Can I reuse my PSU's fan?

[IAmAndre]

Hi,

 

I recently replaced my Bequiet PurePower PSU and I would like to know if I can reuse the 120mm fan that came with it. I have never opened a PSU before and I can see that it's not advised when you don't know what you're doing so before doing anything I'd like to know if it's possible. I would like to use this fan either as a case fan or a second fan on my CPU cooler in a push position.

 

Thanks

[Guest]

Opening your powersupply is a very bad idea if your don't 100% know what you're doing. Inside of them there are 120V capacitors which is enough to seriously injure or kill you.

[Guest]

6 minutes ago, Darpyface said:

 Inside of them there are 120V capacitors which is enough to seriously injure or kill you.

Actually around 400V.

[Tomthehitman]

8 minutes ago, IAmAndre said:

Hi,

 

I recently replaced my Bequiet PurePower PSU and I would like to know if I can reuse the 120mm fan that came with it. I have never a PSU before and I can see that it's not advised when you don't know what you're doing so before doing anything I'd like to know if it's possible. I would like to use this fan either as a case fan or a second fan in my CPU cooler in a push position.

 

Thanks

 

No, if you don't know what you're doing it's just not worth it.

 

Go buy a fan they don't cost that much.

[IAmAndre]

2 minutes ago, jonnyGURU said:

Actually around 400V.

 

9 minutes ago, Darpyface said:

Opening your powersupply is a very bad idea if your don't 100% know what you're doing. Inside of them there are 120V capacitors which is enough to seriously injure or kill you.

Alright good to know. Now I'm just curious, how could these capacitors injure me even with the PSU unplugged? Also I realized that this PSU was getting a bit noisier than usual and when I replaced I was barely able to touch it because there was too much static electricity. I tried everything from pressing the PC's power button to touching the case. I also noticed a lot of static electricity on the hard drives and the motherboard. I ended using the bubble wrap that came with it to take it off. Any idea why that happened?

[Tomthehitman]

3 minutes ago, IAmAndre said:

 

Alright good to know. Now I'm just curious, how could these capacitors injure me even with the PSU unplugged?

The capacitors inside the PSU can hold a large charge for quite some time after it has been removed from the power. If you touch something that you shouldn't while messing around with it it could mean you not having a very good day!  Like I said for the sake of a £5 fan is it worth it?

 

Is your PSU new?

[AbydosOne]

22 minutes ago, IAmAndre said:

I would like to know if I can reuse the 120mm fan that came with it

I'm pretty sure every PSU I've opened either had a non-standard fan header or had the fan leads soldered right onto the board. So unless you enjoy soldering on new leads, it's pretty useless.

(also dangerous, as noted; I'm an EE so I don't take electrical damage  "Do as I say, not as I do")

[IAmAndre]

8 minutes ago, Tomthehitman said:

Is your PSU new?

No it's not. I'm no longer using it since I installed a new one.

[mariushm]

7 minutes ago, IAmAndre said:

 

Alright good to know. Now I'm just curious, how could these capacitors injure me even with the PSU unplugged? Also I realized that this PSU was getting a bit noisier than usual and when I replaced I was barely able to touch it because there was too much static electricity. I tried everything from pressing the PC's power button to touching the case. I also noticed a lot of static electricity on the hard drives and the motherboard. I ended using the bubble wrap that came with it to take it off. Any idea why that happened?

All modern power supplies should have discharge mechanisms, which automatically discharge capacitors within a few seconds from the moment the power supply turns off, down to save levels (typically below 20-40v)

However, very rarely the psu may not have this discharge mechanism working or may not have a discharge mechanism at all, in which case those capacitors can remain charged for a long time.

 

Still, primary capacitors are typically insulated (plastic sticker on top, plastic sleeve on the capacitor) so really only way you'd zap yourself would be by touching the pins on the other side of the circuit board.

So chances are pretty small you would accidentally zap yourself.

 

Main thing... NEVER ever work on a power supply while the power cable is plugged in.

 

As for the fan, on a lot of power supplies there's no connector, the wires of the fan are soldered directly onto the circuit board, so yeah... you could open the power supply but reusing the fan would be a bit difficult, as the fan has no connector. Of course, you could buy a  molex to fan header adapter cable and cut the wires in the middle and attach the fan wires but that's an extra cost.

 

About static electricity ... it's either static electricity from you getting charged with static electricity (by rubbing socks on carpet or rubbing clothes on chair or something like that)  or it could be ac leakage from the power supply (which is intentional and safe, but if everything is right you shouldn't feel it). 

 

In case of the 2nd possibility, that could be a sign you don't have a working earthing in your outlets, or that you plug your pc or extension cord into an outlet that's not earthed/grounded properly.

Computers need to be grounded, so please check that and if you're not using grounded outlets / sockets / whatever you want to call them ... stop that

 

[IAmAndre]

29 minutes ago, mariushm said:

All modern power supplies should have discharge mechanisms, which automatically discharge capacitors within a few seconds from the moment the power supply turns off, down to save levels (typically below 20-40v)

However, very rarely the psu may not have this discharge mechanism working or may not have a discharge mechanism at all, in which case those capacitors can remain charged for a long time.

 

Still, primary capacitors are typically insulated (plastic sticker on top, plastic sleeve on the capacitor) so really only way you'd zap yourself would be by touching the pins on the other side of the circuit board.

So chances are pretty small you would accidentally zap yourself.

 

Main thing... NEVER ever work on a power supply while the power cable is plugged in.

 

As for the fan, on a lot of power supplies there's no connector, the wires of the fan are soldered directly onto the circuit board, so yeah... you could open the power supply but reusing the fan would be a bit difficult, as the fan has no connector. Of course, you could buy a  molex to fan header adapter cable and cut the wires in the middle and attach the fan wires but that's an extra cost.

 

About static electricity ... it's either static electricity from you getting charged with static electricity (by rubbing socks on carpet or rubbing clothes on chair or something like that)  or it could be ac leakage from the power supply (which is intentional and safe, but if everything is right you shouldn't feel it). 

 

In case of the 2nd possibility, that could be a sign you don't have a working earthing in your outlets, or that you plug your pc or extension cord into an outlet that's not earthed/grounded properly.

Computers need to be grounded, so please check that and if you're not using grounded outlets / sockets / whatever you want to call them ... stop that

 

That was helpful. I believe my wall outlet is grounded. I'm not sure how to check that but it has that 3rd pin. However I'm plugging the PC to a UPS, which I'm actually going to upgrade next to something more powerful.

 

I was actually wearing socks but there's no carpet in the room. And the static electricity was particularly noticeable and very unpleasant. I really thought something bad was going to happen to my components.

[artuc]

7 hours ago, mariushm said:

All modern power supplies should have discharge mechanisms

Don't rely on this.

 

I got a belt from caps on a board where it should normally discharge through the load, but there was a fault so all bets are off.

 

I know better, just had a bit of a brain fog moment.

[Guest]

7 hours ago, mariushm said:

All modern power supplies should have discharge mechanisms, which automatically discharge capacitors within a few seconds from the moment the power supply turns off, down to save levels (typically below 20-40v)

However, very rarely the psu may not have this discharge mechanism working or may not have a discharge mechanism at all, in which case those capacitors can remain charged for a long time.

 

Actually, no.  No, not at all.

 

Using a bleeder IC is only required to meet IEC 62368-1, which isn't even required until 12/20/20.

 

 

[mariushm]

1 hour ago, jonnyGURU said:

Actually, no.  No, not at all.

 

Using a bleeder IC is only required to meet IEC 62368-1, which isn't even required until 12/20/20.

 

Not talking about bleeder ics , but plain resistors in parallel with the primary capacitors  ... sometimes only connected across capacitors when relay turns off (relay that's used for the inrush current)

right now there's discharge ics used for the x2 capacitors (mains filtering) in lots of psus.

 

[mariushm]

8 hours ago, IAmAndre said:

That was helpful. I believe my wall outlet is grounded. I'm not sure how to check that but it has that 3rd pin. However I'm plugging the PC to a UPS, which I'm actually going to upgrade next to something more powerful.

 

I was actually wearing socks but there's no carpet in the room. And the static electricity was particularly noticeable and very unpleasant. I really thought something bad was going to happen to my components.

You can check it with a multimeter, preferably digital. Even a cheap 2-3$ one would be adequate for this purpose.

Set it to AC voltage, on the setting above your mains voltage (for example 750v, higher than 110v or 230v)

Put the probes on the two contacts and you should measure 110v/230v ac between those two contacts.

Remove the probes, put one probe on the earth pin and now put the other probe in each of the two contacts. One should measure 0 or a very low number, the other should measure 110v/230v ac (your mains voltage, same as between the two main contacts).

If you get get 0 or near 0 with the probe on both contacts, you don't have a working ground.

 

 

[Guest]

9 hours ago, mariushm said:

Not talking about bleeder ics , but plain resistors in parallel with the primary capacitors  ... sometimes only connected across capacitors when relay turns off (relay that's used for the inrush current)

right now there's discharge ics used for the x2 capacitors (mains filtering) in lots of psus.

 

Still not "most".

 

"Most" PSUs will have that cap charged for a very long time.  Just check the +5VSB with a multimeter after being disconnected for a few minutes.

[electropical]

3 hours ago, jonnyGURU said:

Still not "most".

 

"Most" PSUs will have that cap charged for a very long time.  Just check the +5VSB with a multimeter after being disconnected for a few minutes.

I've heard that one way of discharging the caps after the PSU has been unplugged from the wall is to press the start button on the case as if we were trying to turn the computer on ; The fans start rotating and then stop, which presumably indicates that the caps inside the PSU are now fully discharged, allowing the user to safely manipulate the PSU ;

Is that correct?

[Guest]

56 minutes ago, electropical1412 said:

I've heard that one way of discharging the caps after the PSU has been unplugged from the wall is to press the start button on the case as if we were trying to turn the computer on ; The fans start rotating and then stop, which presumably indicates that the caps inside the PSU are now fully discharged, allowing the user to safely manipulate the PSU ;

Is that correct?

No.  Because the power good signal would not be live so the motherboard wouldn't do anything.

 

Best thing is to just put a load on the +5VSB when the PSU is unplugged.