Dell GX-260 motherboard repair... cap appropriateness question.

[Stevevil]

Hi again gang! Last time I posted here I was working on my IZ3D monitor (I'm using it now to write this, 3 months later!) Thanks for those who helped me choose correct components.

This time I'm about to recap ELEVEN bad nichicon caps on my old firewall box. I had to retire this SFF firewall box over 2 years ago because it wouldn't start 19/20 times I tried. Opened her up and whoa, lots of swollen caps.
I found a recap kit on the CapKing website last year, but I'm just now getting around to pulling the mobo and looking at what I ordered. I've had good luck with their kits in the past but I know alot more about capacitors now after the clinic you guys put on for me with my monitor repair, so I'm being a little more choosey with what I use.
I'm pretty confident in the caps they sent me but the picture on their site is obviously for a rev 2 board where mine is a rev 3 (slightly different capacitor layout, and probably different values on a few).
Fortunately, ALL the capacitors that I can visually identify as bad are identical and the replacements sent include 2 extras of that model.
I would love one of you Capacitor experts (cause I'm not even close) to look at the specs (which at least I learned enough to be able to provide these correctly) and tell me if these will give me any problems?

Original:
nichicon 2200uf 6.3v HM-series
code: 239
size: 10x20
impedance: 13 (mOhm)
rated ripple: 2550 (mArms)
-------------
Replacement (capking):
Rubycon 1500uF 10v MCZ-series
code: ???
size: 8x20
impedance: ???
ESR: 12 (mOhm)
Rated Ripple: 2350

The specs look very close to me except that 2200 being taken down to 1500, that seems not right to me. Is that going to be ok? I mean the site says they've used these to replace them many times but the picture shows these should be 1500uF v6.3 (which is of course lower, but the fact the picture doesn't match up and the specs of the capacitors they sent are different from the ones on the picture really makes me nervous). I'm not sure what replacing 2200s with 1500s will do but I'm pretty sure that was one of the most important numbers to match up on my last recap adventure.
Experts, what do you think? Trust em and soldier them in or start looking for replacements myself? (I spent 19$ on this kit last year so I'm hoping they will work.)

[theOracle]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

NO, do not change the original capacitance specified in the circuit!

the Rubycon MCZ is no longer made because it had some issues!

try this one:

Rubycon 2200uF 10v ZLG-series
size: 12.5x20
impedance: 13 (mOhm)
Rated Ripple: 2480


PS - never trust a place that would have you use a totally incorrect capacitor, just because they apparently cannot obtain the correct one!

also, you can go to Digi-Key and find other suitable replacements for your application in Nichicon, Panasonic and Nippon Chemi-con (United Chemi-con)

[u271D]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

Electrolytic caps are typically rated +/- 20% so you can normally put a cap that's within that range. For you that would be 1760uf to 2640uf.
Higher voltage and Lower ESR is normally better.
But lower ripple not so good. That number is not about how big of a ripple its letting through; but how big of a ripple it can withstand. So higher is normally better.

NOTE: the specs I found for a nichicon 2200uf 6.3v HM-series says the impedance is 10 not 13, so you might want to check you data again

So my thought is, no, it's not a good replacement.

[PeteS in CA]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

Steve, be sure to check what Topcat can offer. He knows these caps almost well enough to make Mrs. TC jealous. And he lives in the state next door to you, IIRC.

[Stevevil]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

Ok, so these are trash then? I was afraid of that. I wish I had come here before I ordered those last year (I had no clue at the time).

I have 10 of these on hand but the specs look outta whack to me on these too...
Nichicon 2200uf 6.3v HZ-series
Code: H1127
Size: 10x20
impedance: 7 (mOhms)
Rated Ripple: 3770 (mArms)
Plus I need 11 and I only have 10 of these.

Oracle, the only problem with those is these are in a tight line around a CPU so I don't think I could fit 12.5 dia caps in there. Anyone got suggestions for 10mm dia replacements?
I found this one at digikey: UHM0J222MPD-ND
It appears to be identical on the specs of my original part. Will this one work? Pete, I really trust your opinion and would love to hear what you think too.

Hey, btw, I noticed the specs sheet says lifetime: 2000hrs/105c
That's only 83 days! I plan on this PC being on 24/7 since it's my primary firewall. I realize that's the failure specs for 105c which is pretty dang hot, but these things last a LOT longer than that in normal heat ranges right? I mean, the original worked for 6 years before failing (and that was defective cap-plague parts).

Also, since this appears to be the EXACT original part, have they fixed the problem with these so they won't fail again or are these left over stock from the bad batches back in the early 00s?

[theOracle]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

go to Digi-Key and put in just the very minimum parameters you must have and their filters will spit out all of the great caps that fit your need - I generally would do it like this, on your applicaton, I would specify acceptable makers as Nichicon, United Chemi-con, Panasonic and Rubycon, I would then specify the following:

"through hole", bulk packaging, the physical size you require, a voltage range of the original and the next several higher, 2200uF, acceptable temperature ratings, "in stock" status, and then get the results and sort those by impedance or ripple current, and several good choices you didn't know existed will jump out at ya - it's fun!

remember, using the control key, you can select multiple voltages, temperatures, makers, etc.

[Stevevil]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

Ok, well I'm just going to order the same brand, model as the original since they are still available. I just hope they made new runs of these caps without the bad formula or I'll be throwing out this motherboard in a couple of years.
I really didn't expect to be able to find the original parts so thanks for everyone's input and help!

[theOracle]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

yes - Nichicon just had a bad period with these caps, they are fine now - Just like Chemi-con has had one bad series, out of billions of caps produced each year

Just stick with the 4 marquee brands!

[Topcat]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

here's the original:
https://www.badcaps.net/store/produc...roducts_id=181

[kc8adu]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

actually the 1500's would work fine.
the esr and ripple are close.considering i replace them with 820@2.5 polys and they do just fine.
but i agree that one should replace with like specs if you do not understand the circut well enough to substitute.

[theOracle]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

actually the 1500's would work fine.
the esr and ripple are close.considering i replace them with 820@2.5 polys and they do just fine.
but i agree that one should replace with like specs if you do not understand the circut well enough to substitute.

At MIT, I learned that if the original engineer had wanted a 1500uF or an 820uF capacitor, that is what he would have specified in the design.

there is no worldwide shortage of great quality 2200uF caps, so the OP needs to use what was specified in the original design, rather than some cap that is out of spec for the circuit.

and Topcat's idea of using the exact capacitor it came with new is a great idea indeed!

[momaka]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

The specs look very close to me except that 2200 being taken down to 1500, that seems not right to me. Is that going to be ok?

In a pinch, it will work, and possibly long term too without any consequences either (although I shall note that Rubycon MCZ is not very tolerant of heat, so if that GX-260 uses a SFF case, then this is probably not the best idea).
However, the biggest problem is those Rubycon MCZ's your posted the info for are 8 mm diameter whereas the old caps are 10 mm diameter. That means you'll probably have to have the caps sitting a few mm in the air above the motherboard - which generally isn't desirable.

Ok, so these are trash then?

Trash - not really. You never know when you might need them for another motherboard or project.

Hey, btw, I noticed the specs sheet says lifetime: 2000hrs/105c
That's only 83 days!

The capacitor "lifetime" you see in data sheets is NOT the lifetime of the cap while it is in use. It is the lifetime of the cap while in use, under full voltage ratings, full ripple current rating, and operated at its maximum temperature of 105C.
In other words, the "lifetime" or sometime also called endurance is the minimum guaranteed time the capacitor will work under full rated conditions. Furthermore, as a rule of thumb, for every 10C drop in the capacitor's temperature under its maximum rated temperature, the lifetime/endurance of the cap doubles.
So let's say your cap is fully loaded and running at 105C. That means, that capacitor will last at least 2000 hours and still be in spec. However, if you were to lower the temperature by 10C to 95C, then the minimum guaranteed lifetime/endurance will double to 4000. Lower it another 10C, and that's another 2x increase in lifetime/endurance. So that's why your capacitors lasted so long.

In reality, especially on motherboard, capacitors rarely run near their maximum rated specs, which is why they last much longer than their minimum lifetime/endurance.

Also, since this appears to be the EXACT original part, have they fixed the problem with these so they won't fail again or are these left over stock from the bad batches back in the early 00s?

No, the new batches are all fine. Any Nichicon HM and HN capacitor made after 2005 should be okay (the ones made during 2005 are mostly okay too). You can tell when they were made by their date code, which usually reads something like : H%%$$ where
%% = last two digits of production year
$$ = number of week during that year in which cap was made.

At MIT, I learned that if the original engineer had wanted a 1500uF or an 820uF capacitor, that is what he would have specified in the design.

I agree with that, but classroom and real world experience are two totally different things. I've done a fair share of "daring" recaps too, and all I can say is that most motherboards are quite flexible when it comes to cap parameters.

[theOracle]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

date code, which usually reads something like : H%%$$ where
%% = last two digits of production year
$$ = number of week during that year in which cap was made.

very useful - gracias!

However, the biggest problem is those Rubycon MCZ's your posted the info for are 8 mm diameter whereas the old caps are 10 mm diameter. That means you'll probably have to have the caps sitting a few mm in the air above the motherboard - which generally isn't desirable.

I would partially agree - in VRM applications or any other extremely low ESR applications, lead length is important, but in other motherboard or TV locations, where the ESR is low but not super-low, a couple of mm off the board is fine, and has the added advantage of letting you see whether the solder flowed up to the component side of the joint and made a nice bead around the component side lead.

I have seen many caps from very high end manufacturers sitting a couple of mm above the board from the factory!

[momaka]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

I have seen many caps from very high end manufacturers sitting a couple of mm above the board from the factory!

Yes, in applications where ESR is not critical, you can do this.
Funny thing is I've seen some P4 IBM motherboards do this as well. Not sure why IBM decided to do it that way. But I guess it goes to show you that having the caps right against the board isn't absolutely critical. I've even had to do this myself a few times where I had to fit 10 mm dia. caps into spots meant for 8 mm - and yes, in VRM applications on motherboards.

Another good advantage of sitting the caps a little higher is that if you have hot components nearby or if the copper plane on which the caps are soldered to gets extremely hot due to other components, the long leads will provide some "isolation" for the caps so they won't heat up as much.

[PeteS in CA]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

Another good advantage of sitting the caps a little higher is that if you have hot components nearby or if the copper plane on which the caps are soldered to gets extremely hot due to other components, the long leads will provide some "isolation" for the caps so they won't heat up as much.

With SMT power devices, the voltage planes are indeed used partly as "heatsinks". So if the extra ESR and ESL don't create problems, having a bit of thermal isolation is not a bad trade-off.

[Stevevil]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

Drum Roll please!....
....
SUCCESS! I have restored my GX260 (11 caps this time, whew!).
I was very nervous about this one guys because once I started desoldering I notice that 3 of these were located where there were very fine embossed circuitry all around the post hole. I was so afraid I would spill solder on it or melt the protective cover and short them out. I did discolor two of them mildly but it appears I didn't fry it as the computer BOOTED UP!!!
I've checked BIOS and it seems fine. I booted my Linux based smoothwall OS and it's running!
My soldering is atrocious! I've got silver boogers all over the posts, but when I was done I did a wiggle test on each one and they seemed fairly solid. I had to go back and re-melt one of them to secure it down, but more importantly I didn't damage anything and I got it all back together. I feel so proud. I guess this little high is why you guys do this too.
Or it could be all the flux I inhaled while I slaved 3 hours over this one. lol

Anyways, thanks again guys for all the help. I'm starting to get the hang of this (if only I could improve my soldering ability).
I was using a 40w iron and I'm wondering if that's why I'm having such trouble (it seems you have to really work at it to get the solder to melt, I even have to start high on the iron and bring the "ball" down to the post, that doesn't seem right).
I might get a 60w for my next project.
Anyways, I saved another P4 from the scrap heap and regained a really powerful firewall (replacing my "temporary" 800mhz p3 in the closet).

I'm gonna do a burn in test for a few hours to make sure nothing smokes before I hem it up and put her in operation permanently.

I'm sure you haven't heard the last of me. Take care all!

[mockingbird]

Re: Dell GX-260 motherboard repair... cap appropriateness question.

the Rubycon MCZ is no longer made because it had some issues!

I'm not contending this point, but where did you hear that this was the reason it was discontinued??? I think Rubycon and Nichicon both discontinued the Ultra-Low ESR caps because of the lack of demand given that most manufacturers have switched to VRM designs that use all polymer caps.