Motherboard capacitors

[jimdeane]

My wife's trusty Dell e510 (about 10 years old) suddenly began having issues last week and then crapped out completely a couple of days ago. This is a machine we specced out and purchased in late 2005, and we went with higher end components and expandability.  Consequently, this originally 1gb ram WinXP computer is now a 4gb, 1TB+ Win7Pro64 computer and runs that OS with excellent speed.

Well, at least until this week. Now it boots, but then errors out with video artifacts and then shuts down within a couple of minutes.

I booted Ubuntu on a USB drive to recover data and...ooh, look, video artifacts.  Crap. I took it out of service and started checking. After verifying the power supply was putting out the expected voltages, I removed the memory and cards and did a visual inspection of the components. Hmm.  Bulging and vented electrolytic capacitors. (See attached photos.)

I do not see any significant corrosion or damage to the board itself, the caps seem to have vented only at the top. Upon close inspection, there are only three bulged cans, two of which have vented. All three are identical, 820 microfarad. I have not fully inventoried the board, but there are at least some other identical caps which have not vented.

So, I'm going to try my hand at replacing these. I have nothing to lose, and I hate to replace a computer that is still completely meeting our needs.

It seems I have several options.

1. Complete re-cap. All failed and nominal caps replaced. Pros: can replace all with good caps. Cons: nearly 50 caps to replace, which is about 15x the chance of screwing something up.
2. Partial re-cap #1: Replace all failed caps and caps that are identical to the failed cap. Pros: Decent chance of ferreting out caps that are 'about' to fail. Cons: Most old caps left in place.
3. Partial re-cap #2: Replace all failed caps.  Pros: Probably fixes board, less expensive, less chance of screwing something up. Cons: May leave short-time-to-fail caps in place.


So...thoughts?  Should I consider a limited distilled water rinse to remove any aerosolized electrolyte that settled on the boards? Do I finally need to bite the bullet and buy the WES(D)-51, or can the 15w pencil iron I have used for nearly everything I've ever put together or repaired (from radios to Arduino shields) handle the task with a reasonably delicate touch?

[Falcon69]

Sadly, to be honest, for the price you spend on new caps, solder wik, solder, Wife yelling "You done yet?'....You could buy aworking one with same or better specs off ebay or craigslist.  Salvage what you can off it for later if you want, but buy a new one.

Soon, You'll have to transfer to windows 10. Microsoft is soon going to force everyone to do so, and that motherboard I doubt could run it.

[Rasz]

Sadly, to be honest, for the price you spend on new caps, solder wik, solder, Wife yelling "You done yet?'....You could buy aworking one with same or better specs off ebay or craigslist.  Salvage what you can off it for later if you want, but buy a new one.

hah, was going to write _exact same post_
2005  = Pentium 4 = can find them(or better) free at the recycling center of $10 at goodwill

[wraper]

Those should be KZG series which had problems. Pretty safe to replace just 3 of them. 15W firestick very likely will be too weak but you can try, most likely will need to wait until it heats up after every joint.

[jimdeane]

If we buy new we do the same thing again -- purchase something with a high performance/price ratio, decent specifications, and upgradeable. One problem is neither of us want Windows 10, and she has software she uses for her business that I doubt i could easily push to run on Ubuntu.

There's no need to care what Microsoft's opinion is on Windows 7. We own it and can keep using it if we want to. It's behind my home network and we use third party system protection. The machine does what my wife wants it to do for her business and would prefer to keep it rather than buy a new one.

Finding a replacement motherboard is a crapshoot, this model was probably all made before the capacitor plague was remedied.

So the only question that remains is what level of re-cap I should choose. Replace only failed caps, replace all KZG caps (brand that includes the failed ones), or replace all 50 caps on board.

[dhodapp]

Definitely check the other caps for leaked electrolytic fluid even if they aren't blown or bulged. I would probably go with the second option and maybe any caps that are near components or areas that get relatively hot. They usually go out first in my experience. I would also rinse it or at least wipe it down with some rubbing alcohol. As for the iron, you probably want to get something a bit better than a 15W, I myself usually use a 40W but I've been meaning to upgrade to one with temperature feedback which is quite important in getting a good solder joint.

[wraper]

There is no point to replace all of the caps an this outdated motherboard, it's just financially stupid and requires a lot of labor. Moreover Nippon(united) Chemi-con KZG series were defective by design, so there is no doubt they should die eventually. The issue in not because of the excessive heat in particular areas. As a reminder, they should be replaced with LOW ESR capacitors with max ripple current specification not worse than original ones had.

[DimitriP]

Close you eyes and ears and go with  Option #2   

Get yourself a solder sucker https://www.radioshack.com/products/radioshack-45-watt-desoldering-iron?variant=5717855877

and have at it.

Beats having to  fork out $ for a new machine AND having to reinstall everything etc etc etc etc etc etc etc etc are you done yet....etc etc "

[Ian.M]

Depending on the board design (thermal relief on pads connected to copper pours and wide tracks) and the quality of the 40W iron or solderstation, you may have problems. A Weller 100W solder gun or similar will do the job if used with extreme care to avoid pad damage, otherwise you need a genuine Metcal or similar quality solderstation.  Braid and suckers don't work well clearing holes in buried power planes. After removing the cap, if you cant clear the hole, you may do better pushing a lightly oiled steel needle (mounted in a wooden handle) through the hole, while heating it from whichever side has the most copper round the hole. Wiggle the needle gently to keep the hole open as it cools.

I'd go with option 3, at least until you see how much trouble its going to be to do.  Replace *ALL* caps that show *ANY* signs of distress.   I wouldn't worry too much about aerosol contamination from caps that have vented at the can end, but if any have vented at the base, you need to clean all the electrolyte off the board: Foam cleaner and a well wetted wooden handle natural bristle brush to scrub with (No ESD!), distilled water rinse then two IPA rinses and warm air drying.

If it goes well, consider replacing caps that are likely to be highly stressed - e.g. in areas of the board that are likely to run hot, or where there are a lot of large caps in parallel (as that's a common way of coping with more ripple current than a single cap can take)

Unless a board has known bad brand caps from the fake electrolyte formula era, blanket recapping is for fools and suckers.  If it was a quality board, it will only need selective recapping and if its cheap and nasty, it isn't worth the parts and labour to 'shotgun' all of them.  As its for your own use, not a customer, you can always rework it again if you have to.

[AlxDroidDev]

I'd go with option 3, at least until you see how much trouble its going to be to do.  Replace *ALL* caps that show *ANY* signs of distress.

My opinion too.

Keep in mind that removing PTH components from a multi-layer board (like a motherboard) is a royal PITA. Sometimes there seems to be an infinite amount of solder in the holes! I suggest you use a good solder sucker and some solder wick.

Remember not to keep the soldering iron on the board for too long, or you might damage nearby components, specially some SMD components in the vicinity of the cap you're working on.

I've had good experience working with a Dremel Versatip (aka Dremel 2000) on multi-layer boards. Just use the hot-air tip and the medium temperature setting.

[Neganur]

Since it looks like you'll try to desolder the caps.

Forget about wick until you actually have the caps removed from the board. Also, a sucker may not do the trick either, there is plain silly heat sinking capability in those multilayer boards. Drown the leads in extra (fresh) solder usually helps a lot.

[rx8pilot]

Pre-heat the pcb if at all possible. Makes the process MUCH easier and less likely to damage anything.

Sent from my SAMSUNG-SM-G890A using Tapatalk

[KD0CAC John]

I did not catch your soldering experience & equipment , so can be sure of recapping being a viable option , but it could be good practice learning & opportunity .
You should checkout   http://www.badcaps.net/   lots of times you can give the model info of computer , TV etc. and get a complete kit , also info on upgrades etc. , also a forums group .
 

[Cubdriver]

I'd give recapping it a shot.  Replace the failed ones to start, and see how it goes.

I'd also consider this a good excuse to get a better iron - the WES(D) 51 or something similar, along with a good solder sucker (something like an Edsyn Soldapullt, available from Amazon - get the real one, not a knock-off).  The good thing is that the caps you need to replace are two-leaded parts, and can thus typically be fairly easily 'walked' out of the board by alternately heating the leads while rocking the part back and forth to pull the heated lead out of the board.  Once the cap is removed, use the solder sucker and/or wick to clear the residual solder from the holes and install the replacement part.

Good luck with it.

-Pat

[janame]

FWIW, a few years ago, I had a 24" LG monitor start taking longer and longer to turn on until it finally wouldn't turn on at all.  I found, like you did, a couple of clearly failed caps along with others that looked fine.  I just replaced the 2 that were bulging.  It is still working fine, years later.

That motherboard is pretty old, though, like others have said, so I'd only work on it if you just want a little "can I do this" project or something.

[wblock]

As others have said, this board is far beyond economic repair.  But if you are determined to try, start with removing one failed cap.  Use every trick available, adding flux, lead solder, preheating if possible, carefully trying to get the solder to melt without removing pads.  Motherboards need lots of heat due to the many layers conducting it away so fast.  Vigorously casting aspersions on the lineage of everyone involved in every step of the capacitor and motherboard supply chain will not hurt.  This can also be seen as an opportunity to justify a better soldering iron.

After successfully removing one cap, clean out the holes.  There are tricks here, too, like melting the solder and pushing a steel pin through the hole.  Of course, that needs lots of heat also.

Identify the failed cap (locate the spec sheet) and find an appropriate replacement which is compatible in ESR, ripple, diameter, height, and lead spacing.  Motherboards sometimes use skinny, tall caps that are difficult or impossible to buy.  Order these replacement caps, because it's certain nobody local will have them.  Realize that small quantities of quality low-ESR caps can add up in price to a significant fraction of the price of a modern motherboard with solid polymer caps.

Decide whether it is worth replacing at least all of the failed caps on that board.  Really, the minimum should be replacing all of the ones that are the same series as the failed ones.  The ones that are still working are dealing with more ripple, and are probably already close to failure.

If you decide to do it anyway, please post progress reports.

[Ian.M]

http://www.chipquik.com/  Low melting point alloy.   Its <expletive> $expensive$, but when you absolutely *MUST* save the board and conventional desoldering isn't getting the component leg free, it can save your day.   

On the economic viability issue - a used replacement is a gamble.  New - well you wont be able to reuse much except the storage so that's a big hunk of cash.  Then there's the time to reinstall all the application software, upgrading or replacing whatever is incompatible.  Partial recapping makes more sense if you cost in that time and software upgrade costs

[dfmischler]

I have both Hakko and Weller temperature controlled soldering irons.  Unless you are a soldering god you will not get this done with a 15W iron.  I generally use the ChipQuik low temperature solder for recapping because it makes the job as easy as possible.  The hardest part of the recapping job is usually clearing the holes after removing the old caps.  I have worked on a few boards where I simply could not clear the holes with the equipment I have, but did manage to walk the new capacitors into place (shorten the leads before you start, and don't make them exactly the same length).

[edavid]

This is a Pentium 4 system, right?  If I were you I'd get a newer LGA775 Dell system with a decent CPU like a Q6600 or Q9300.  You should be able to boot your existing OS drive and install the new drivers (clone it first to make sure).  You can have a nice upgrade for maybe $50.

But, if you do want to replace those caps (which is not very hard), I would find a scrap motherboard to practice on first.

[rx8pilot]

Its an advanced job. It's is a great learning experience if that is what you are after.

If I needed to do the same thing, I would pre-heat the board slowly. By pre-heat, I mean hotter than you can touch with your hand - around 150C. Add a little solder to each pin of one cap. Use a hot air pencil or similar to add local heat to the pins of the cap until it is loose. The pre-heating method has to be continuously added since the PCB will be cooling quickly. DO NOT pull the caps, they should nearly fall out. Even a gentle pull will lift pads and even cause internal damage. I use Kapton to shield the adjacent parts from the full heat.

Once the cap is out, the holes will likely back fill with solder. While it is still hot, add some flux and use high-quality wick to get the hole cleared. I have also used a very small tip on my hot air pencil with a solder vacuum on the opposite side.

After you have the cap out and the hole cleared, you need to clean all the flux mess up with swabs and flux remover or IPA.

I have a pile of soldering and re-work equipment and thousands of hours of experience soldering since the early 80's. This job would use all my toys and all my tricks. That is not to say it is not worth trying, just keep your expectations reasonable. One damaged trace or an adjacent component/connector cooked and the project is all over.

[Gyro]

Just a hint - there's no point in trying to remove 2 leads at the same time, the cap is dead anyway so destroy it (pushing it over at 90 degrees to the pins should do it) and there should be enough left on each pin to grab while you heat it.

[edavid]

DO NOT pull the caps, they should nearly fall out. Even a gentle pull will lift pads and even cause internal damage.

I find that motherboard caps are much too tight to fall out, they need a firm pull.  I haven't ever damaged a motherboard by pulling a cap lead out though.

Once the cap is out, the holes will likely back fill with solder. While it is still hot, add some flux and use high-quality wick to get the hole cleared.

Not necessary, just use a toothpick or a straight pin.

Or you can get fancy and buy:  http://www.ebay.com/itm/8Pcs-Desoldering-Capacitor-Pin-Repair-Tool-Flux-Stainless-Steel-Hollow-Pin-/252170396707

After you have the cap out and the hole cleared, you need to clean all the flux mess up with swabs and flux remover or IPA.

You really don't need to do this.

[Ian.M]

Also, I'd be reluctant to preheat the board past 125 deg C. You are going to have to hold it at temperature for quite some time while you work and 150 deg C vastly increases the risk of damage to semiconductors, other electrolytics, connectors and other heat sensitive parts.

I wouldn't try to destroy the cap by pushing it over - if it wont walk out by alternately melting the two joints and rocking it away from the pin you are heating, get a better iron or ChipQuik.  If you have to destroy a component to desolder it pin by pin, you need to do so without mechanically stressing the board, which for a cap means peeling the can, but that's horribly messy and is an absolute last resort.

If you've got a scrap motherboard you can practice on, its a big help!

[rx8pilot]

DO NOT pull the caps, they should nearly fall out. Even a gentle pull will lift pads and even cause internal damage.

I find that motherboard caps are much too tight to fall out, they need a firm pull.  I haven't ever damaged a motherboard by pulling a cap lead out though.

Once the cap is out, the holes will likely back fill with solder. While it is still hot, add some flux and use high-quality wick to get the hole cleared.

Not necessary, just use a toothpick or a straight pin.

Or you can get fancy and buy:  http://www.ebay.com/itm/8Pcs-Desoldering-Capacitor-Pin-Repair-Tool-Flux-Stainless-Steel-Hollow-Pin-/252170396707

After you have the cap out and the hole cleared, you need to clean all the flux mess up with swabs and flux remover or IPA.

You really don't need to do this.

Some of what I write is opinion. The opinions are based on a few decades of professional production and re-work of very high value PCB's. It's an opinion, but a solid one.

I rarely, if ever, use pokers to clear holes on multi-layer PCB's. I have used hot air and vacuums in addition to solder wick. The goal is to reduce the risk to near zero for me.

Cleaning is part pride and partly practical. Depending on the flux used, the gunky residue can be chemically active and cause corrosion. It can also be somewhat conductive. In a high-speed board, it can cause problems. If not today, possibly later. Possibly never. Why not clean it and never worry about it? I take a moment to conceal the evidence that the PCB has been repaired for pride purposes, but it also helps. I just the other day repaired a few feeder on my pick and place machine that were damaged from flux corrosion that was not cleaned up.

The caps never really fall out - I said nearly fall out. I put enough pressure to be able to detect the moment when the solder is fully melted. At that point, you have to overcome the friction between the pins and the hole. Pulling while you wait for the solder to melt is a risk. The problem is that the solder does not melt in an instant and you end up pulling on the last area that melts.

If you are able to reach the pins and clip it off, go for it. One pin at a time is much easier. Most caps are flush and bending them over can and will break the PCB.

[rx8pilot]

Also, I'd be reluctant to preheat the board past 125 deg C. You are going to have to hold it at temperature for quite some time while you work and 150 deg C vastly increases the risk of damage to semiconductors, other electrolytics, connectors and other heat sensitive parts.

That is probably true. It's also a guess to know what temp the PCB really is, I don't use thermocouples or anything, only estimate as best I can.

If you've got a scrap motherboard you can practice on, its a big help!

+++++1