Polymodding Asus A7V266-E, Capacitor Recommendations?

[gryffinwings]

Hello everyone, I'm new here, I am just stepping into the retro computer game and purchased a used computer for cheap, I've been basically cleaning the crap out of it and replacing parts with what I have and putting in a hard drive. Anyways I have an Asus A7V266-E and it has some capacitors that have some bulging at the top, no bursting yet, fortunately, however, I do want to replace the affected caps to prevent any hardware damage.

The caps specified are Nichicons 3300uF, 6.3v, 105*C, HM series, H0139. 10mm x 25mm

Someone recommended I start polymodding the board with these to start and wanted to double check that these were good polymer caps, I have a general understanding of the rule of thumb. I am open to other options.

https://www.digikey.com/product-deta...393-ND/2549489

[stj]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

i know you can get 2000uf, 6.3v because i'v used them.

[gryffinwings]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

i know you can get 2000uf, 6.3v because i'v used them.

Which ones were you using?

[stj]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

wurth, i think.
i'll look later.

[momaka]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

You can poly-mod it, but use 1800 uF caps minimum and fill in that empty spot.

However, seeing that this board has only 3 input caps and 4 output caps for the CPU VRM (+1 free/unpopulated spot for the output), you could use 5x Panasonic FR, 6.3V, 2700 uF, 10x25 mm for replacements. They are not quite on par with the Nichicon HM caps, but almost there. With the empty cap spot filled, you will have very close to the original total circuit ESR and capacitance.

Or you can mix the polymers with the electrolytics (i.e. maybe 2 poly cap and 3 electrolytic ones, or vice versa). I wouldn't go too low on capacitance, though. The controller feedback loop may not have been compensated for it and oscillate (very rare for this to happen on a motherboard, but still worth mentioning from a design standpoint).

[stj]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

large FC/K/M/R/S caps can cost more than polymers now.

[momaka]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

^True.
It's just the closest and easiest way to get a very close match on both capacitance and ESR of the original caps. I know capacitance doesn't have to match, and this board appears to have inductors on the CPU VRM with very few turns (hence, it's probably a pretty high frequency circuit as far as VRMs are concerned)... which means the circuit ESR matters a lot more than capacitance. (On some old boards, that's not always the case, and you may get coil whine and more noise than before).

Besides, the FRs above are also a good match for replacing failed 5VSB caps in many Delta, HiPro, and LiteOn PSUs, among others. So buying in bulks of 10 or more and keeping a few spare is not a bad idea.

[gryffinwings]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

^True.
It's just the closest and easiest way to get a very close match on both capacitance and ESR of the original caps. I know capacitance doesn't have to match, and this board appears to have inductors on the CPU VRM with very few turns (hence, it's probably a pretty high frequency circuit as far as VRMs are concerned)... which means the circuit ESR matters a lot more than capacitance. (On some old boards, that's not always the case, and you may get coil whine and more noise than before).

Besides, the FRs above are also a good match for replacing failed 5VSB caps in many Delta, HiPro, and LiteOn PSUs, among others. So buying in bulks of 10 or more and keeping a few spare is not a bad idea.

Here's the mobo that I am recapping, the caps circled in red are the ones I am replacing.



Also questions, can't you use a lower ESR and higher ripple current spec polymer cap and that would work?

[Uranium-235]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

those are either from the bad nichicon lot, or heat related, probably the former.

don't go too far lower on the ESR, ripple I think you can go as high as you want

does the northbridge fan still work?

i'm assuming you bought this one around to play with because my god thats an old chipset. Also limited to AthlonXP /w 266 FSB (Any athlon XP chip model number ending with C)

[momaka]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

Also questions, can't you use a lower ESR and higher ripple current spec polymer cap and that would work?

Yes, that will work.
Just don't go too low on the capacitance, though. I think 1500 uF polymers should be the minimum you go with here (and besides, there are only 5 cap spots).

Here's the mobo that I am recapping, the caps circled in red are the ones I am replacing.

https://scontent-lax3-1.xx.fbcdn.net...15&oe=5C3AC9D2

Yup, I figured those were the caps on your board too.
There are 4 caps, but you also have 1 unpoppulated cap spot you can fill (located next to the red circled caps on the right side of the above picture).

Last but not least...
this is an ASUS motherboard, which means the positive side of the caps should be aligned with the white-shaded semi-circle on the board (which is backwards to the standard that other motherboards use). Just keep this in mind so that you don't blow your new caps.

To remove all doubt, just mark the negative side of the original caps (the side with the white stripe on those Nichicon HM caps) on the board before removing them. Then place the new caps with their striped side to match what you marked on the board.

[gryffinwings]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

Yes, that will work.
Just don't go too low on the capacitance, though. I think 1500 uF polymers should be the minimum you go with here (and besides, there are only 5 cap spots).


Yup, I figured those were the caps on your board too.
There are 4 caps, but you also have 1 unpoppulated cap spot you can fill (located next to the red circled caps on the right side of the above picture).

Last but not least...
this is an ASUS motherboard, which means the positive side of the caps should be aligned with the white-shaded semi-circle on the board (which is backwards to the standard that other motherboards use). Just keep this in mind so that you don't blow your new caps.

To remove all doubt, just mark the negative side of the original caps (the side with the white stripe on those Nichicon HM caps) on the board before removing them. Then place the new caps with their striped side to match what you marked on the board.

Can I use an ESR rating of 8mOhms? What happens if you go too low? What benefit do I get from adding another capacitor to the board, I was under the impression that you shouldn't do that. Also, what is involved in adding another capacitor, sorry for all the questions, just trying to learn more about electronics, I have a basic understanding from my navy training.

[gryffinwings]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

those are either from the bad nichicon lot, or heat related, probably the former.

don't go too far lower on the ESR, ripple I think you can go as high as you want

does the northbridge fan still work?

i'm assuming you bought this one around to play with because my god thats an old chipset. Also limited to AthlonXP /w 266 FSB (Any athlon XP chip model number ending with C)

What happens if you go to low, would 8mOhms be ok?

The Northbridge fan does work, but I have a better heatsink/fan solution on the way to keep it cooler and reduce noise from the old cooler, it's a bit whinny. I figure lowering the northbridge temps will keep the board more stable.

Yes, I'm just playing with it, I know it's old, but it was cheap and it works with the really old games I intend to play, so no biggie. If anything I'll buy another computer if I want something more modern to play more modern games.

[momaka]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

Can I use an ESR rating of 8mOhms?

Considering the original HM caps have 12 mOhms ESR, 8 will probably work fine too. In general, I like to try keep the ESR within 20-30% of the original. Here, that's a little less than 35%. But should still be okay.

What happens if you go too low?

Possibly make the board unstable and crash (just like with the bad caps). In extremely rare cases (though I haven't seen this happen yet, but it's possible), this could damage components the board.

But again, how low is too low depends a lot on the circuit. On your board, I see that the CPU VRM coils have only 3 or 4 turns, which means the switching frequency is relatively high... which means the board will probably work with even lower ESR than normal... i.e. even 50% lower than original. But because I can't be 100% sure the repair will work fine, that's why I only suggest it as experimental.

What benefit do I get from adding another capacitor to the board, I was under the impression that you shouldn't do that.

Most of the time, those extra cap spots are there because the manufacturer made one "universal" design for many of their other motherboards. In this particular case, they probably didn't add a cap in that spot because it wasn't necessary (which means one part less to put on the board and one part less for the total cost of the board). Adding a cap in that missing spot is harmless at least and helpful at most. In this case, that empty spot just gives us more cap options to choose from (i.e. you can add more caps with lower capacitance than less with higher capacitance... which might be necessary, given how you won't find that high of a capacity for polymers).

Also, what is involved in adding another capacitor

Nothing special. Just clear the holes of the free cap spot, add the new capacitor in, and solder it.

sorry for all the questions, just trying to learn more about electronics, I have a basic understanding from my navy training.

No problems. Asking questions is always fine.

[mariushm]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

Be careful with the polarity of capacitors.
Typically on motherboads you have a drawing, a round circle with part of it filled - that part normally represents the negative side.

However, Asus (and Asrock,since they belonged to same group) like to do things the wrong way and for them, the filled portion represens the positive side. So if you're not careful you could install the capacitors the wrong way.

[gryffinwings]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

Considering the original HM caps have 12 mOhms ESR, 8 will probably work fine too. In general, I like to try keep the ESR within 20-30% of the original. Here, that's a little less than 35%. But should still be okay.


Possibly make the board unstable and crash (just like with the bad caps). In extremely rare cases (though I haven't seen this happen yet, but it's possible), this could damage components the board.

But again, how low is too low depends a lot on the circuit. On your board, I see that the CPU VRM coils have only 3 or 4 turns, which means the switching frequency is relatively high... which means the board will probably work with even lower ESR than normal... i.e. even 50% lower than original. But because I can't be 100% sure the repair will work fine, that's why I only suggest it as experimental.


Most of the time, those extra cap spots are there because the manufacturer made one "universal" design for many of their other motherboards. In this particular case, they probably didn't add a cap in that spot because it wasn't necessary (which means one part less to put on the board and one part less for the total cost of the board). Adding a cap in that missing spot is harmless at least and helpful at most. In this case, that empty spot just gives us more cap options to choose from (i.e. you can add more caps with lower capacitance than less with higher capacitance... which might be necessary, given how you won't find that high of a capacity for polymers).


Nothing special. Just clear the holes of the free cap spot, add the new capacitor in, and solder it.


No problems. Asking questions is always fine.

Thanks again, for all the excellent information, this has been very educational for me.

So at the moment, the capacitors I chose with the help from people from another forum will be very experimental. Here's a link:

https://www.digikey.com/product-deta...315-ND/5824538

Fortunately, caps aren't very expensive, so if they don't work, I can order different ones if necessary.

Be careful with the polarity of capacitors.
Typically on motherboads you have a drawing, a round circle with part of it filled - that part normally represents the negative side.

However, Asus (and Asrock,since they belonged to same group) like to do things the wrong way and for them, the filled portion represens the positive side. So if you're not careful you could install the capacitors the wrong way.

Thanks for the information, that is very odd to do that, I'll keep this in mind when soldering in the new caps on the motherboard.

[momaka]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

Thanks again, for all the excellent information, this has been very educational for me.

So at the moment, the capacitors I chose with the help from people from another forum will be very experimental. Here's a link:

https://www.digikey.com/product-deta...315-ND/5824538

Should work okay, I think, based on experiments I've done before with other boards.
Probably even just 4 of these caps will be fine. But if you get 5, you can replace one on the input/high side of the VRM too, since these are 16V caps.

@ $1.55, I wouldn't call them exactly cheap (capacitors for power supplies and monitors are usually even cheaper ), but they aren't expensive either. Let us know how it goes or if you need further help.

[gryffinwings]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

Should work okay, I think, based on experiments I've done before with other boards.
Probably even just 4 of these caps will be fine. But if you get 5, you can replace one on the input/high side of the VRM too, since these are 16V caps.

@ $1.55, I wouldn't call them exactly cheap (capacitors for power supplies and monitors are usually even cheaper ), but they aren't expensive either. Let us know how it goes or if you need further help.

So the ones I circled in red above are the ones I need to replace as the tops are bulging. I, in fact, did order 5 to have a spare just in case, which cap are you talking about on input/high side of the VRM?

So I inspect the problem caps every few days, and it looks like I will need to keep it powered down, noticed one of the caps is just starting to have a slight leak of a yellow substance at the top of the cap. So I will not be putting any power through this board until I have replaced the caps that are the problem.

[gryffinwings]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

Here are pictures of the leaking that has started, compared with the pictures posted at the top, it's already going downhill, wasn't expecting it to be this soon, oh well.

[momaka]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

which cap are you talking about on input/high side of the VRM?

The three caps right behind the purple parallel port. Replacing any of these with the polymer you got should be fine. In fact, looking more carefully at your picture, it looks like those are Nichicon HM caps as well (?) Please check. If they are, you might want to replace them too. All Nichicon HM, HN, and HZ caps made between 2001 and 2004 (along with most 6.3V batches from 2005) are known to have the same problem, especially the 6.3V-rated caps.

So I inspect the problem caps every few days, and it looks like I will need to keep it powered down, noticed one of the caps is just starting to have a slight leak of a yellow substance at the top of the cap. So I will not be putting any power through this board until I have replaced the caps that are the problem.

Once a cap bulges, that means it has already failed internally and pressure is building up inside. Leaking is just a sign that the internal pressure has gone far enough to rupture the vent/seal on the top.

Either way, when you see caps bulge, it's best to power down the device to prevent damage. Caps don't have to be leaking (or even bulging!) to be bad. Sometimes they can go bad while looking completely normal. But this pertains more to non-Japanese brands and caps that have been run in high-temperature environments for a long time.

Here are pictures of the leaking that has started, compared with the pictures posted at the top, it's already going downhill, wasn't expecting it to be this soon, oh well.

Oh yes, once those Nichicon HM, HN, and HZ caps fail internally, it doesn't take long for them to go completely bad.

No worries, though. Just replace them and everything will be okay, especially since the motherboard still appeared to work fine even with those quite failed caps. (Goes to show how much deviation in specs motherboards can take sometimes when it comes to capacitors. If you have an ESR meter, most of those caps will read high ESR with low capacitance or very low ESR due to high internal leakage tricking the meter).

[Wester547]

Re: Polymodding Asus A7V266-E, Capacitor Recommendations?

The three caps on the VRM input side are 1500uF 6.3V Nichicon HD (not to be confused with the failed 3300uF 6.3V Nichicon HM that are awaiting replacements, located on the VRM output side). They are used interchangeably with Rubycon ZL, Sanyo WX, and Chemi-con KZE in this position. Looking carefully at the second and fourth photo reveals part of the “HD(M)” series designation (“D(M)”, somewhat cut off in the photo but still quite visible) on the sleeve. Given that they’re seventeen years old now, it can’t hurt to replace them (or for that matter the OST capacitors scattered about the board). But I don’t think it’s mandatory.