Zyxel PSU

[diif]

Obvious why this switch has failed !
Should I be replacing with a DC or AC cap ?
I have a choice of three is it's a DC cap. Which one would you buy ?

http://uk.rs-online.com/web/p/alumin...itors/7152303/

http://uk.rs-online.com/web/p/alumin...itors/7260729/

http://uk.rs-online.com/web/p/alumin...itors/6997559/

Thanks

[eccerr0r]

Re: Zyxel PSU

Pics or it's not broken...

[999999999]

Re: Zyxel PSU

1) I am assuming you have a zyxel network switch that stopped working because the power supply for it failed.

Any of those 3 capacitors you linked should work, but I wouldn't get the Rubycon because it's excessively priced. It does not need to be an AC capacitor as it is rectified to DC by one or more diodes before that capacitor in the circuit,but this should be obvious by looking at the original capacitor, looking up how it is rated.

[diif]

Re: Zyxel PSU

Ahhh, missing photos, seems the uploading failed last night.
Here we go.

I bought a lot of 10 faulty assorted gigabit switches. I have Netgear, HP, Dell and a lovely Belkin.
Obvious failures in most of the power supplies although one of the small Netgear switches is down to a damaged DC socket.

Thanks 999999999 i ordered the Panasonic.

[Per Hansson]

Re: Zyxel PSU

[goodpsusearch]

Re: Zyxel PSU

L O L

[diif]

Re: Zyxel PSU

Haha, liking that.

[eccerr0r]

Re: Zyxel PSU

Bipolar/AC capacitors should say "BP" on them or look like they're completely symmetric minus having possibly a dot on which pin is the outside foil. If there's a band of any kind it's a unipolar DC capacitor.
I don't know if there are any recent usage for bipolar electrolytic these days - perhaps other than audio crossovers and even then people probably prefer some other method for separation. Induction motor AC caps aren't electrolytic - and bipolar electrolytic capacitor ESR is not that great... if not outright bad...

Oddly enough I've never tested the ESR on a bipolar cap, I'd think these would be pretty bad?

[diif]

Re: Zyxel PSU

Cheers eccerr0r.

I'm hoping the parts will be here later today, i'll update one i've fitted it.

[eccerr0r]

Re: Zyxel PSU

Hmm... I have a ~70KHz analog ESR meter that measures (NOS unless indicated):
Nichicon 2.2uF/50V BP 2 ohms
Illinois Cap 22uF 35V BPRM 0.5 ohms
Symphony Asuno 2.2uF/50V NP 2.5 ohms (hey... that Nichicon is better!)
Matsushita 33uF 16V BP Y 1 ohm (PULL)
Matsushita 33uF 16V BP Y 0.8 ohm (PULL)
CapXon 1uF 250V NP ~6 ohms (PULL)
Richey 16uF 50V ~0.4 ohms (PULL)

Hmm some of them are comparable to small polarized caps after all. I thought these bipolar caps are usually made by putting two polar caps in inverse-series which means ESR will be doubled...

[stj]

Re: Zyxel PSU

i notice the capxon is worst - what a surprise.

bipolars are usually a lot larger than a polarised equiv cap though.

[momaka]

Re: Zyxel PSU

https://www.badcaps.net/forum/attach...1&d=1444998619

That picture just made my day!

And maybe NASA should put some CapXon caps in their thrusters to get an extra "boost" at liftoff .

[diif]

Re: Zyxel PSU

Just to update, replaced the cap and the bridge rectifier and the switch is back to working.

[eccerr0r]

Re: Zyxel PSU

i notice the capxon is worst - what a surprise.

bipolars are usually a lot larger than a polarised equiv cap though.

Also note the worst one is also only 1uF (due to my ~70KHz meter, it may make a difference), and also highest voltage (250V) so the ESR might be a bit higher for this one just because...