is it OK to replace caps in a PSU

[moho]

i just got a antec 480W, popped her open and seen a few caps bulging. I am pretty sure its not a good thing to use it while the caps are going out. Is it OK to replace them? i heard and read that some caps have deadly voltage in them..very hesitant to do it at this point. it thinking wether or not to just chuck the unit altogether.

[Oklahoma Wolf]

Yes, in fact I'm doing just that with three Channel Well PSU's (OEM for Antec) as soon as the caps arrive from Digikey. However, many of them will be oddball values and/or sizes... you'll have to pick acceptable substitutes. Badcaps.net has a very good forum for this sort of thing.

My suggestion would be to replace everything on the secondary side over about 470uf - I've learned with these CWT units that where one bulges, others will soon follow. The huge primary side caps will likely be fine - no need to do them.

[SolidxSnake]

if you can find correct capacitors. I'd fully discharge the PSU before opening it up in the first place. To discharge it, i'd first keep it plugged into my computer. I'd then turn off my computer normally, and pull out the power plug (if the PSU has a switch). then i'd hit the power button of my computer once (the computer turns on for a split second or two, and then dies down becase the PSU can't supply the power), and keep hitting the power button for maybe 10-20 times. i'd know it's drained by then.

if the PSU doesn't have a switch, i'd probably plug it into a wall, turn te computer on, and get it idling or something. then pull the power plug. after it dies out, i'd short the green and black pins of the ATX connector with it still plugged into the mobo to fully drain it.

[techun]

dont you also discharge the caps with an insulated screw driver? or is that basically accomplished by turning the comp on with it unplugged

[moho]

dont you also discharge the caps with an insulated screw driver? or is that basically accomplished by turning the comp on with it unplugged
yeah im also wondering if theres any way to discharge it without having it connected to a comp. as the cables are all cut and it will be very hard to connect it currently.

[princeofdarknes]

short the green wire to any black wire with the switch turned on (if it has one) and it unplugged, that's basically what turning on the computer does, so it discharges it

[zeimbo]

dude, buy a new psu. they can be had relatively cheap and youll safe yourself the hassle of possibly owning yourself with voltage

[Skeith]

Replacing caps is easy. Remove the unit. Unplug it. use a screwdirver to bridge the two terminals on the caps. *spark* there its discharged. Repeat for all caps. Work till your hearts content. lol I never discharge caps. Been shoked a few times. Also been shocked from a 700Volt cap in a tube amp. lol that one was nasty.

[moho]

dude, buy a new psu. they can be had relatively cheap and youll safe yourself the hassle of possibly owning yourself with voltage
Just trying to fix up a $20 PSU :)

Ill try replacing the caps...

[zeimbo]

well, you better hope your medical insurance covers idiocy :). good luck tho, take it to radio shack and see what they say.

[Cyrix_2k]

The PSU should self discharge. However, I'd short the caps out with a BFSD (Big F***ing Screwdriver) just in case. Other than that, if the caps are filtering caps, and if they're big, they probably are, any voltage value he same or higher than what is present should be fine and you *should* be able to fudge the capacitance values some too. If you don't know what role the caps are playing, play it safe and just replace the caps with caps of the same capacitance rating and of an equal or higher volatage rating. Also, make sure the caps you choose will fit before ordering!

[Cyrix_2k]

One last thing, when working on the PSU, keep one arm behind your back so if you do f'up, you won't kill yourself.

[zeimbo]

One last thing, when working on the PSU, keep one arm behind your back so if you do f'up, you won't kill yourself.

i dont get it..?

[moho]

One last thing, when working on the PSU, keep one arm behind your back so if you do f'up, you won't kill yourself.
maybe while holding a grounded cable :p

[Mandachuva]

IMHO, you only need to be changing the output caps (those near the output wires -> the ones going to the mobo, HHD...), and you can use ones with slightly bigger capacitance, no trouble at all. BUT you need to make sure they are of the same or larger maximum voltage (the value written on them - they should be something like 16V for the 12V output, 6V for the 5V, and so on), otherwise they'll go POOF. Also, make SURE you use low impedance, low ESR caps - such as the Yageo SX.

And never mind the warnings, if the PSU is unplugged (and it REALLY should be), you won't get a discharge, and if you do, you MAY get a really small one - I'm very prone to such things, and I've opened my PSU a dozen times without discharging it first, with no trouble. In a few seconds after powerdown, it's all discharged - theoretically. All the caps inside are small (<1500uF), so there's not much to get discharged, either.

If you open your PSU, you should also check the underside of the PCB for signs of scorching. In cheapo PSU, and especially does made by Deer (the name is stamped on the the PCB, near the big input caps) there are a couple of very small resistors in the middle of the PCB - inbetween the fan and the second heatsink (the one closer to the output wires), which are to small a wattage, usually poorly ventilated, and usually burn up the PCB. If this is the case, maybe you should consider changing them with larger wattage, same resistance resistors.

And again, to counter the numerous "You'll get shocked!!!" warnings, as long as you unplug the PSU, believe me, you won't! :santa:

Some more. I've read/heard quite a lot about bad output caps on the Antec PSU, and my guess is maybe because of poor ventilation - the caps heat up, they dry up, and start failing - bulging. Maybe you should (as I did :)) drill a few small holes (not very tall ones), near the output caps, on the side of the PSU, to achieve better ventilation in that area. Also, if you change them, feel free to seat them not directly to the PCB, but a little higher (1-1.5 cm above the PCB), and use a (don't know if you understand) hot silicone gun (sorry, I'm Romanian, no idea how it's actually called) to "glue" them to the other components, so they stay in place. This should achieve better ventilation, alas longer lifetime.

[Cyrix_2k]

maybe while holding a grounded cable :p
bad idea. The idea is to keep you from being able to create a path between your arms. This will prevent electricity from hitting your heart if you were to get shocked.

[moho]

bad idea. The idea is to keep you from being able to create a path between your arms. This will prevent electricity from hitting your heart if you were to get shocked.
Ahh i see, i didnt understand you at first.

[Nano2e]

It's just fine....unplug the psu, pull it out. Short the green wire to any black one using a bleed resistor (a large one like 100Kohm). You shouldn't have to wait too long but if you want to feel safe go ahead and leave it for a while. It's not going anywhere. After the caps are discharged you can replace them with a cap of the same farad rating and a higher or equal voltage rating.

[larrymoencurly]

dude, buy a new psu. they can be had relatively cheap and youll safe yourself the hassle of possibly owning yourself with voltageBut a 480W Antec repaired with all Japanese brand caps should last forever.

The recommendation to unplug the AC cord while the computer is still running should discharge all the caps almost completely, but even if it doesn't, the only danger is with the high voltage caps. However Antecs have bleeder resistors that will discharge them completely in 30 minutes. OTOH my Enermax EG365P-VD has no such bleeders and retains enough charge to blip the case power light even with the AC cord unplugged, even overnight.

Good luck finding capacitors narrow enough to fit in the Antec because some of the higher capacitance values are hard to find in the 10mm diameter size that Antec typically uses.