sardinesandwich wrote on 2022-09-17, 13:59:

Filter capacitors:
200v 1000µF 85°c 50mm x 20.5mm diameter

https://www.digikey.jp/en/products/detail/nic … 2MELZ45/2540101

105°C capacitors: 50v 2.2µF 10.5mm x 4.5mm diameter 50v 4.7µF 10.5mm x 4.5mm diameter (probably, haven't removed this one yet) 5 […]
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105°C capacitors:
50v 2.2µF 10.5mm x 4.5mm diameter
50v 4.7µF 10.5mm x 4.5mm diameter (probably, haven't removed this one yet)
50v 22µF 10.5mm x 4.5mm diameter (this was hidden under some wires)
10v 4700µF 32mm x 12mm diameter
10v 2200µF 23mm x 9mm diameter
16v 3300µF 32mm x 12mm diameter
10v 1000µF 18mm x 7.5mm diameter
16v 470µF 13mm x 8mm diameter
16v 100µF 10.5mm x 6mm diameter

1) 50v 2.2µF 10.5mm x 4.5mm diameter
2) 50v 4.7µF 10.5mm x 4.5mm diameter
3) 50v 22µF 10.5mm x 4.5mm diameter
4) 10v 4700µF 32mm x 12mm diameter
5) 10v 2200µF 23mm x 9mm diameter
6) 16v 3300µF 32mm x 12mm diameter
7) 10v 1000µF 18mm x 7.5mm diameter
8) 16v 470µF 13mm x 8mm diameter
9)16v 100µF 10.5mm x 6mm diameter

Should I bump up the heat and give the areas around where the capacitors were in a bit of a clean and fresh solder? To be honest, I've never encountered something like this on a board before. (Just uploaded the picture, and I'm not sure why the quality is so poor. Can reupload if you'd like a better picture).

Yes, by all means... Get an inexpensive manual action desoldering pump for $5, that way, after you remove the solder from the leads, you just need to yank it out from the top. Just wiggle the leads to make sure they are truly free of the pad, otherwise you'll tear out the pad along with the trace when you pull the cap out from the top.

EDIT: Ah, wait a minute, I see what you mean... Apply flux to that area where the cap lead is located (on the underside)... While heating that part of the solder tilt the cap away with your other hand from the top of the board. Alternate from one lead side to the other lead side on the bottom with your iron until the cap comes out. Use the same method to install the new cap. No need to meddle too much with that area. The increased amount of solder is done by the manufacturer to increase current capacity for that trace. It's pretty common.

Make sure you don't reverse the polarity of any new cap you're inserting.

Which kind of glue are you referring to? Is it the organic type that turns dark brown?

mockingbird wrote on 2022-09-18, 01:21:

https://www.digikey.jp/en/products/detail/nic … 2MELZ45/2540101 […]
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sardinesandwich wrote on 2022-09-17, 13:59:

Filter capacitors:
200v 1000µF 85°c 50mm x 20.5mm diameter

https://www.digikey.jp/en/products/detail/nic … 2MELZ45/2540101

105°C capacitors: 50v 2.2µF 10.5mm x 4.5mm diameter 50v 4.7µF 10.5mm x 4.5mm diameter (probably, haven't removed this one yet) 5 […]
Show full quote

105°C capacitors:
50v 2.2µF 10.5mm x 4.5mm diameter
50v 4.7µF 10.5mm x 4.5mm diameter (probably, haven't removed this one yet)
50v 22µF 10.5mm x 4.5mm diameter (this was hidden under some wires)
10v 4700µF 32mm x 12mm diameter
10v 2200µF 23mm x 9mm diameter
16v 3300µF 32mm x 12mm diameter
10v 1000µF 18mm x 7.5mm diameter
16v 470µF 13mm x 8mm diameter
16v 100µF 10.5mm x 6mm diameter

1) 50v 2.2µF 10.5mm x 4.5mm diameter
2) 50v 4.7µF 10.5mm x 4.5mm diameter
3) 50v 22µF 10.5mm x 4.5mm diameter
4) 10v 4700µF 32mm x 12mm diameter
5) 10v 2200µF 23mm x 9mm diameter
6) 16v 3300µF 32mm x 12mm diameter
7) 10v 1000µF 18mm x 7.5mm diameter
😎 16v 470µF 13mm x 8mm diameter
9)16v 100µF 10.5mm x 6mm diameter

Should I bump up the heat and give the areas around where the capacitors were in a bit of a clean and fresh solder? To be honest, I've never encountered something like this on a board before. (Just uploaded the picture, and I'm not sure why the quality is so poor. Can reupload if you'd like a better picture).

Yes, by all means... Get an inexpensive manual action desoldering pump for $5, that way, after you remove the solder from the leads, you just need to yank it out from the top. Just wiggle the leads to make sure they are truly free of the pad, otherwise you'll tear out the pad along with the trace when you pull the cap out from the top.

EDIT: Ah, wait a minute, I see what you mean... Apply flux to that area where the cap lead is located (on the underside)... While heating that part of the solder tilt the cap away with your other hand from the top of the board. Alternate from one lead side to the other lead side on the bottom with your iron until the cap comes out. Use the same method to install the new cap. No need to meddle too much with that area. The increased amount of solder is done by the manufacturer to increase current capacity for that trace. It's pretty common.

Make sure you don't reverse the polarity of any new cap you're inserting.

Which kind of glue are you referring to? Is it the organic type that turns dark brown?

Wow, thank you so much!

I picked up a nice desoldering pump actually (engineer ss-02) and for the most part removing the capacitors was a breeze. I only had trouble with one capacitor. I had to increase the heat of the iron, but I just heated the area and applied a gentle pull on the cap and it came right out. I made sure not to be harsh with the board. Hopefully installing the new capacitors isn't too tricky in that area. I have marked out the polarity on the capacitor map and it's also well marked on the board. I also numbered each spot on the board to match with the capacitor map and I numbered each capacitor removed.

Regarding the glue - It's a caramel colour. The issue is that it's covering pretty much the entire capacitor leg, plus some surrounding resistors. I've attached a picture of the area.

Edit: I noticed that two of the capacitors you listed are 6.3v instead of 10v.
4) 10v 4700µF 32mm x 12mm diameter
5) 10v 2200µF 23mm x 9mm diameter
I always understood that you should replace capacitors with an equivalent or greater voltage. I trust your choices, but I am curious as to why lower voltage capacitors are applicable in this case. Also, thanks again for helping me.

sardinesandwich wrote on 2022-09-18, 02:05:

I picked up a nice desoldering pump actually (engineer ss-02) and for the most part removing the capacitors was a breeze. I only had trouble with one capacitor. I had to increase the heat of the iron, but I just heated the area and applied a gentle pull on the cap and it came right out. I made sure not to be harsh with the board. Hopefully installing the new capacitors isn't too tricky in that area. I have marked out the polarity on the capacitor map and it's also well marked on the board. I also numbered each spot on the board to match with the capacitor map and I numbered each capacitor removed.

Ok, all the better, good on you.

Regarding the glue - It's a caramel colour. The issue is that it's covering pretty much the entire capacitor leg, plus some surrounding resistors. I've attached a picture of the area.

It's not hard as in solid, is it? Looks like caramel-coloured ordinary silicone to me... Just cut it away with a blade or something... If it's hard, use a heatgun to soften it a bit then peel it all off in one piece.

Edit: I noticed that two of the capacitors you listed are 6.3v instead of 10v. 4) 10v 4700µF 32mm x 12mm diameter 5) 10v 2200µF […]
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Edit: I noticed that two of the capacitors you listed are 6.3v instead of 10v.
4) 10v 4700µF 32mm x 12mm diameter
5) 10v 2200µF 23mm x 9mm diameter
I always understood that you should replace capacitors with an equivalent or greater voltage. I trust your choices, but I am curious as to why lower voltage capacitors are applicable in this case. Also, thanks again for helping me.

Yessir... 10V capacitors on PSU secondaries are for the 5V rail... I picked 6.3V for you because the 10V variants were more expensive on Digikey...

Good luck and report back.

mockingbird wrote on 2022-09-18, 03:14:

Good luck and report back.

Hello! The capacitors arrived and I installed them all. Turns out one of the capacitors had a leg soldered to the leg of a Zener diode under all that silicone. Looking at the image now, I can a big blob of solder peaking out.

Anyway, it all works perfectly! The system is very stable now. I checked the voltages with a multimeter and everything looks good. Thank you so much for all your help.

On another note, do you have any suggestions for resources to learn more about capacitors? I recently picked up another Socket A board (Asus A7v880) with a newer chipset (VIA KT880) that has some bad chemicon KZG capacitors. It costed next to nothing and came with a CPU in it too. I wouldn't mind replacing the capacitors on it some time later this year, but I figure that I should probably learn more about what's going on electronically first before just replacing them.

Once again, thank you for all your help.

sardinesandwich wrote on 2022-09-25, 14:37:

Anyway, it all works perfectly!
...
I recently picked up another Socket A board (Asus A7v880) with a newer chipset (VIA KT880) that has some bad chemicon KZG capacitors. It costed next to nothing and came with a CPU in it too.

Good for you!

For the A7V880, you have VRM high and VRM low capacitors in the VRM. There are no electrolytic equivalents of KZG still being manufactured anymore (perhaps SunCon still produces WG series - but I don't recommend it).

The standard operating procedure is to go with polymer capacitors. So you'll probably need something like 16V 270uF in 8mm for VRM high (to replace 16V 1000uF KZG 8mm), and 6.3V 820uF for VRM low (to replace 6.3V 1500uF KZG 8mm).

You can go higher in capacitance for VRM high or low, but keep in mind that good polymers get more expensive the higher the capacitance. You're looking at a dollar a piece or more as it is. Nichicon/UCC/Panasonic are good. Stay away from the other brands.

The reason you can get away with much lower capacitors in these newer-type VRMs is because ripple suppression is more important in their designs than is bulk capacitance. And polymer capacitors have a much higher ripple suppression capability than electrolytics.

They are not suitable for most power supply circuits (like pi filters) however because of their extremely low ESR (though you do very often see them in newer PSUs with DC to DC circuits that are designed specifically for them).

The only other thing I can say is that replacing caps on a motherboard won't be as easy. You're going to have to heat through ground planes and multiple PCB layers. It's really best to practice on a scrap board first if you've not done it before.

Thanks! I have been doing a lot of reading about using polymer capacitors on motherboards.
Non VRM capacitors are nearly all 6.3v 820uF KZGs, minus a handful of tiny 16v and 25v capacitors.
The VRM capacitors are a mix of 6.3v 1500uF KZGs and 6.3v 1500uF Panasonic (not sure of the series, black and gold sleeving). These KZGs are taller than the equivalent capacitors in the KZG data sheet. Around 20mm versus the data sheet's 12.5mm.

Only some of the 6.3v 820uF capacitors are visibly bad, but I think it would be best to replace at least all of the KZGs.
I figure I can use the same 6.3v 820uF polymer capacitors across the whole board (half capacitance for VRM, same everywhere else).

Like you said, good polymers get expensive. Shipping to here gets rather pricey, so I've looked at several different sources.
These Nippon Chemi-Con capacitors are the most affordable, and the minimum order amount is perfect for what I will need. Accounting for differences in shipping costs, it works out to be around half the price of digikey/mouser.
However, will they be appropriate for this application?
https://jp.rs-online.com/web/p/polymer-capacitors/1749931

sardinesandwich wrote on 2022-09-30, 17:38:

Only some of the 6.3v 820uF capacitors are visibly bad, but I think it would be best to replace at least all of the KZGs.

KZG do not always bulge when they go out of spec. Definitely concentrate on the VRM. The Panasonic gold/black capacitors are something like FL or FJ series. I would replace those as well, since they're quite old. Since this VRM has no 16V caps, it seems like it's deriving its voltage from the 5V rail... so any 6.3V polymer with reasonable capacitance should do fine here.

I figure I can use the same 6.3v 820uF polymer capacitors across the whole board (half capacitance for VRM, same everywhere else).

I wouldn't waste any money on polymers for the rest of the board... Any decent series will do fine here... Just make sure they're 8x11.5... Any taller, you might risk them physically interfering with PCI cards.

mockingbird wrote on 2022-10-02, 02:50:

I wouldn't waste any money on polymers for the rest of the board... Any decent series will do fine here... Just make sure they're 8x11.5... Any taller, you might risk them physically interfering with PCI cards.

Understood.

How important is ESR and ripple for the non VRM capacitors? All the non VRM 6.3v capacitors are KZGs, and as you said before, there aren't any electrolytic equivalents still being made. Hence why I figured I would use polymers across the whole board. If it's not that important then I'll go for something like Rubycon ZLH capacitors.

Edit: Just compared different combinations, and it looks like all polymers will still work out cheaper than ordering a mix. There's a total of 24 capacitors to replace. 8x 1500uF (VRM) and 16x 820uF (non VRM). The unit pricing on those PSFs I sent before works out to be the cheapest by far. RS also has considerably cheaper shipping (650 yen vs 2000 yen for digikey/mouser). If the considerably lower ESR in non VRM capacitors won't cause issues then I think I'll use polymers across the whole motherboard.