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Is it dangerous to change the fan on a PSU?
- Thread starter jimmybates
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ive seen a article that say's leave a psu unplugged for a week to discharge all the power.
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Personally if its annoying you that much I would sell the PSU and put the dosh towards a new known quieter PSU & still be alive to enjoy it 
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Changing the fan is a doddle. Avoiding a nasty sting requires you have your wits about you.
disconnect the PC from the mains, let it drain. But, you'll be avoiding the capacitors anyway.
Take note of where the HV and LV sides of the power supply are, the are almost always clearly deliniated. Simple rule, nothing on the LV side will do more than make you go "ooooch", and that's if you are a consumate pillock and shove sweaty paws onto the pins of the caps. Nothing on the HV side of the PSU is any of your business, "THIS WAY BE DRAGONS!!!", mess with anything on that side without being fully qualified and in possession of the PSU's service manual, and you die/fry your PC/set fire to your wife and kids.
Last time I had to change a fan, the connector was a bitch to get to, I could get the old fan off, but no way could I squeeze the new connector in between the caps, and trannies and what have you, obviously I didn't want to mechanically stress any component....so I fitted the new fan, ran it's cable through beside the main multicore, and hooked it up to the Molex loom. I musta stared at it for 20mins running it round and round in my head, convinced I MUST be breaking some fundamental electrical rule. But of course I wasn't, fan was running off the same power, from same place,only the connector had moved. Still, any PSU mod should be checked about 3 dozen times mentally, visually and MOST importantly, mechanically before you even think of hitting that switch.
Remember, ickle wires and ickle components= ickle voltage (and even ickler chance of any appreciable residual charge). Thick wires, big bruisey components and heavy solder tags=big volts=bzzzzzzzzzzt THUMP (potentially even when off, although the caps in PSU's are lightweights up against the HT supply caps in CRTs.....wanna set the olympic long jump record (posthumously by the time you land), shove one of those on your leg.)
Also...no terminal blocks, no tape and no bloody twist+hopes inside the PSU chassis, that way, again, dragons, big scaly bad tempered ones.
If you really are a total numpty, get someone else to do it, one of your mates will have a dad who can field strip a live television without it blinking, ask him to do it.
And if you really wanna do it yourself....take sollace from the fact that 240v PROBABLY wont kill you, or I'd not be here.
Worst thing I ever seen was someone sit on a live benchrigged PSU for a Moog synth, not sure what was funnier, the look on the guys face as 240V when up his tradesman's, or the fact the the Moog did a little Whoop up in pitch when he did it.
Of course YMMV and a teeny jolt could leave you a martyr to MHz
disconnect the PC from the mains, let it drain. But, you'll be avoiding the capacitors anyway.
Take note of where the HV and LV sides of the power supply are, the are almost always clearly deliniated. Simple rule, nothing on the LV side will do more than make you go "ooooch", and that's if you are a consumate pillock and shove sweaty paws onto the pins of the caps. Nothing on the HV side of the PSU is any of your business, "THIS WAY BE DRAGONS!!!", mess with anything on that side without being fully qualified and in possession of the PSU's service manual, and you die/fry your PC/set fire to your wife and kids.
Last time I had to change a fan, the connector was a bitch to get to, I could get the old fan off, but no way could I squeeze the new connector in between the caps, and trannies and what have you, obviously I didn't want to mechanically stress any component....so I fitted the new fan, ran it's cable through beside the main multicore, and hooked it up to the Molex loom. I musta stared at it for 20mins running it round and round in my head, convinced I MUST be breaking some fundamental electrical rule. But of course I wasn't, fan was running off the same power, from same place,only the connector had moved. Still, any PSU mod should be checked about 3 dozen times mentally, visually and MOST importantly, mechanically before you even think of hitting that switch.
Remember, ickle wires and ickle components= ickle voltage (and even ickler chance of any appreciable residual charge). Thick wires, big bruisey components and heavy solder tags=big volts=bzzzzzzzzzzt THUMP (potentially even when off, although the caps in PSU's are lightweights up against the HT supply caps in CRTs.....wanna set the olympic long jump record (posthumously by the time you land), shove one of those on your leg.)
Also...no terminal blocks, no tape and no bloody twist+hopes inside the PSU chassis, that way, again, dragons, big scaly bad tempered ones.
If you really are a total numpty, get someone else to do it, one of your mates will have a dad who can field strip a live television without it blinking, ask him to do it.
And if you really wanna do it yourself....take sollace from the fact that 240v PROBABLY wont kill you, or I'd not be here.
Worst thing I ever seen was someone sit on a live benchrigged PSU for a Moog synth, not sure what was funnier, the look on the guys face as 240V when up his tradesman's, or the fact the the Moog did a little Whoop up in pitch when he did it.
Of course YMMV and a teeny jolt could leave you a martyr to MHz
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Carlsboro 100W valve guitar amp.
There were two u-nail like things on the back. One was for selected the impedance of the cabinet between 4 8 or 16 ohms. The other, was for selcting between, deadly, really deadly and absolutely psychotic voltage for the enormous valves.Obviously, no mere relay affair either, it physically routed the power through the right circuits.
Can you guess which of the u-nail thingies had the rubber cap missing?
I think you can.
I was in genuine shock for days, really dazed and dowright weird. Not recommended, must have been into the KV range!
Current must have been infinitesimal or I'd be a small piile of rusty carbon particles
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PSU's aren't the best chairs from what I've seen...Having 50Hz instead of 60Hz is nice tho, apparently it's less likely to cause a heart attack as it's further away from the average bpm of the human heart...
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Perfectly safe provided it's isolated.
Yes the Cap's inside can give you a little jolt but unless you have an extremly weak heart then they certainly don't store enough charge to significantly hurt you.
Yes the Cap's inside can give you a little jolt but unless you have an extremly weak heart then they certainly don't store enough charge to significantly hurt you.
You need to think whether risking your life over 30 quid is worth it?
If you know what you are doing like some of the experts here then fair enough but you aren't !
It's like jumping red light, or rail crossing barrier to save a few seconds just to get crushed to pieces.
Sell it, you wil get about 30 quid then get a Seasonic S12 II 500 for 55 quid, I can guarantee that you will be more than happy.
If you know what you are doing like some of the experts here then fair enough but you aren't !
It's like jumping red light, or rail crossing barrier to save a few seconds just to get crushed to pieces.
Sell it, you wil get about 30 quid then get a Seasonic S12 II 500 for 55 quid, I can guarantee that you will be more than happy.
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I know this is probably meant to be a totally serious thread and kudos for the advice but I couldn't help grinning at the last sentence!
Done it loads of times, its fine as long as oyu dont go wedging the screwdriver, or indeed your fingers into places they dont belong.
And switch your PC on, and then flick the power switch at the socket OFF, that way the PC tryign to come on will totally discharge any power in the PSU.
Just dont be silly, take your time and oyu will be fine.
And switch your PC on, and then flick the power switch at the socket OFF, that way the PC tryign to come on will totally discharge any power in the PSU.
Just dont be silly, take your time and oyu will be fine.
done it a few times too. never even thought of it as been dangerous really.
unplug PSU from mains. power it on to discharge the caps. open it up and just dont touch anything you dont need to touch
even if you do then nothing will happen if the caps are discharged. i just advise against it incase you damage it. dont want any nasty electrical fires one day !
you will get a little shock from the capacitors if not discharged and you touch them. nothing that would kill you though.
unplug PSU from mains. power it on to discharge the caps. open it up and just dont touch anything you dont need to touch
even if you do then nothing will happen if the caps are discharged. i just advise against it incase you damage it. dont want any nasty electrical fires one day !
you will get a little shock from the capacitors if not discharged and you touch them. nothing that would kill you though.
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Having 50Hz instead of 60Hz is nice tho, apparently it's less likely to cause a heart attack as it's further away from the average bpm of the human heart...
Lower frequencies are actually more harmful.
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Back in the days of Noah and the Ark, when I was a lad, I remember reading what was then an old magazine about DIY home electronics enthusiasts in the days of valves and mains radios the size of wardrobes. They had similar concerns to yours. The real danger is current passing across the chest through the heart.
Their advice was work on the equipment with one hand and keep one hand in your pocket - shocks up one arm only and hopefully your feet are earthed by decent shoes.
CRT monitors and power supplies are the only things I won't mess with. PC engineers like to discharge the stored energy in such devices by putting a screwdriver (insulated handle) across the terminals of big capacitors in such devices. Makes a very satisfying bang.
There is actually a little tool with a built in resistance to do the job less spectactularly.
Their advice was work on the equipment with one hand and keep one hand in your pocket - shocks up one arm only and hopefully your feet are earthed by decent shoes.
CRT monitors and power supplies are the only things I won't mess with. PC engineers like to discharge the stored energy in such devices by putting a screwdriver (insulated handle) across the terminals of big capacitors in such devices. Makes a very satisfying bang.
There is actually a little tool with a built in resistance to do the job less spectactularly.
True. The lads were told to hold their jewels and the lasses were told to use their imagination. LOL
Not quite right.
Normal people like to short the terminals of a cap when its out of any circuit.
Pricks, stupid people, and people who dont have a clue as to WTF they are doing like to do it when its still in a PSU.
The fact still remains that the big filter caps are going to be highly charged when you open it up. Advice given in here of 'press the power button while the mains lead is removed' isn't going to help that at all.Quite possibly some of the worst 'advice' I've ever read.
There are a few ways you can discharge them:
1. Short it with a screwdriver. As you imply, a crap idea. Dangerous, and would probably cause some damage to the circuit.
2. Connect up a socketed light bulb (say 100W).
3. Short it with a resistor (high wattage variety, say 10W). A few k should discharge it in a few seconds.