Replacing two capacitors.

[sandrogalli]

Hi there,

I'm new too this board and have never replaced a capacitor before. Basically, two capacitors on my Asus P4S800-mx seem to have blown not because of a design flaw but i think because of a power-supply failure (caused by impact). The tops of the two capacitors in question have caved in and there is a brown residue around the top.

The capacitors are marked with 'KZG' so I assume they are the Chemicon KZG's I have seen referred to in this site. They are rated with 820uf and 6.3v. From what I understand, I need to replace these capacitors with a similar or higher voltage, but I was wondering if I could have a little more advice. Online I have found some 2000uf, 6.3v KZG's; would these be a good choice for a replacement? Also would I be correct in assuming that these capacitors would be larger in size? (I dont think this would be a problem as there is plenty of space for the capacitors, so long as the distance between the 'legs' is the same).

Alternatively, I have found some unamed 1000uf, 6.3v capacitors on ebay that appear closer in size and rating, although I have no guarantee these capacitors are from a reputable brand. Someone here may be able to identify them though so here is the picture:



Ok, thats it I think just need some advice on whether to choose go for a similar brand or rating of the ones already on the board, sorry for the long post and thanks in advance for any replies,

san

[willawake]

Re: Replacing two capacitors.



here's a chemicon KZG

the 820uf is 8mm diameter, the 2200uf will be 10mm

no idea what those ebay caps are, why not ask the vendor.

check this link for what caps to buy. the better ones are to the right of each line.
https://www.badcaps.net/forum/showthread.php?t=2280

[gonzo0815]

Re: Replacing two capacitors.

KZG are Ultra low ESR caps, i doubth that any other brand then Rubycon, Panasonic and the other known good brands can reach similar specs. Therefore i would certainely not use any other brand.

[Sir_Loin]

Re: Replacing two capacitors.

I find myself in a similar position. I've actually replaced caps a few times, but I've always had some dead boards to use as spare parts. I've got to go out and buy four for the wifes computer tomorrow.

The question I think sandrogalli wanted answered (and mine) is "ultimately, do you try to match capacitance and go with the same or higher voltage, or try to match the voltage and go with a similar or higher capacitance?" Is there anything to be gained increasing either?

I may be wrong, but my logic tells me to match capacitance and go with the same or higher voltage. My reasoning is if the capacitor is rated significantly higher (voltage) it should last longer. For example, if you use a 130v light bulb on a 120v circuit it will last longer.

OK fellas, hand the cap newbie his ass......

Loin

[Topcat]

Re: Replacing two capacitors.

OK fellas, hand the cap newbie his ass......

Loin

Before we can accept you, you must fold for the badcaps.net folding team.

j/k

It depends on the circuit to answer that question. Slight variences in capacitance typically won't have any adverse affests. NEVER decrease the voltage unless you're sure of the max voltage that will be on the cap's position, and of course never put a lesser volt rated cap in its place. For the sake of experimentation, modding capacitance values can be an interesting (and fun venture), but thats more of a trial and error venture....

[Sir_Loin]

Re: Replacing two capacitors.

Awww mannnn. It's all for the good of humanity. I may consider it though

I've got 4 x 16v 1500uF that need to be replaced. I was thinking of going with some 25v 1500uF since Prescotts are power hungry puppies.

[Sir_Loin]

Re: Replacing two capacitors.

modding capacitance values can be an interesting (and fun venture), but thats more of a trial and error venture....

So, Higher voltage and same capacitance should be fine, right?

[Topcat]

Re: Replacing two capacitors.

So, Higher voltage and same capacitance should be fine, right?

yes. it's unneeded though. The most voltage that'll be on those 16v caps will be 12v. They're filters off the 12V rail. Increasing the voltage will not help (or hinder) anything.

[Sir_Loin]

Re: Replacing two capacitors.

yes. it's unneeded though. The most voltage that'll be on those 16v caps will be 12v. They're filters off the 12V rail. Increasing the voltage will not help (or hinder) anything.

That's exactly what I needed to know. I figured the 16v was the manufacturers effort to put in something slightly overrated. Thanks.

Loin

[gonzo0815]

Re: Replacing two capacitors.

Choose the caps by their ESR valuies, this is in any motherboard circuit the absolute most important factor. The rule is the lower the better. Higher voltage won`t hurt, but you probably gain nothing. If you realy have some money to spend, take some Oscon or similar solid polymer caps, but they are realy expensive. But on p4 boards there is probably nothing better than this. Especially those 820uF caps are IMHO to small to stand the high ripple currents generated by those Intel monsters. Many of those boards are ex factory equiped with oscons and probably the desing of this board intended their use.

In any other cases i suggest some good Rubycon MCZ or the equivalent series from the other major brands. For those 16v input caps you probably can use any LOW ESR series from the recomended brands. In no way you should use some generic or odd brand or not LOW esr types. They are absolut not suited. The capacitance is not criticall, but usually i would not lower it, only go higher, but not to mutch. E.g. not more than the double value, may be a little lesser is better. Instead of 1500uf there is probably no problem using 1800uF, but 3300uF could be to mutch.

[Sir_Loin]

Re: Replacing two capacitors.

Choose the caps by their ESR valuies, this is in any motherboard circuit the absolute most important factor. The rule is the lower the better. Higher voltage won`t hurt, but you probably gain nothing. If you realy have some money to spend, take some Oscon or similar solid polymer caps, but they are realy expensive. But on p4 boards there is probably nothing better than this. Especially those 820uF caps are IMHO to small to stand the high ripple currents generated by those Intel monsters. Many of those boards are ex factory equiped with oscons and probably the desing of this board intended their use.

In any other cases i suggest some good Rubycon MCZ or the equivalent series from the other major brands. For those 16v input caps you probably can use any LOW ESR series from the recomended brands. In no way you should use some generic or odd brand or not LOW esr types. They are absolut not suited. The capacitance is not criticall, but usually i would not lower it, only go higher, but not to mutch. E.g. not more than the double value, may be a little lesser is better. Instead of 1500uf there is probably no problem using 1800uF, but 3300uF could be to mutch.

Thanks for the advise. What does esr stand for? Acronyms can be a pita for the poor bastard who isn't in that particular field I'm guessing electrostatic resistance?

I had a hard time finding a place that actually stocks capacitors in Houston. I ended up getting some Nichicon HE(M). They had H0534 and 105 degree on them. They seemed to be the best of the lot, so I grabbed the last 4. I only replaced the ones for the 12v line which were 16v 1500uF. I must be getting better at this because I didn't have a lot of trouble getting the bad caps out and clearing the holes. Overall, it came out extremely clean, and the best thing is my wifey is happy again

I'm just going to order an assortment from one of your recommended online vendors so I'll have the most common caps in case I need them in a pinch...again.

[Topcat]

Re: Replacing two capacitors.

Equivalent Series Resistance

[yanz]

Re: Replacing two capacitors.

What does ripple current mean?
https://www.badcaps.net/forum/showthread.php?t=1458

[PeteS in CA]

Re: Replacing two capacitors.

The AC current through the capacitor due to charging and discharging. Since Power = current squared X Resistance, P(capacitor)=[I(Ripple)^2](ESR). Power dissipated in the cap heats up the cap from the inside.

[gonzo0815]

Re: Replacing two capacitors.

Well it is easiy to immagine, the input voltage to the caps is an squarewave, during the on time the cap is charged, thus ther is some current flowing into it. depending on the dutycycle the capazitor discharges during the offtime. Thus some current will flow out of the cap. The current has to flow through the whole cap, the whole foil and leads wich is the ESR. At reaonable high frequency thi s could be seen as AC ripple current.