Did I get a dud primary cap?

[Pentium4]

This is a Panny cap I got from Digi Key, I know it's within the 20% margin but it seems pretty low and the ESR seems a little on the high side too. It's going into an OCZGXS700

[mariushm]

Re: Did I get a dud primary cap?

I don't think you got a dud.

It's probably a consequence of how the capacitance checking is performed, the voltage used is probably very low, and since it's a 450v rated capacitor...

[Behemot]

Re: Did I get a dud primary cap?

It's actually 400 V only. Is it safe for active PFC? I usually see 450 V lately as the boost can go to as much as 400 V.

[Pentium4]

Re: Did I get a dud primary cap?

It's possible because the one that failed was a CapXon with the same value, although it's hard to say cause it's CapXon

[mariushm]

Re: Did I get a dud primary cap?

My bad, I wasn't paying much attention. 400, 450... not much difference, the point is that these meters use 0.2v or somewhere around that value to send pulses into the cap and measure how fast they discharge or something like that, to determine the capacity value. Sorry for not being more accurate with explanations.. I'm messed up, just arrived here to my place after visiting my parents so I'm all tired from the train ride and cold weather.

With a capacitor rated for such high voltage, it's possible that they get a wrong capacitance value.

Do a test if you want with some 2.2 - 10uF 400-450v capacitors and you'll see they should be overestimated, the meter will say they have more capacity than what they actually have.

I've tested my esrmicro against the Uni-t UT61E which if I remember correctly uses about 0.5v pulses and gets closer to the real value imho.

[retiredcaps]

Re: Did I get a dud primary cap?

This is a Panny cap I got from Digi Key, I know it's within the 20% margin but it seems pretty low and the ESR seems a little on the high side too.

I have only measured a handful of large filter caps all in circuit on my Fluke multimeter and all have measured lower than the stated value, but within the 20% value.

[ben7]

Re: Did I get a dud primary cap?

Might have also just sat a while, maybe is just needs a good re-forming

[Pentium4]

Re: Did I get a dud primary cap?

Thanks for the replies, I'm sure it will be fine! I can just be paranoid sometimes

[ben7]

Re: Did I get a dud primary cap?

Thanks for the replies, I'm sure it will be fine! I can just be paranoid sometimes

Actually, the TS-UQ series datasheet says that the 470uf - 400v caps have an esr of:
120Hz - 0.423 ohm
20kHz - 0.212 ohm

So, again, its probably OK. The TS-UQ series isn't supposed to be ultra-low esr either.