Modding a PSU with a new fan?

[Big.Wayne]

Hello,

I've got a few old ANTEC 350w PSU's that are working fine but the fan is starting to make a racket and I wondered whats involved in swapping out the old fan for a nice new one?

I remember several years ago trying this but found the included 80mm fan had a funny non-standard header so I couldn't simply unplug it and install the new one.

These PSU's are three-four years old so I'm not too worried about voiding the warranty by opening them up but I just wanted to hear any tips or feedback from somebody else that has done similar?

Also how dangerous is an unplugged PSU? I don't want to blow myself up either!

I am going on a two week break soon so if I leave them on a shelf unplugged will that drain them and make it a bit safer to work?

Thanks in advance

 

[OpenToSuggestions]

It is dangerous opening up a psu. I am not electronics expert but I bet there is something in there that could zap you
As some of the outputs on a psu are 5v and 12v that means some high currents are going to be there in order to provide the power.

It isnt worth the risk tbh.

 

[manic_man]

Modding PSU fans is an easy task Only downfalls come about if a) the header is non standard (as you have found) or b) its soldered to the PCB. Both can be overcome, depnding how competent you are with these things. A non standard header can almost certainly be re-used to re-wire a new fan, just make sure piositive goes to positive and negative goes to negative

With re: to the danger of PSU's. Well sure the large caps hold a lot of charge and indeed can hold it for upwards of 8 or so hours after it has been swithed off. However if you a) pres the power button on your pc after you have unplugged the kettle lead (light might flicker on) and then b) leave them for an hour or so and c) don't touch any caps or coils, you'll be fine
if in doubt, just make sure you only prod around in there using insulated tools.

Be aware also that some PSU's automatically control the voltage offered to the fan depending on temp. If that is the case, find out the operating voltages of the PSU and make sure that the fan you give it can be used with the lowest voltage the PSU supplies via the header (normally they dont go below 7v and 99.9% of fans will be fine with this).

Do it though Good way to get into the whole fan replacement malarky, I warn ya though its addictive making a quiet pc! And expensive!

 

[Big.Wayne]

It isnt worth the risk tbh.

No pian no gain as they say!

Do it though Good way to get into the whole fan replacement malarky

Thanks for the feedback!

I warn ya though its addictive making a quiet pc! And expensive!

No worries, I been into quiet PCs for years but I am trying to avoid the expense of new PSU's when working on el-cheapo builds using reclaimed parts, I know plenty of people running older Pentium3, Pentium 4 and AthlonXP systems who don't have a lot of spare cash and would really benefit from the quiet computing enviroment, some of these machines are so noisy it can bring tears to your eyes!

So if I can bring ear-bliss by modding in the quiet fan its something I will do. I guess I will have to get myself a little solder kit and sus out how to splice wires in the PSU's with non-standard or soldered headers.

So one last thing, if I leave the PSU unplugged for two weeks it should be pretty safe right?

 

[semi-pro waster]

So one last thing, if I leave the PSU unplugged for two weeks it should be pretty safe right?

Should be, I'd take the quick first step that manic_man suggests of turning the system on with the PSU attached but not plugged in as that should discharge most of the electricity stored pretty quickly.

Try not to touch any of the caps directly if you can avoid it, after that length of time it shouldn't matter but there is always the risk of damaging them as well even if you aren't going to be damaging yourself.

 

[Big.Wayne]

Ok thanks, yes I already do that power cycling thing to drain the extra charge but I wasn't sure if that really did get rid of 99% of the charge.

What I didn't consider is that the PSU may regulates the fan speed, not sure how to find out if this happens or not on the PSUs I have, I'm sure not all PSUs did this?

That does indeed complicate things further, if I buy a quiet fan it may be really feeble if the PSU gives it just 7v to run, or If I buy a stronger RPMs fan thinking the PSU will reduce its speed and it doesn't I'm gonna still have noisy PSU's lol!

What do you reckon?

 

[semi-pro waster]

It's a bit of a toss up but I'll guess on the side of go with the higher RPM fan but try and pick one that is noted for quiet anyway just in case. Talk about hedging your bets.

It might make it more complicated but if the PSU doesn't limit fan speed automatically could you wire in a resistor of some sort to lower the voltage?

 

[Nick644622]

3-4 year old, it is on borrowed time, I wouldn't spend much time or cash on moddng one. I have one in an old PC, it runs warm when the PC is idling, I'd be wary of fitting anything that moves less air.

 

[Big.Wayne]

could you wire in a resistor of some sort to lower the voltage?

haha, I can undo 1000 screws take something apart and then put it all back together again but can I wire in a resistor? No I don't think so, at least its not something I've done before but I do want to step up my game a bit so. . . .

Think what I will do it look up the spec of the branded ANTEC PSU and see if it controls the rpm, that would be the logical step.

3-4 year old, it is on borrowed time, I wouldn't spend much time or cash on moddng one

Hmmm,

Well its been lightly used and according to my LCD power tester its all good, strong rails and PG signal etc so I thought it would probably be worth revamping? I mean a couple of fans is gonna cost a tenner so I thought it would be worth a punt.

 

[Nick644622]

I hate throwing working stuff out too. Agreed if you need one & already have one it is a tenner well spent on a fan & the early Antecs didn't explode as often as the ones from 18 months or so ago. When I said warm I may have understated. I think it really needs a good airflow going on, not a dribble. Compared to a modern PSU with 80% efficiency I'd say it runs hot with the PC at idle. More heat = more power being wasted, knock a tenner of the cost of a new PSU, knock off the wasted electricity it is going to use, if you get my drift ?

 

[BlackBat]

I used to be repair P.C.'s, V.D.U's, monitors, printers, etc. for a living. Obviously disconnect the P.S.U. from the mains first before doing anything, as far as non-standard headers go you could solder directly to the board (if you have tools).
The only thing I would watch out for is the capacitors, once in a printer P.S.U. I had a faulty resistor which meant the capacitors didn't discharge. Please bear in mind that the machine in question was faulty, once repaired (replaced resistor) there was no such problem (as there shouldn't be).

 

[NoobieOCer]

nah PSU are safe just stick ** finger in it XD just joking if you JUST unplugged it don't touch no caps, let it discharge for about 10 mins and then its safe as long as the mains cable is out when it was discharging erm as for the fan just cut the wire up and patch it up with some wire tape and then screw it on, if wont fit just super glue it on or use cable tires.

and 2 weeks is too much really i leave it alone for 10 mins and i touch it you might get a littel shock but nothing that can harm you, you can try it fun my hand felt really funny when i got shocked

 

[IAmATeaf]

Should be easy, open her up, avoid touching anything you don't need to. Then snip the wires off the old fan, solder and heatshrink the new fan in, job done. You could also as somebody has suggested just snip the wires and use the smallest terminal block to reconnect either ends of the wire.