PDA

View Full Version : Electolytic Capacitors



B.M.
09-11-2009, 07:52 PM
I'm trying to repair a very old Motherboard with three "Popped" capacitors and cant find anyone who stocks them. (Jaycars & Dick Smith can't help)

I need two 1000uF 6.3 volt and 1 1500uF also 6.3 volt.

I don't think the voltage matters unless it is less than 6.3 volt.

Any suggestions who might stock these? :thanks

decibel
09-11-2009, 08:44 PM
I (Jaycars & Dick Smith can't help)



?? just found some 16 volt ones on the Jaycar website.

Speedy Gonzales
09-11-2009, 08:49 PM
Did you ring or go to their site?

Terry Porritt
09-11-2009, 09:34 PM
Jaycar have low ESR capacitors, the nearest are 1000uF 10v and 2200Uf 10v

CAT. NO. RE6304. CAT. NO. RE6306

Just type low esr capacitors into the keyword search box.

rbland
09-11-2009, 10:54 PM
Another option would be to buy from RS Components, they do free shipping and have insane amounts of electronic components.

You have to be careful soldering and de-soldering mobos as they can have multi-layers.
I have done a few before, all went well.
Try get low ESR capacitors, I didn't use low ESR and it still worked fine.
Capacitors can be any voltage, just as long as they are greater than 6.3V

RS Components: http://newzealand.rs-online.com/web/

B.M.
10-11-2009, 12:44 PM
Thanks guys, RS have exactly what I want and will dispatch same day if paid for by Credit Card so that seems fine. :thumbs:

As a matter of interest, just how accurate do the values on these capacitors have to be? :confused:

I mean can you replace a 1500uF capacitor with a 2200uF and expect everything to work as it should? Ok, I realise that in a lot of cases the manufactures have a tolerance of 20% but Iím just curious as to how far one can expect to push the envelope before one creates further problems. :cool:

sammo450
10-11-2009, 01:58 PM
I'm pretty sure using different values to the original would be a very bad idea. Greater capacitance allows for greater charge, and therefore greater current supplied/longer discharge time.

zqwerty
10-11-2009, 04:42 PM
2200uF instead of 1500uF will be fine. Mostly it is a physical size problem, mount on stalks if you have to, things are not super-critical on this type of p/s generally speaking.

Billy T
10-11-2009, 06:46 PM
Higher values are no problem, just don't go beyond 50-75% increase because inrush currents could be an issue. Voltage ratings above the original are fine as well, but again, don't go too high or they may not form properly. Do get low ESR types though, filtering will be seriously degraded if you don't, and you may get random glitches.

Cheers

Billy 8-{)

dannydesil
10-11-2009, 10:47 PM
I'm doing a 12V->48V converter at 330W. Even with a four phase converter,
the ripple current (according to LTspice) is about 7A rms. I need about
1,000uF (63V will be okay) and the max ambient will be 60C.

The caps I've looked at from Panasonic and Nichicon can handle about 2A max
of ripple current (at 100KHz).

What worries me is if I parallel a bunch of them, and especially if I allow
multiple suppliers for the caps, I'll never be sure how the ripple current
is shared between them. So, do I put ten in parallel to be sure
(rhetorical)?

What would be nice is to find ONE cap that can do all the ripple current.
Anyone know of such a beast?

Thanks.


[Mods comment: is not a genuine question - it is a direct copy from another forum. This person has been banned as they are a known spammer who is using the same posting technique here on many other forums - Jen]

zqwerty
10-11-2009, 11:27 PM
It is better to use multiple caps than use only one big one (heating spread over a bigger surface area, also redundancy) also put more than a few .01uF and .1 uF ceramic caps along the power supply tracks to neg and one in parallel with each of the big caps (electros tend to be inductive at high freqs).

Paul.Cov
11-11-2009, 10:27 AM
I've used the Jaycar 2200uF 10V and 1000uF 10v without any drama as substitutes for the caps you've mentioned.

Actually, there was drama - getting the darn things into place! It can be an art! Good luck.

Agent_24
15-01-2010, 05:10 PM
Another option would be to buy from RS Components, they do free shipping and have insane amounts of electronic components.

RS Components: http://newzealand.rs-online.com/web/

That's where I get mine from, and they stock much better quality brands than anywhere else, and pretty cheap too!

zqwerty
15-01-2010, 08:34 PM
In another life-time I used to be the sales rep for RS Components in Ndola, Zambia as part of my job at C.M.B Engineering. I traveled around the Copperbelt selling engineering parts to mining engineers. My favourite part was Toshiba High Voltage Vacuum Contactors which were worth $3300 each, nice commission.

I also used to represent Crabtree, Stone Stamcor, Wolf Portable tools and many others which I can't remember the names of anymore but they were well known.