Motherboard capacitors - Page 1
Forum section: electronics / repair

author: jimdeane
author_rank: Regular Contributor
timestamp: January 11, 2016, 07:23:05 am
content: 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?

author: Falcon69
author_rank: Super Contributor
timestamp: January 11, 2016, 07:30:40 am
content: 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.

author: Rasz
author_rank: Super Contributor
timestamp: January 11, 2016, 07:45:10 am
content: Quote from: Falcon69 on January 11, 2016, 07:30:40 amhah, was going to write _exact same post_2005 = Pentium 4 = can find them(or better) free at the recycling center of $10 at goodwill

author: wraper
author_rank: Unknown
timestamp: January 11, 2016, 08:48:30 am
content: 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.

author: jimdeane
author_rank: Regular Contributor
timestamp: January 11, 2016, 08:50:15 am
content: 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.

author: dhodapp
author_rank: Newbie
timestamp: January 11, 2016, 11:59:49 am
content: 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.

author: wraper
author_rank: Unknown
timestamp: January 11, 2016, 12:47:01 pm
content: 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.

author: DimitriP
author_rank: Super Contributor
timestamp: January 11, 2016, 01:43:30 pm
content: Close you eyes and ears and go with Option #2Get yourself a solder suckerhttps://www.radioshack.com/products/radioshack-45-watt-desoldering-iron?variant=5717855877and 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 "

author: Ian.M
author_rank: Super Contributor
timestamp: January 11, 2016, 02:29:03 pm
content: 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.

author: AlxDroidDev
author_rank: Frequent Contributor
timestamp: January 11, 2016, 03:19:26 pm
content: Quote from: Ian.M on January 11, 2016, 02:29:03 pmMy 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.

author: Neganur
author_rank: Unknown
timestamp: January 11, 2016, 04:02:23 pm
content: 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.

author: rx8pilot
author_rank: Super Contributor
timestamp: January 11, 2016, 04:02:33 pm
content: 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

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: January 11, 2016, 04:32:42 pm
content: 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 checkouthttp://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 .

author: Cubdriver
author_rank: Unknown
timestamp: January 11, 2016, 04:40:55 pm
content: 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

author: janame
author_rank: Newbie
timestamp: January 11, 2016, 04:44:12 pm
content: 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.

author: wblock
author_rank: Regular Contributor
timestamp: January 11, 2016, 04:51:56 pm
content: 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.

author: Ian.M
author_rank: Super Contributor
timestamp: January 11, 2016, 05:10:39 pm
content: 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

author: dfmischler
author_rank: Frequent Contributor
timestamp: January 11, 2016, 05:17:47 pm
content: 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).

author: edavid
author_rank: Super Contributor
timestamp: January 11, 2016, 05:26:10 pm
content: 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.

author: rx8pilot
author_rank: Super Contributor
timestamp: January 11, 2016, 05:33:51 pm
content: 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.

author: Gyro
author_rank: Super Contributor
timestamp: January 11, 2016, 06:43:22 pm
content: 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.

author: edavid
author_rank: Super Contributor
timestamp: January 11, 2016, 07:17:07 pm
content: Quote from: rx8pilot on January 11, 2016, 05:33:51 pmI 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.QuoteNot 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-/252170396707QuoteYou really don't need to do this.

author: Ian.M
author_rank: Super Contributor
timestamp: January 11, 2016, 07:44:39 pm
content: 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!

author: rx8pilot
author_rank: Super Contributor
timestamp: January 11, 2016, 07:54:09 pm
content: Quote from: edavid on January 11, 2016, 07:17:07 pmSome 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.

author: rx8pilot
author_rank: Super Contributor
timestamp: January 11, 2016, 07:58:28 pm
content: Quote from: Ian.M on January 11, 2016, 07:44:39 pmThat 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.Quote from: Ian.M on January 11, 2016, 07:44:39 pm+++++1

author: edavid
author_rank: Super Contributor
timestamp: January 11, 2016, 08:26:09 pm
content: Quote from: rx8pilot on January 11, 2016, 07:54:09 pmThe board has been working for 10 years, so whatever flux is on there isn't a problem.The OP is not going to be using anything other than rosin flux, also not a problem.There's just no reason to mess with it.

author: jimdeane
author_rank: Regular Contributor
timestamp: January 12, 2016, 12:54:10 am
content: I appreciate all of the opinions and advice. In the end it's part challenge and part fiscal, I would really rather not drop $800+ on a new machine right now. Spending a hundred or so on capacitors and a new soldering station...not so bad.I'd feel better about buying a brand new box if I was confident that I could clone her existing drive to the new machine. I'm guessing even now most modern equipment has Win7 drivers, so that's a cautious 'maybe'. (We really, really do not want to go Win10.)

author: edavid
author_rank: Super Contributor
timestamp: January 12, 2016, 03:08:21 am
content: Quote from: jimdeane on January 12, 2016, 12:54:10 amWhy not buy an Optiplex 745 and a Q6600 for < $50

author: Rasz
author_rank: Super Contributor
timestamp: January 12, 2016, 04:43:03 am
content: Quote from: edavid on January 12, 2016, 03:08:21 ambecause he would really rather not drop $800+ on a new machine!

author: jimdeane
author_rank: Regular Contributor
timestamp: January 12, 2016, 08:22:03 am
content: Quote from: edavid on January 12, 2016, 03:08:21 amWith a used machine I make the assumption that it has been taken care of and doesn't have other impending fatal flaws. If I'm replacing this machine, I will go straight to buying new because then I do not have to deal with someone else's problem.If it were one of my play-around machines, I'd probably do just what you suggest, or something similar. This one is for my wife's business, so I'm not going to go for the middle options. Either I fix this one right or she'll buy a new one.

author: Ian.M
author_rank: Super Contributor
timestamp: January 12, 2016, 08:47:41 am
content: That puts a different slant on it. If its business critical, the down-time to re-cap it then burn-in test with a live CD and a 'scratch' HDD is probably unacceptable. You'd do better to get a spare motherboard and PSU from the same make and model of machine (or even a complete spare machine) and run that while you recap and test the original motherboard. Alternatively, if you have another PC powerful enough to run a clone of the HDD in a VM, that could also buy you the time to do the job right.Chances are the PSU may also be developing bad caps. Suspect small electrolytics on the primary side and all secondary side ones that are immediately after the rectifier diodes. Failure modes can include grossly excessive ripple on the low voltage rails which is likely to corrupt data, or catastrophic loss of regulation which would destroy at least one and possibly more system components.Windows 7 support ends 2020, so if you really want to avoid Windows 10 for as long as possible, its worth putting in the time and money to get the spares you need before they become totally unobtainable.

author: AlxDroidDev
author_rank: Frequent Contributor
timestamp: January 12, 2016, 11:11:40 am
content: Quote from: Ian.M on January 12, 2016, 08:47:41 amPossible, but not a problem directly related to the bad caps on the mobo. Besides, even if it has, chances are the PSU uses a single sided board, which makes changing components a breeze (I've done it a lot).My 2 cents: I'd try and fix the board. If it's done carefully, the OP has high chances of success. Besides, fixing the board is "environmentally correct", FWIW.

author: Ian.M
author_rank: Super Contributor
timestamp: January 12, 2016, 12:09:30 pm
content: I was just pointing out that downtime on a business PC running critical applications you don't have a hot spare for is far more costly than on a personal/hobby PC.I agree its worth a shot at fixing the board and that early stage bad caps in the PSU wouldn't contribute to the caps on the board failing.. However it would be a great disappointment if a failing PSU took the board out in a few months time so the PSU should be checked as well.

author: Johnny10
author_rank: Frequent Contributor
timestamp: January 14, 2016, 03:30:42 pm
content: If this is a critical component in your wife's business.A new machine makes far more sense.But if it is an exercise in your learning/experimenting can do attitude go for the capacitor change.My own experience on what I thought would be easy to do repairs with all my latent skills. And unlimited budgetHas ended in destroying delicate pads and disturbing surrounding components, Hours wait make that days of searching out components, learning the purpose and design of non-working circuits. Ordering new parts.It can be overwhelming, but my curiosity always wins in the end and I keep at it until I find the solution. 60 hours later!The amount of experience and knowledge the members have on this site...It is worth taking their advice.

author: rx8pilot
author_rank: Super Contributor
timestamp: January 14, 2016, 07:18:25 pm
content: I do a lot of repairs that are financially unjustifiable. They can be fun and land me some useful skills that I keep forever. Those skills can become VERY valuable on the day that something MUST be fixed.I got an old/crusty pick and place machine off eBay about 10 months ago. Totally useless if I was not able to repair a ton of problems. Those repair skills came from all the other repairs and attempted repairs I have done in the past.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: January 14, 2016, 08:12:20 pm
content: Same here , theres almost never a reason to not try to fix stuff , if for no other reason learning .I've made a living in ,Union carpentryAuto repairWeldingGold miningGun smithingMachiningPlumbingElectrical res. & com.Electrical appliance repairTower work ham radio & comm.My main leaning point now is electrical / RF repairAnd if it doesn't get fixed , then I fill my empty time with scrapping

author: brillopad
author_rank: Contributor
timestamp: January 17, 2016, 01:03:57 am
content: Quote from: Neganur on January 11, 2016, 04:02:23 pmOften easier to rip the olds caps off and use the exposed legs to solder on the new cap.

author: John_ITIC
author_rank: Frequent Contributor
timestamp: January 17, 2016, 01:15:01 am
content: Funny, I just spent a week chasing down my instability issues of my old server motherboard (P4 Abit TH7II-RAID). The system crashed seemingly randomly. MemTestx86 passed fine but I traced down the issue to leaking caps around the RDRAM DIMMs. They looked exactly like your caps. Slight crustiness but no major leak. In my case, I've had that computer for 15 years and have hundreds of applications installed. I also have SCSI cards and a SCSI backup station. Moving to a new computer is a big pain in the neck so I wanted to get this box working reliably as cheaply as possible.The solution was to replace only the caps that clearly were leaking (around the RDRAM). Other caps around the P4 looked a bit bulged but were fine. I managed to de-solder and solder only with my Hakko 936. A better approach would be to pre-heat the board but I wanted to try the quick and dirty way first and it actually worked. The machine is now up and running reliably again.I measured the capacitance of the removed caps to about half the rated capacitance.Sometimes the hardware cost is a minor cost of the system...

author: TheSteve
author_rank: Unknown
timestamp: January 17, 2016, 01:44:25 am
content: Quote from: John_ITIC on January 17, 2016, 01:15:01 amIf I found bulged caps I would have swapped them out while I had the board out being the machine is so important to you.

author: Cubdriver
author_rank: Unknown
timestamp: January 17, 2016, 04:33:13 am
content: Quote from: TheSteve on January 17, 2016, 01:44:25 amAgreed - the bulging ones are on borrowed time - I too would change them before they crap out completely.If nothing else, order spares so you have them on hand when the time comes...-Pat

author: Nerull
author_rank: Frequent Contributor
timestamp: January 17, 2016, 07:59:54 am
content: Quote from: jimdeane on January 12, 2016, 08:22:03 amRead what you just wrote, and then think long and hard about the potential damage you're about to do to this motherboard and still use it it still works afterward. The worst care anyone could possibly take of their equipment, could not compare to what you're about to put the board through. That doesn't mean it won't work, but if you think this procedure is risk free you're nuts.You're spending $100+ to save $10.

author: nctnico
author_rank: Super Contributor
timestamp: January 17, 2016, 08:04:03 am
content: Quote from: wraper on January 11, 2016, 08:48:30 am15W isn't going to cut it. You'll need 80W + hot air at least. The only way to get these capacitors from the motherboard is pre-heating with hot air and then quickly (before the board cools down) remove the solder with solder-wick once the capacitor has been removed.I have a similar Dell system which needed the capacitors replaced twice over the years. I guess the on-board PSU puts too much ripple current through the capacitors.

author: wblock
author_rank: Regular Contributor
timestamp: January 17, 2016, 04:09:05 pm
content: Quote from: Cubdriver on January 17, 2016, 04:33:13 amBulging caps have already failed. They might show full capacitance, but the ESR increases and they aren't removing the ripple they are supposed to. The other caps in parallel have to deal with that increased ripple, and they are likely near failure too. Or already failed, they don't always fail visibly.

author: rx8pilot
author_rank: Super Contributor
timestamp: January 17, 2016, 07:58:37 pm
content: Quote from: nctnico on January 17, 2016, 08:04:03 am+1You can't fake it IMHO.

author: John_ITIC
author_rank: Frequent Contributor
timestamp: January 17, 2016, 11:50:06 pm
content: Quote from: wblock on January 17, 2016, 04:09:05 pmNote that many capacitors have a slightly non-flat upper surface, even as new. I would have replaced all the caps but I didn't have the correct ones in stock. After replacing the bad ones, my board works fine and the voltages are good. If the board acts up in a few years again, then I'll deal with that then. Way too many other fish to fry at the moment.

author: nctnico
author_rank: Super Contributor
timestamp: January 18, 2016, 02:58:51 pm
content: Values which are near enough will also work. The Dell machine I mentioned earlier was my server and it crapped out just weeks before it was scheduled to be replaced so I had to make do with what I had in stock.

author: jimdeane
author_rank: Regular Contributor
timestamp: February 01, 2016, 09:14:26 am
content: I have a couple of other boards to practice on now, and will have a hot air station and a Weller or Hakko temp controlled soldering station by the time I start. In the meantime she is on my good laptop, which is my motivation.I'm wondering about capacitor selection. I have cataloged the caps on the motherboard, and will be replacing all of the KZG caps. I've been looking at various manufacturers and series, and I have a question.I am reasonably sure that having a higher impedance would be unacceptable, but can the values go too low too? I see the KZG 820 is listed at 36 milliohm and 1140 mA rated ripple current. The Nichicon E-HN 820 is rated at 21 milliohm and 1300 mA. The E-HM is a bit closer to the original KZG rating at 30 milliohms and 1140 mA.Should I prefer the E-HM over the E-HN due to the closer specs?

author: Srbel
author_rank: Frequent Contributor
timestamp: February 01, 2016, 11:05:16 am
content: If you go to low, you may end up with similar problem:https://www.eevblog.com/forum/repair/atx-smps-%28tl494%29-output-oscillating/msg800272/#msg800272:/

author: dfmischler
author_rank: Frequent Contributor
timestamp: February 01, 2016, 01:58:25 pm
content: Quote from: jimdeane on February 01, 2016, 09:14:26 amIt might not make a difference. As an anecdotal data point, I replaced the United Chemicon KZG 820uF caps with Nichicon HM 820uF caps on a half dozen boards and have had no further problems with them.

author: tjg79
author_rank: Contributor
timestamp: February 01, 2016, 08:50:10 pm
content: Check out the Bad Caps Forum:http://www.badcaps.net/forum/They sell caps also. They may have a kit for your board.I don't listen to the naysayers. If you have a bad cap problem, it can be fixed. If you've never done it before, then you get a chance to learn a new skill. You'll get a lot of good help on the bad caps forum.You can also price caps at Mouser Electronics and Digi-Key Electronics. I find that Mouser usually has the better prices.Do you have a good soldering iron? I use a Hakko FX-888D. You can get one for about $100.00. Get a $5.00 solder sucker and some good quality solder wick. Stay away from the Chinese crap. For solder, I recommend the Kester 44 Rosin Core .031". You don't want lead-free solder. You'll need a flux pen as well. There are many videos on YouTube that demonstrate good soldering techniques. Everyone into vintage electronics, old computers, or likes to fix electronics should have these tools. They pay for themselves after a few projects.I also recommend an ESR meter. I like and have a Peak Electronic Design Atlas ESR+ ESR70. It's a very handy tool to identify bad caps in circuit. Not all bad caps have the usually bad cap indications of bulging, swelling and leaking. Some look good until you test them with an ESR meter.RegardsPSI also recommend some 99.9% IPA and a camel hair brush. You can price all these items out on Amazon.com.You want to be very careful and not pull a cap that hasn't been adequately desoldered or had all the solder melted. You can damage the PCB traces and through holes if you get in a rush. Take your time and let the caps fall out.You don't need hot air to replace electrolytic caps on a motherboard.

author: Johnny10
author_rank: Frequent Contributor
timestamp: March 03, 2016, 04:03:37 pm
content: How did this repair eventually work out ??

author: MyHeadHz
author_rank: Regular Contributor
timestamp: March 04, 2016, 07:30:00 am
content: Quote from: Falcon69 on January 11, 2016, 07:30:40 am

author: jimdeane
author_rank: Regular Contributor
timestamp: June 20, 2016, 04:35:22 am
content: Quote from: Johnny10 on March 03, 2016, 04:03:37 pmSorry, forgot to come back and update.After acquiring the Weller WES-51 soldering station and some supplies, I went through and replaced all of the questionable KZG capacitors, including the three 820 uF ones that had visibly failed. I used 63/37 multicore solder, and a solder sucker to pull the excess solder from the through holes. I replaced the 820 uF caps with Nichicon UHM0J821MPD.On a couple of the caps I had to work on them a while to get them to pull through the board, but not terribly bad. I added flux and fresh solder before pulling and that helped a lot.Computer runs like a champ. Problem is my wife got used to my Core i5 laptop serving as her desktop computer, so we will probably end up upgrading in the next year anyway. Still, nice to have it functioning until we have a plan to replace it.

author: knks
author_rank: Regular Contributor
timestamp: July 07, 2016, 12:35:42 am
content: I usually clean the holes by drilling them. Solder is very soft. Never had any issues, however not sure if it can be used for multi layer boards