of being shocked but I never thought of it as life threatening. I guess I thought unplugging it was good enough to avoid electrocution.
 
Originally posted by Wixard
When i was little i used to stick my pinky finger in sockets, yea..the makings of a rocket scientist.
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same! :D its also fun to put rc anntennas across a plug (big spark ;) did that too when i was young) now I dont remember this, but when I was real young somehow i started an electrical fire from an outlet, and it left a big burn mark up the wall.
 
Originally posted by Rakinos
same! :D its also fun to put rc anntennas across a plug (big spark ;) did that too when i was young) now I dont remember this, but when I was real young somehow i started an electrical fire from an outlet, and it left a big burn mark up the wall.
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I managed to insert a piece of wire into a wall socket, but it didn't leave a mark or anything. :p It did make a massive spark. I also managed to remove it from the wall without being shocked.
 
Anything to do with power probably has capacitors, and any capacitor has the *heheh* "capacity" to shock you. It's just being aware of it and taking necessary precautions (if the possibility of high current exists).

I'm an EMT, and around here (NJ) electrical shocks are considered immediate emergency transports, with paramedic assistance. Electricity is a bitch cause it's what our body runs on. Our brain is all electricity, but power rarely travels upwards. Instead it hits the heart (who's timing is controlled electronically) and travels along the spinal column. Any shock strong enough to travel beyond the general area of contact should be grounds to see a doctor immediatly, since that means there was enough current to travel along the nerves (who's very job is transferring electrical signals) through all the flesh (which is possibly severly burned underneath the skin). In essence, thanks to our nervous system, our bodies are pre-wired to transmit electricity.

No one should be discouraged from working on PSUs... just be smart about it. You wouldn't rewire your house with wet hands, or clime a tree in a lightening storm. It's all just common sense.
 
I've opened psus and plan on doing so again, if not to just replace fans. I overreacted after reading such a story. I plugged my erector set motor into the wall as a kid. I think most people on this forum are guilty of these mistakes as a kid :-]
 
Originally posted by Banderon
No one should be discouraged from working on PSUs... just be smart about it. You wouldn't rewire your house with wet hands, or clime a tree in a lightening storm. It's all just common sense.
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Should I be concerned? I've climed trees in lightning storms before. :p
 
Man, I should have been dead a long time ago. Ten years as an electrician, you get hit a fair amount. Plus everytime I run my arc welder, I seem to get a low voltage, high amperage shock. I am gonna get me some good gloves before I do any more welding on my desk!
 
High amps? How high? If >100, its a miracle you aren't dead yet, unless we're talking about less than half a volt (--> 50 watts power)

I know it's a stupid question, but did you ensure that your welding table is grounded, while you yourself are not? Maybe you've got ground contact through a slightly conductive material.
 
ahhh its all good, im my life i have been zaped at least 3 times by a open powered PSU that i can remember...along with the suction cup ontop of the tube inside the monitor (blacked out)....ohh yea then there was the insident with the 440v line at work...that one sent me to the emergency room... :)
 
Originally posted by Little Grabbi
High amps? How high? If >100, its a miracle you aren't dead yet, unless we're talking about less than half a volt (--> 50 watts power)

I know it's a stupid question, but did you ensure that your welding table is grounded, while you yourself are not? Maybe you've got ground contact through a slightly conductive material.
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I very rarely work on a welding table. Most of my projects are done laying on the concrete. I frequently weld with 3/16 7018 rod running 125 amps and if I remember correctly its about 9-12 volts. I have taken more than one hit that hurt thru the years. I have been shocked so many times that I never realy considered the posiblity of a low voltage, high current shock doing permanant, irreversable damage. My welder will run up to 225 amps, man good thing I was not welding big stuff!
 
I have never stuck anything metal into a wall socket. Strange kids you are.

But I have been shocked by little things quite a few times:

I was using one of those motorized knives you use to cut turkeys, the casing was cracked and there was some metal exposed, so I shocked myself about 3 times before I knew what was happening.

I stuck my finger in a lamp when I was changing the bulb, done that about twice, pretty fun.

Had a sock on my foot and was rubbing it across the tv screen while playing sega genesis, I got shocked in my hand through the controller! Did that on my playstation, and sega saturn. lol.

Just last week I was running wires for our phone system here at work, I was stripping the end of the wire with my teeth, both of them touched and I got shocked in my tooth.

I was shadowing a electrician who was installing the wire for a new house being built, he told me to install a wall outlet for a bathroom, I did and accidently touched two wires together and my left arm felt real weird for like 10 minutes.

That's it! I'm 20 and have those shocks under my belt. I have opened many psu's to salvage fans. And I work on my car audio system ALOT with it's 1.5 farad cap and haven't gotten shocked...yet.
 
Welcom to the 120 VAC club Petra. My first byte (not the last) came while working on a DC rectifier. I was walking back and fourth between it and the breaker. Finally I trthough my scredriver in the hot lead of the AC then started to turn the screw, then I touched the steel of the rectifier and bam. It was 220 vac supply but because I touched the grounding it only amounted to 120 VAC and since I only brushed it, it wasn't so bad. Bahhhh AC isn't a big deal. Wakes you up too!!!
 
Originally posted by st4rk
Just last week I was running wires for our phone system here at work, I was stripping the end of the wire with my teeth, both of them touched and I got shocked in my tooth.
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Yep, When it comes to my PC I never use wire cutters. Sooner or later this will get me. Gott love those small wires. Plus spitting them out is fun!!
 
Just to make me feel better, would rubber gloves totally protect me from being shocked?
 
If they were true rubber gloves they would. Unless you got ahold of an extremely high voltage or touching something conductive with something other than your hands.
 
I had a small brush with 230V just recently, and, well, since I'm reading this, etc.

I was bothering with an automatic breaker, (one of 30 or so), which apparently was loaded just below it's max, but the extra surge of turning the tablefulls of computers it fed on again took it out again. I ended up standing by the breaker table while some others turned things off. At some point, I just half-heartedly stick my hand in to flip it down (again), and discover that yes, the metal sticking up on top of an automatic breaker is live. Bzzz, and all that.
Just between two fingers, no harm done, but a funky feeling :D

Also, two things learned:
1) Don't mess with anything above (low number) Watts when it's over 24 hours since you last slept
2) Never, ever think "that'd be unsafe, so of course they haven't ..."
 
I've personally been hit a few times. Let me tell you, AC may scare you a little bit, but DC does a hell of a lot more damage. I got zapped by a monitor once, that hurt. From what I've been told, the alternating current nature of AC can actually help you break the current (Like if you're holding a hot plug), but DC is a little less forgiving. Largest hit I ever took was 220V from a faulty plug. That was wierd. Felt it go from my hand, all the way down my arm, down to my leg. Let it go after a few seconds.

Matt.
 
Living in a 230V-only [1] country makes every mishap more shocking :D
Now, I imagine the DC system Edisons company once ran was ... interesting to work with in this regard. Can't remember the voltage, though.
(230V DC would have been nasty)



[1] Except the odd things that require 380V or more, but you're not likely to run into them.
 
Rubber gloves that are used for hydro workers safety are very thick and are kept in special pouches to protect them from sunlite and dirt. I dont believe the ones your mom uses to do dishes would work as well. I have been hit several times by voltage. Usually by something done by someone else, and a couple times by my own mistakes. I once got it from a t-bar cieling grid that got energized by a faulty lite fixture. Another time I was zapped by leakage current that had travelled from underground cables around 300yards to a piece of equipment I was installing. The cables had been scrapped by a digger. The problem was found after a piece of telephone equipment burned off the wall. So if you think there may be voltage use caution. That tingle from 120volts aint bad 240 is not fun and 347 is often fatal. It's also very hard on tools. The little molten drops of copper are not good for your eyes either. The flash makes it very hard to see and of course the lites in the room you were in go out when you trip a main breaker. I have been working with electricity for over 20 years and have found that when you are tired or in a big hurry thats when the mistakes happen. It allways trys to find the shortest path to ground. Best you can do is try not to be that path.
 
Actually DC burns, AC kills. You can kill yourself with DC but most of the deaths from electricity are from AC. It's when it goes through your heart, giving you an irregular heartbeat or simply stopping your heart from pumping in the first place. That's the cause of most of the deaths. Either way if you get by 200 amps it'll cook you pretty effectively.
 
Originally posted by Alexia
It's aluminum that isn't magnetic.
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That's probably what I was thinking. I never thought to look into how conductive aluminum was before. :p
 
Originally posted by Anarchist4000
Actually DC burns, AC kills. You can kill yourself with DC but most of the deaths from electricity are from AC. It's when it goes through your heart, giving you an irregular heartbeat or simply stopping your heart from pumping in the first place. That's the cause of most of the deaths. Either way if you get by 200 amps it'll cook you pretty effectively.
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'
However, DC arcs better, so for higher voltages, it's harder to get away from.
I don't know if it's true that AC is easier to let go of due to how it interacts with your muscles/nerves, but I've heard it from a few different places, and from my last brush with AC, it feels possible.

AC can kill you in more ways, but DC will try to make up for it by holding on to you?
Sounds plausible to me :D
 
Originally posted by HHunt
AC can kill you in more ways, but DC will try to make up for it by holding on to you?
Sounds plausible to me :D
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Sounds like my last two girlfriends. :p
 
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