Asus TUF Z390Plus Gaming. Missing capacitors

[dicky96]

This board has 14 missing electrolytic capacitors. I have no idea why, that is how I got the board. Whoever removed them did a pretty decent job of it and used flux which was still on the board making it easy to see where they had been working. The only thing I have done so far is used my vacuum desoldering tool to clean the holes of old solder.

As I say, I have no idea why this obviously reasonably skilled person has removed the capacitors as I don't read a short across any of them.

The three near the DIMM and ATX connector slots all read 546ohms (these are all in parallel)

The two near the buck regulator by the SATA ports read 21.8 ohms and are parallel and go to this coil

I'm not quite sure where the other one near the SATA connectors goes to - it doesn't go to the buck coil very close to the dimm sockets like I would have expected. This one reads OC.

Actually while typing I spotted another one missing, near to USB1112 connector.

Other than that there are some 'scuffed' pins in the LGA connector but under the microscope they look pretty much OK.

So I guess the only thing to do first is replace the capacitors. Of the ones still on the board there are some 270uF 16V and some 560uF 6.3V.

None of the missing ones connect to 12V on the ATX connector or EATX12V, so it is a good plan to replace all the missing caps with 560uF 6.3V? And what type are these black capacitors?

Cheers

[momaka]

Re: Asus TUF Z390Plus Gaming. Missing capacitors

So I guess the only thing to do first is replace the capacitors. Of the ones still on the board there are some 270uF 16V and some 560uF 6.3V.

None of the missing ones connect to 12V on the ATX connector or EATX12V, so it is a good plan to replace all the missing caps with 560uF 6.3V? And what type are these black capacitors?

Anything that is next to a coil/inductor (i.e. part of a buck regulator circuit), you'll probably want to replace with very low ESR electrolytic or preferably even polymer. 6.3V is a pretty safe bet, should any voltage be 3.3V or 5V. Most likely, anything in the range of 470 uF to 1000 uF will work, so just use what you have - that is, if you have any junk GPUs and motherboards with spare polymer caps.

Now, for the missing caps next to those inductors next to the CPU socket, you could probably use 2.5V or 4V caps with higher capacitance, and you'll want good polymers here too.

Lastly, for caps connected to the 5V/5VSB line for the USB ports, you can probably use any cap rated for at least 6.3V and 470 to 1200 uF. It doesn't even have to be polymer. Regular electrolytic should do too. Just make sure the cap really is connected to 5V or 5VSB and not 12V (as it may be the case with Firewire or certain USB 3.0 supplies.)

Oh, and if the guy removed those caps so skillfully, maybe there is indeed an issue with the board and that's why he didn't bother saving it. So just keep in mind that this motherboard may have more issues than just missing caps. Hopefully not, though - that would be nice, for sure.

[dicky96]

Re: Asus TUF Z390Plus Gaming. Missing capacitors

Yeah there must be a reason those capacitors were removed, but none of them read short - and personally I can't think of any other good reason to go round removing them.

So maybe this is someone who can desolder well but doesn't have fault diagnosis skills? Which kinda says, yes there probably is something else wrong with it! But I can't really get to that until I replace the caps.

I think I will just order some 560uF 6.3V as I suspect that Asus probably just used the same capacitors everywhere, apart form the 16V ones on the 12V rail. It looks like some of the capacitors on Vcore are still there - and they are 560uF 6.3V

Are this type OK, Nippon PSE? I can't find any black ones.
https://www.aliexpress.com/item/4000...archweb201603_

I can check the dimensions against one of the ones still on the motherboard as they have to fit under the fancy heat sinks

rich

[momaka]

Re: Asus TUF Z390Plus Gaming. Missing capacitors

Yeah there must be a reason those capacitors were removed, but none of them read short - and personally I can't think of any other good reason to go round removing them.

So maybe this is someone who can desolder well but doesn't have fault diagnosis skills? Which kinda says, yes there probably is something else wrong with it! But I can't really get to that until I replace the caps.

Yup, that's what I'm thinking.
Either that, or "they" (whoever that may be) have the skills and determined the board not worth repairing, so they stripped the caps out of it to repair something else... maybe?

I think I will just order some 560uF 6.3V as I suspect that Asus probably just used the same capacitors everywhere, apart form the 16V ones on the 12V rail. It looks like some of the capacitors on Vcore are still there - and they are 560uF 6.3V

Yeah, that should work fine.

Are this type OK, Nippon PSE?

Yeah, PSE and PSC series are often used on video cards VRMs too. They will do fine. PSC, in general, has slightly better RC specs and more capacitance and voltage options... but for 6.3V, 560 uF, they have nearly identical specs.

Just be careful that those AliExp. caps are genuine (probably are though - I've heard many are re-sold from left-over manufacturing of other products.) But we will see, I suppose.

I can't find any black ones.

Black spray paint?

I can check the dimensions against one of the ones still on the motherboard as they have to fit under the fancy heat sinks

UCC PSE 6.3V 560 uF polymers are 6.3 mm diameter x 8 mm height, according to the datasheet.
Meanwhile, PSC is 8x8 mm. So check what will fit. I don't think you can find many choices below 8 mm, though.

[dicky96]

Re: Asus TUF Z390Plus Gaming. Missing capacitors

Yup, that's what I'm thinking.
Either that, or "they" (whoever that may be) have the skills and determined the board not worth repairing, so they stripped the caps out of it to repair something else... maybe?

Yeah possibly that, but if you were gonna do that wouldn't you take all the ones from around Vcore? At least I would take all of them, for the extra time it would take

I ordered a bag of 100x 560uF 6.3V PSE inc postage for about €9. One of the reviewers who left feedback gave 5 stars said this was his actually second order from this seller for the same capacitors - so probably yeah, they will be OK

Just gotta wait a few weeks for them now.

[momaka]

Re: Asus TUF Z390Plus Gaming. Missing capacitors

Yeah possibly that, but if you were gonna do that wouldn't you take all the ones from around Vcore? At least I would take all of them, for the extra time it would take

That's true.
Maybe the person had the CPU in there and did a resistance test, thinking the low resistance is a short-circuit and started removing caps?? Ah well, know knows anymore.

I ordered a bag of 100x 560uF 6.3V PSE inc postage for about €9. One of the reviewers who left feedback gave 5 stars said this was his actually second order from this seller for the same capacitors - so probably yeah, they will be OK

Sounds good then. Let us know, if you get a chance, how they turn out.
The price for those is not bad at all.
I already have enough polymers in stock, thanks to dead video cards that can't be fixed. And for older large-capacity ultra-low ESR motherboard caps, I still have a few dead Xbox 360 boards to salvage parts from. If you I could find a cheap source of used/recycled genuine high-voltage electrolytic caps for input filtering, that would be grand. The bigger ones for APFC PSUs get expensive quickly.

Just gotta wait a few weeks for them now.

Yeah, for some reason it takes longer for stuff from East Asia to come to EU than it does to US. I suspect they come here through the West coast shipping ports, after which it's just a few days for the ground shipping to get it around the country. I've been getting stuff from China in as little as 12-14 days total.