Fixing bulging mobo caps?

[Zando_]

As the title says, I'm wondering how to fix bulging capacitors on a mobo. I got an old home server from a friend, and their tech guy said it was slowly dying, and I'm thinking that's why. It's an old ASUS Crosshair mobo, with a quad core AMD Phenom CPU, an unknown amount of Kingston HyperX DDR2 RAM, and a GT 7300 (I think). I don't have any pics right now, but three of the caps in the area below the main PCIe slot and to the left of the chipset heatsink are bulging. I assume that's bad, but will it work with them, or do I need to replace/repair them?

[Anghammarad]

I have a board that has the same issues. Onboard lan died, system got unstable. I'm about to switch out those caps to new ones and see if it then works. With luck and a little skill it should work out. But then who knows what else is dying of age on the motherboard.

 

[Bananasplit_00]

you would have to replace them, its not all that dificult as long as you have a decent soldering iron. buy new ones with the same values and just reaplace them

[Zando_]

Just now, Bananasplit_00 said:

you would have to replace them, its not all that dificult as long as you have a decent soldering iron. buy new ones with the same values and just reaplace them

Awesome! What's the best place to get them?

[Bananasplit_00]

1 minute ago, Zando Bob said:

Awesome! What's the best place to get them?

duknow seeing as i dont tend to buy caps but anywhere that sells that kind of stuff. in Sweden there are a few stores that sell them for example but online should be quite a bit cheaper

[mariushm]

If you're in US, look at Digikey.com , Mouser.com or Newark.com

 

If you take some pictures of your motherboard and point the ones you need to replace (well you wouldn't need to point them, i'd see which are visibly bad... basically i want to see what's written on them to suggest good replacements), i may be able to suggest something that would work for you and would be cheap.

If you can't take pictures at least write down what's written on them

 

[TheComputerdude]

14 minutes ago, Zando Bob said:

Awesome! What's the best place to get them?

amazon what can you not get on amazon 

[Senzelian]

8 minutes ago, TheComputerdude said:

amazon what can you not get on amazon 

a Linus without socks and sandals?

[TheComputerdude]

1 minute ago, Senzelian said:

a Linus without socks and sandals?

true

[H0R53]

37 minutes ago, TheComputerdude said:

amazon what can you not get on amazon 

1. A replacement for my laptop's hard drive ribbon and the plastic door that holds it in place

2. Hookers

3. Cocaine

[TheComputerdude]

Just now, H0R53 said:

1. A replacement for my laptop's hard drive ribbon and the plastic door that holds it in place

2. Hookers

3. Cocaine

you can if you know where to look

[H0R53]

5 minutes ago, TheComputerdude said:

you can if you know where to look

I've looked.

 

Joking.

[TheComputerdude]

1 minute ago, H0R53 said:

I've looked.

 

 

  Reveal hidden contents

Joking.

 

and I wish I hadn't

 

[porina]

I've done it in the distant past. You need quite a powerful soldering iron to heat up the ground plane caps are often connected to. I'm not sure it is worth the pain on an older board.

 

On sourcing caps, try to match as best you can on capacity, voltage, temperature, ESR, and physical size. This might not be as easy as it sounds. If you can't get exact replacements, you could go for "close enough" and drop on some of those at the cost of reduced lifespan.

[asand1]

Going higher voltage will increase the life expecancy of the caps. 

[Zando_]

7 minutes ago, asand1 said:

Going higher voltage will increase the life expecancy of the caps. 

Wow. I would never have thought of that! 

[mariushm]

The life span of a capacitor depends on the electrolyte formula used inside the capacitor and the volume of the capacitor. 

Sometimes, a capacitor rated for higher voltage will have a bigger volume (will be slightly taller or slightly bigger in diameter) so naturally, the lifetime rating may be higher.

 

However, the lifetime rating is not generally something you have to worry about. Any quality series of capacitors these days will basically last you at least 10 years, even if it's rated for let's say only 2000 hours at 105c.

 

For electrolytic capacitors, you generally double the life for every 10c decrease in operating temperature. So if you have a 4000h @ 105c electrolytic capacitor and during operation is staying at 65c (it gets warm through the circuit board due to proximity to hot components), that means the capacitor would still be within specifications after  64000 hours .. that's 2666 days or ~ 7 years of continuous use at that temperature (8000h @ 95c , 16k hours at 85c , 32k hours at 75c , 64k at 65c and so on)

 

For solid (polymer) capacitors the lifetime rating is estimated differently, there's no basic approximation. To keep things simple, even a 2000h @ 105c polymer capacitor will last at least 10-15 years if the temperature is at the levels normally found on motherboards (40c .. 70c)

 

Capacitors on motherboards must have low esr in the first place, then you generally want to buy capacitors with the same pitch (distance between leads) to make it easy to insert them and have them as close to the motherboard as possible (that matters a lot). Then you also have to be careful about diameter and height - too tall and some heatsinks may no longer work with that motherboard.

You can play with the voltage rating (for example you can replace 4v rated polymer capacitors with 6.3v polymer capacitors , or you can replace 10v rated electrolytic capacitors with 16v rated electrolytic capacitors without any problems.

If you know what you're doing, you could also use capacitors with different capacitance value in some places... but only if you know what you're doing. Generally, you should keep the capacitance value the same or slightly higher than the old capacitors' value.

 

 

[Zando_]

On 6/8/2017 at 10:24 AM, mariushm said:

If you're in US, look at Digikey.com , Mouser.com or Newark.com

 

If you take some pictures of your motherboard and point the ones you need to replace (well you wouldn't need to point them, i'd see which are visibly bad... basically i want to see what's written on them to suggest good replacements), i may be able to suggest something that would work for you and would be cheap.

If you can't take pictures at least write down what's written on them

 

Sorry I took so long...  Here's the pics:

 

[mariushm]

Ok, pictures are good but sadly I can't read the capacitance and voltage rating because they're printed on the other side (closer to the negative strip). What I see in the pictures is just some internal manufacturing code, like production week and year.

 

Still I made circles around the capacitors that you MUST replace in order to get your board working (in RED) and a few that you SHOULD replace (in YELLOW) but most likely the motherboard will work without them being replaced.

 

The ones in ORANGE ... they look like low capacitance capacitors for smoothing out fan voltage  or for usb connectors or for less important things, and if that's the case they shouldn't have to be replaced but it's really hard to tell from pictures if they're ok or not. Also since they're in the path of airflow from the vrm heatsinks , they could be constantly warm during operation so I suppose it wouldn't hurt to be replaced as well. So I'd say they're somewhere between red and yellow, hence the orange color

 

Those capacitors should have a capacitance value printed on them (like 820uF for example) and a voltage rating (should be mostly 6.3v or 16v, because the motherboard works with 5v and 12v)

Below you'll find two links to Digikey (a reputable store of electronic components), one for polymer capacitors and one for electrolytic capacitors. I pre-filtered the list to show only series and brands of capacitors that are suitable for your motherboard, but you still have to pick the capacitance + voltage rating combination.

 

If a capacitor on the motherboard is rated for 6.3v, you can safely buy a capacitor rated for 10v or even 16v and use that on the motherboard instead. You may want to do that for example, to get a cheaper price is you buy a pack of 5 or 10 capacitors, instead of buying several different capacitors.

If you decide to use polymer capacitors (solid), it should be fairly safe to use capacitors one step below the capacitance you have on the motherboard. For example, if the capacitor is there as 820uF 6.3v, then it should be fairly safe to use 680uF 6.3v (or rated for 10v or 16v) but you should try to keep the capacitance value the same. I'm telling you this because you may find one capacitance +voltage rating combination too expensive (or you may have to buy a minimum of 10), in which case you may find the "one step smaller" version much cheaper.

 

Last, one very important thing: This is an Asus motherboard and Asus along with Asrock (both part of Pegatron group) like to put the capacitors the other way around on the motherboards.  Normally, the motherboard has a circle with half of it filled in... and the normal way is that the filled half circle represents the negative side (where you'd insert the lead of the capacitor that's near the negative strip of the capacitor).  However, Asus does it the other way around, negative is the empty half-circle.  Just remember not to put the capacitors the wrong way in.

 

Here's solid (polymer capacitors) :  https://www.digikey.com/short/3dv8d2

Here's electrolytic capacitors : https://www.digikey.com/short/3dvj7f

 

The electrolytic capacitors are sorted in a sort of "best performance" first, you don't have to get the highest performance ones from the list, but a cheaper one from the middle of the page or the next page (and which matches capacitance + voltage rating).

The polymer capacitors are just sorted by price, as there's smaller selection and all i selected there exceed the specifications required by the motherboard.

 

Also note that I've set it to show prices for buying minimum 5 pcs of each, i did that because for a lot of results, the store has two listings, one for buying a few pieces and one for buying minimum quantities like 1000 or 2500pcs (and these listings would have showed up at the top and would have confused you).

So the price for buying just one or two may be slightly higher than the one shown (which is for buying 5pcs at least)

 

 

 

 

[Zando_]

@mariushm (sorry it's been so long again). I've got a pic of the caps, and look like they're 6.3v 820uf. Should I get polymer or electrolytic caps? 

[mariushm]

Replace with 680uF or 820uF 6.3v polymer or 820uF 10v or 16v electrolytic (can be 6.3v if you really want to, but 10v rated capacitors should be the same diameter so no point going with 6.3v if you don't have to)

[Zando_]

10 minutes ago, mariushm said:

Replace with 680uF or 820uF 6.3v polymer or 820uF 10v or 16v electrolytic (can be 6.3v if you really want to, but 10v rated capacitors should be the same diameter so no point going with 6.3v if you don't have to)

Awesome, thanks! Are the polymer ones better or something, or what's the difference?

[Zando_]

@mariushm, how about this: https://www.digikey.com/product-detail/en/rubycon/10ZLJ820MT810X12.5/1189-1530-1-ND/3134486