Capcitor voltage question

[Prowler]

Hello everyone this has been a great site!!

I work at a retail computer store and have been dealing with faulty cap'd boards for several years.

The question I have is about capacitors themselves. The voltage written on the cap itself, is it a maximum or a running voltage? I guess or other?

Main reason I am asking is I have an old PC CHIPS board, but it has 1 blown cap on it (I guess for now). So i wanted to experiment on it.

Can I replace it will a higher voltage cap say 16 volt off another board I know is dead?

Also does this site sell individual Caps? I have a power supply by Aspire/Turbo that developed one, I believe it is hindering my 12V rating.

Wayne

[Rainbow]

Re: Capcitor voltage question

That's maximum voltage which should be never be exceeded or even reached.

[willawake]

Re: Capcitor voltage question

the voltage on the cap is the rated voltage, it is a maximum value. Do not use replacement caps with less voltage. It is ok to use more voltage and more capacitance than the caps already on the board.

it is not recommended to use old caps. you dont know the condition of them. also it is more difficult to work with them because of the small length of the leads.

i guess Topcat will sell you one cap but its gonna make that cap expensive because of the shipping cost. better to buy a whole kit. anyway pm him from the forum.

[Prowler]

Re: Capcitor voltage question

Thanks guys that is great info.

Diameter? does it matter as well?

Can't believe how many boards have come back to our shop with blown caps.

Some people have been amazed with my ability to find them. basically I check any board that comes in with integrated sound that had a joystick port.

[PeteS in CA]

Re: Capcitor voltage question

The voltage on the can is its maximum voltage for continuous operation. IOW, don't use a 10V cap on the +12V rail. However, if you look at the cap specs, you'll see that there is a higher "Surge Voltage" rating, possibly with the duration and frequency of the surges specified. Think of that as a "don't go there rating". In the world of mil-spec components, it used to be (may still be) that the US military required that caps be operated at </= 50% of the rated voltage.

Diameter and Height are usually just a mechanical fit issues. However, shorter, larger diameter caps are often slightly higher impedance than taller, smaller diameter caps of the same series, capacitance, and voltage rating.

[willawake]

Re: Capcitor voltage question

it is very difficult to find replacement caps at the same sizes as originally on the board. I know Topcat does his best to supply the best width replacements.

for instance i source my caps from a european mail order company so if i was looking to replace a 1000uf 6.3v that was 8mm width i would only be able to order one at 10mm width. when you have two caps close together or a row of caps you have to angle some of the new caps to get it all to fit. looks bad but works fine. same problem with height sometimes, so you can bend the leads and lay caps lying down if they will interfere with the pci or agp cards etc.

i dont see what at all integrated sound has to do with bad caps. any board is a candidate for badcaps

[Prowler]

Re: Capcitor voltage question

Integrated sound cards were an indication of the age of the motherboard. Most newer motherboards don't come with a joystick port integrated, it is often a header connection.

PeteS in CA & willawake thank you both for the info. It is very helpful. I'll have to look in to how much it is for a kit to be shippe to Canada.

[PeteS in CA]

Re: Capcitor voltage question

Look into Digi-Key and Newark Electronics, Prowler. They should be able to ship to Canada, and may have warehouses there, too. Future Electronics is a Distie that is based in Canada, possibly near you, but I don't know what their minimum quantities, if any, might be. Digi-Key sells Nichicon and Panasonic. Other posters have mentioned buying UCC from Newark. Future sells Rubycon, Nichicon, and Panasonic, IIRC.

Given the age of the MB, you probably have a cap exhibiting end-of-life wear-out. Chances are, that same value-voltage part may be in a smaller case size now.

[Prowler]

Re: Capcitor voltage question

on Digi-key's website, I can't find anything 3300uf 6.3V 10mm Diameter, 5 mm post difference?

Is there any there that are recommended? I notice most of the are 12.5 diameter.

Any suggestions?

Wayne

[linuxguru]

Re: Capcitor voltage question

It depends - check the layout of the caps on the motherboard. You can sometimes substitute a 12.5mm in place of a 10mm, but the leads may need to be bent and it may not sit flush on the
motherboard.