Replace Multilayer Ceramic Capacitor on Asrock Z97E-ITX/ac

[MrCommunistGen]

Edit: I'm new to this forum -- I haven't even been lurking in the background -- so I'm not sure if this is the right place to be posting this query.  I poked around after posting and this seems to be more Software related troubleshooting.  Mods: I apologize if I got this in the wrong section.  Feel free to move this if it isn't in the right section.

 

I just received a used Asrock Z97E-ITX/ac board that I purchased on eBay.  According to the seller the board works.  I haven't yet put a CPU into it to test it myself, but that's next.  During unboxing I noticed that one of the Multilayer Ceramic Capacitors on the back of the board behind the VRM is missing.  I checked and it wasn't bouncing around inside the package -- that would be too easy.

I've done a bit of board recapping - but only for electrolytic capacitors where reading the values off of the label is really easy.  I have 0 experience with MLCCs.  Assuming the board works, I'd still like to replace the cap, but I don't know the voltage, capacitance, ESR, etc of the existing caps that are there.  Is my best bet to just pull one of the remaining caps off and check it?  I have a multimeter that has a capacitance mode, but this is only going to get me one of the measurements I need.

 

My google-foo isn't good enough to find a board circuit diagram for this (or really any other) motherboard.  Honestly, if I just knew what kind of MLCC to buy I could easily get this done...  This seems like something buildzoid would know offhand.

 

Should I just return the board as defective, or does the LTT collective think this is fixable?

Edited August 5, 2020 by MrCommunistGen
Added note to top stating I'm a noob to the LTT forum.

[startrek03]

There's nothing readable on these, right?

Maybe that can help you: https://www.quora.com/How-do-I-identify-an-SMD-ceramic-capacitor-and-how-do-I-find-its-value

It seems like the values are quite hard to find. You might end up having to measure it, unless you can find some sort diagram.

[startrek03]

Found this, maybe it can help: http://schematic-x.blogspot.com/2019/09/asrock-schematic.html?m=1

[MrCommunistGen]

2 hours ago, startrek03 said:

There's nothing readable on these, right?

Maybe that can help you: https://www.quora.com/How-do-I-identify-an-SMD-ceramic-capacitor-and-how-do-I-find-its-value

It seems like the values are quite hard to find. You might end up having to measure it, unless you can find some sort diagram.

 

Yeah... unfortunately they're definitely not labelled, unless they were attached label-side down.  That quora thread seems to imply that if you don't have the diagram that you're not going to be able to figure it out on your own.  It does at least somewhat narrow my search based on the color codes.  I can measure capacitance though idk if that works properly for MLCCs.  But there's too many other properties that are important that I don't think I can measure... at least not with the multimeter I have.

 

2 hours ago, startrek03 said:

Found this, maybe it can help: http://schematic-x.blogspot.com/2019/09/asrock-schematic.html?m=1

Wow. That's freaking amazing!  Thanks @startrek03!  The board I have isn't on there, but I'll pull up a handful of Asrock boards from that generation and see if I can identify the same SMD MLCCs in the layout.  If several boards use the same spec cap, then it is probably a reasonable bet that my board uses the same kind.  If there's variation, I can probably try to see if one of the other boards has a VRM configuration that matches what's on my board and use a board with a matching VRM for reference.

 

I don't have a copy of the Fritzing, so I'll need to shell out a bit of money, but that looks like something good to have anyway.

 

---

If anyone else has any potentially helpful input I'm still super open to anything else!

[Guest]

Is that just a fuse? Do you get voltage across the others but not that one? 

A quick repair would be a small jump wire if those are just fuses. 

[MrCommunistGen]

I dropped a spare CPU (an i3-4150T) into the board and it boots up.  I'm most of the way done installing a clean copy of Windows 10 and so far no errors.

 

2 hours ago, ShrimpBrime said:

Is that just a fuse? Do you get voltage across the others but not that one? 

A quick repair would be a small jump wire if those are just fuses. 

I don't think it is a fuse.  It was my impression that it is a capacitor.  I have yet to actually look through any of the board diagrams that @startrek03 linked above, so I'm not entirely sure.

 

I'm probably not going to have time to dive into the nitty gritty until later on in the weekend, but thank you to everyone who has chimed in so far!

[MrCommunistGen]

On 8/5/2020 at 7:15 PM, ShrimpBrime said:

Is that just a fuse? Do you get voltage across the others but not that one? 

A quick repair would be a small jump wire if those are just fuses. 

I'd forgotten that I was going on a trip this past weekend, and I've had a crazy week at work.  Finally got around to checking.  Do you mean for me to check the voltage with the board powered-off or powered-on?  Checking with the board powered-off, I'm not reading a voltage (0.0 mV) across the pads for the missing component or for any of those that are populated.

 

Edit:

Well now I feel a bit silly...

I powered up the system and checked the solder bumps for both the populated and unpopulated components.  They all read 12.20V - presumably the unfiltered DC voltage from the cheapo PSU I'm using for the tests.  Of course I'm not quite sure what that means.  Looking at my board pics again, you can see what to me appear to be different sets of traces that are joined by the missing component, which are presumably now decoupled from each other...

[Guest]

A fuse is inline. So your power red lead to one side of the fuse, and the other to ground will give you a reading.

 

If you where checking resistance or for an open (broken fuse) you'd have voltage on one side and not the other or can also check with continuity which is ground test lead one side of the fuse and red lead on the other. I like doing it by voltage because it should be the same for all the fuses.

 

But see, I'm not entirely sure that's a fuse. Can't tell by the picture. I think it was mentioned (different thread nvm) to remove one and flip it over. Fingers crossed it's stamped with something.

[MrCommunistGen]

I started poking around the board (literally) with my multimeter.  As oriented in the attached picture, the left-hand pad for each of the capacitors reads 0 ohms to ground.  The right hand side reads as a pretty big number that doesn't stay fixed at a single value.  I haven't desoldered one of the caps yet, but that's planned for this evening after it cools down a bit.  Even without pulling one of the caps off of the board, if I use the capacitance setting I get a reading of ~90μF +/- 1μF on each of the populated components.  This leads me to believe that they are in fact capacitors.  I'll see about getting a true reading after desoldering one of them.  And of course the holy grail would be to find some markings on the underside of the cap.

 

The nearest rating I can find on Mouser is for a 16V 100μF capacitor... and at least for low quantities they're NOT cheap for such a small part.  It looks like getting that combination of voltage and relatively high capacitance is costly.  Dropping the voltage down a notch to 10V or dropping capacitance down to 47μF each cut the cost roughly in half.

 

Thanks @ShrimpBrime for the continued input.  I'll update the thread when I have more to report.

[Guest]

Could be a cap. Looks like a Roland fuse maybe 2 amp or 2.5 amp, but generally colored white.

 

But yes I do look forward to your results.

[MrCommunistGen]

Short version:
I was able to desolder a cap and it measures ~10µF (10.2-10.3µF).

 

Long version:

I desoldered one of the caps, and then while trying to get the leads of my multimeter onto it with enough pressure to make good contact... it shot off onto the floor and disappeared forever. Since I'd probably killed the board anyway by removing a 2nd cap, I went for broke and pulled another one off and by being more careful was able to get a measurement.

 

Definitely no markings on the cap on any side.

 

So... now I need at least 2 replacements. Any suggestions or guidance would be appreciated. For starters since at this point 2 capacitors are missing and I've desoldered a 3rd. Would it make sense to just replace all 6 so that they match?

 

Shopping at either Mouser or Digikey, it looks like I'd need to source a 16V 10µF MLCC -- of which there are MANY. There's tons of resources available for electrolytic capacitors, but I've been having trouble finding info on MLCCs.

 

These are some of the properties I'm hoping to get some advice on:

1. Are there any particular brands I should consider or avoid? Right now the brands I'm considering are TDK, Samsung, Taiyo Yuden, and Kemet.
2. I'm currently considering X5R and X7R rated caps . I'm leaning towards X7R just to make sure what I'm getting is good enough. This is just a guess and not based on any sort of experience.
3. I'm looking at +/-10% tolerance parts. +/-5% are pretty expensive and I feel like that level of tolerance is overkill... but again, I'm not an expert.
4. I think that these are 1206 (in inches) capacitors, but I'm going to get some digital calipers to measure for sure. I seem to only have really crappy rulers that aren't anywhere near precise enough.

 

If MLCCs are outside of your area of expertise, no worries.  I found a recapping forum and posted some questions there where hopefully somebody with a specialty in electronics can be of assistance.

[MrCommunistGen]

Oh, also, @startrek03 FWIW I purchased a copy of Fritzing and then tried to view those Asrock board schematics you linked.  None of them seem to load. Idk if I'm doing something wrong or if maybe there's something I'm missing... I found a couple other sample diagrams around the internet and they load right up...

 

shrugs that's a different rabbit hole I don't feel like going down right now.

[startrek03]

10 hours ago, MrCommunistGen said:

Oh, also, @startrek03 FWIW I purchased a copy of Fritzing and then tried to view those Asrock board schematics you linked.  None of them seem to load. Idk if I'm doing something wrong or if maybe there's something I'm missing... I found a couple other sample diagrams around the internet and they load right up...

 

shrugs that's a different rabbit hole I don't feel like going down right now.

Tbh, I don't have any clue either since I just googled for board diagrams in general. I haven't even really soldered SMDs in general. Lol. I just wanted to help. 

But I definitely wish you luck on this journey. Maybe you'll learn how to repair boards and maybe this board even still works.

[MrCommunistGen]

As an FYI, I was able to solder on a bunch of replacement MLCC capacitors.  I did a pretty shoddy job because I'm not great at soldering.  I'll attach a pic if I can dig up one (though it's pretty embarrassing).  I never checked to see if the board would work with a bunch of those MLCCs missing for fear of damaging something, but I can confirm that with all my repairs the board seems to be working fine.

[startrek03]

2 hours ago, MrCommunistGen said:

As an FYI, I was able to solder on a bunch of replacement MLCC capacitors.  I did a pretty shoddy job because I'm not great at soldering.  I'll attach a pic if I can dig up one (though it's pretty embarrassing).  I never checked to see if the board would work with a bunch of those MLCCs missing for fear of damaging something, but I can confirm that with all my repairs the board seems to be working fine.

Congrats! It's great to see someone who doesn't do this sort of stuff on a regular basis repairing circuit boards.