polymer caps for psu?

[uligli]

Hi guys, here's a electronic newbie question: can we use polymer caps for a pc psu?

[370forlife]

Re: polymer caps for psu?

Short answer: no

It's hard to find polymer caps over 1000uf, with the decreased uf, the rails loose the umpf, or think of it as a truck, the uf as it's weight. When a large, sudden load increase comes along, such as the truck hitting a car, the truck is going to slow down more the less it weights. Basically, the less the uf rating, the lower the voltages may drop when confronted with a larger load. The drop would be so quick a multimeter wouldn't pick it up either.

The very low ESR of polymer caps can also make ripple worse, as the pi filters are "tuned" to the certain esr of the caps used originally. Lowering (or raising) this ESR can cause the ripple to increase.

There are some new psu's with polymers in them, they use them on the dc-dc daughter boards that generate the 5v and 3.3v from the 12v. They also use standard electrolytics, with some polymers thrown in on modular pcb's or after the pi filters as supplementary. Don't know if they really do anything, or if they just are more of a marketing gimmick.

[goodpsusearch]

Re: polymer caps for psu?

"the pi filters are "tuned" to the certain esr of the caps used originally."

Is that certain? That means that when recapping one should try to find same esr replacement caps and not lower esr ones?

And if the new caps have a bit lower esr than the original is that a problem?

[370forlife]

Re: polymer caps for psu?

"the pi filters are "tuned" to the certain esr of the caps used originally."

Is that certain? That means that when recapping one should try to find same esr replacement caps and not lower esr ones?

And if the new caps have a bit lower esr than the original is that a problem?

You want to try to stay as close as possible to the original ESR. If the psu is known to have a problem with ripple, you really need to stay close to the original ESR, but if it is a power supply known to have good ripple, putting something like rubycon MBZ in it may still be in spec but still raise the ripple.

[uligli]

Re: polymer caps for psu?

There are some new psu's with polymers in them, they use them on the dc-dc daughter boards that generate the 5v and 3.3v from the 12v. They also use standard electrolytics, with some polymers thrown in on modular pcb's or after the pi filters as supplementary. Don't know if they really do anything, or if they just are more of a marketing gimmick.

Enermax modu87 PSUs Many sites recommend them

[370forlife]

Re: polymer caps for psu?

CWT and Superflower loves them too. I think superflower was one of the first to start doing it. Won't be surprised to see it in low watt psu's soon with the efficiency craze.