Recapping Tutorial - how to replace old, leaky surface mount electrolytic capacitors

hi Leah this video is a demonstration of the recapping process which is basically replacing old capacitors on a printed circuit board with new ones this is the way that I do it I'm not suggesting that the way I do it is better than anyone elses but this is these are the steps that I take whenever I'm doing a recap on any sort of board so a quick overview of the problem electronic devices use capacitors and in particular quite a lot of aluminium electrolytic capacitors now this picture here shows all of these are electrolytic capacitors and the issue with them all of all electrolytic capacitors are basically just a tightly wound scroll of aluminium layers of aluminium foil and in between those layers of paper that has been soaked in electrolyte basically the problem is that as these capacitors get old that electrolyte can leak out of the capacitors the capacitor stopping effective and and the the Gatorade that comes out of them can end up corroding the board so what ends up happening is after a certain period of time you you see the the liquid coming out of the capacitors on the board and then you know that they have to be replaced now what I'm going to be replacing today is a Mac Macintosh classic two motherboard now this is about 25 years old and the pretty much every board that I've ever seen if this vintage does have some capacitor leakage so don't sort of think that you know your your device is going to be and somehow immune to it once they get to a certain age they are going to leak and the capacitors will need to be replaced otherwise the corrosion if left untreated will just mean that your device gets completely and totally destroyed and can never be repaired so there's been a lot of talk about well I have seen some videos where people have talked about just washing the electrolyte fluid off this well you know in some instances give you a temporary solution but it is only a temporary solution and it doesn't always guarantee that's going to fix the problem because although that might remove the electrolyte off the board it's it doesn't repair the the capacitor and so you're going to end up with the device that perhaps doesn't work properly and you're going to probably end up with ongoing leakage as well so it's not just a matter of cleaning that fluid off the board you've you've got to replace the capacitors now what I've got here is I've got you know I'm just going to cross over here to the the microscope but what I've got here is on the left is a surface mount electrolytic capacitor now these are the real problems because so many of these these sorts of devices have surface mount aluminium electrolytic capacitors now on the left is the is the capacitor on the right is that is same sort of capacitor but with the aluminium taking off so that you actually see what oh I was talking about before that you have this this brown stuff which is basically just paper wound up in a little scroll in between that are layers of aluminium foil which you might just be able to see there and this paper is the stuff that's dust in the in the electrolyte and that's where that the leaking electrolyte comes from in order to do a recap what you're going to need a soldering iron a hot air rework station some solder some flux solder wick some fine tweezers some good lighting and good eyes and a steady head are also quite good and of course one of the most important things is is to have replacement capacitors now you can of course just replace your year old aluminium surface mount electrolytic capacitors with new ones or in the instance of what I will be doing here I'll be replacing them with tantalum capacitors that don't leak so another question that you would have to ask yourself would be should I actually do this if you're you know if this is the the first one that you're planning to do and you're not sure about whether this is a job you prepared to take on what I would say about it is you know by all means give it a try but what I would suggest is if your board is in reasonably good condition then I would say that's really the job you would want to take on if you've got one with really bad corrosion or if you've actually got components that are actually falling off the board under those circumstances I would probably recommend finding someone else to do it just because when the board has already sustained that level of damage it would probably help to have someone with a bit of experience to you know in in order to either restore some of those damaged pads on the board or in some instances they would have to be replaced with with new traces so but having said that you know I mean the first one I did was in a terrible state and I still managed to complete it so certainly how the UM the next thing is I'm going to show you this this board under the microscope now I use a microscope because my eyes aren't particularly good anymore but also because it helps me sort of demonstrate the process but this is something that you can do without a microscope you might want to use maybe something like this which is just a lumen ated magnifier something that allows you to get a reasonable sort of view of what you're looking at but it these components aren't that small so so you know I definitely think it's something that you can do without a microscope so let's let's there have a look at this board and as we look around here so here's a little cluster of for surface mount electrolytic capacitors and you can kind of see this corrosion around around here and around here and indeed above it if you have a look here I'm not sure with this board may not have actually been cleaned at some stage but up here you could see all this sort of crusty crunchy stuff here that's all residual fluid that has come out of these capacitors at some stage this really does look like someone has washed this at some stage but not particularly well once I'm finished with the recapping process I will actually clean the board in an ultrasonic cleaner which will help get a lot of this gunk off okay so I am going to replace these four capacitors here I'm not going to go through the process of replacing all of them that would just be too long and boring but I will just go through the process of replacing these four capacitors here and we've got I'm gonna just change the focus up here a bit you'll see that we've got this one here is a 10 microfarad 16 volt another 10 microfarad 16 volt another 10 microfarad 16 volt and then this one is a 1 microfarad 50 volt so before I would do any of this the very first thing I would do is take a photo of the board with the old capacitors on there and make sure when you zoom in on the photo that you can actually see all of the numbers on the top of these capacitors so that when you go to replace them with new ones you could see where they're supposed to go there are there are you know websites with reference information about you know what capacitors go where but you know which you know in certainly in the instances there I've had some boards where the capacitors been so damaged you can't even see the numbers only on them anymore so that's always useful but as I say I just I tended to work with a work from a photo you know of the original board the first step where we're going to take is to remove these old capacitors now there are a number of ways you can do that one of course would be just using a soldiering on but the problem with that is that because they're the capacitors they held on with two separate pins that it's very difficult to apply heat to both of them at the same time so if you're going to use a soldering iron you it sort of have to you know be solder one and then kind of Bend it up and then try and resole or the other and that's not really a process that I would recommend because that's probably going to result in tearing a pad off the board and so I wouldn't recommend doing that you can use solder tweezers where you actually have you know tweezers with sort of heat on both tips of it so that you can melt those sides and then lift it off but I I much prefer to use a hot area rework station and the hot area workstation basically allows allows us to you know sort of just blast very hot air at the capacitors melts both sides both pins and then you can just lift it off now I use a quick 86 one DW a honorary work which is a nice balance between sort of quality and budget but you could do this with one of those real L cheaper ones I wouldn't necessarily recommend it but you could you know do this job these components are quite large and I mean the main problem with the really cheap ones is they generally don't get a very powerful jet of air and really hot air they just don't they don't come up to quite the same temperature and they don't blast as strong a blast of hot air but you know I have used those sort of el cheapo once before and you could do this job with them so I would certainly recommend using that ahead of just you trying to do this with a soldering iron alone so all right so let's move on to the process of actually removing these capacitors so I'll just focus a little bit here now one of the issues that I have going on here is right there right yeah is the the reset button for this computer and that reset button is plastic and so if I hit that with hot air that is going to melt and look unsightly so what I'm going to do is I'm going to put something in between the capacitors and the plastic there that'll help sort of protect the plastic from the heat now I'm using just a flat piece of steel here and this is actually just the blade from a box cutter and one of the things it's really great about these is you know they're they're a decent thickness of metal they're quite good at absorbing the heat but the other is that because in those box cutters they you can snap them off so you can snap them to different lengths and so they're really good for finding one a nice length that'll just slot into the space that you have on the board so here's my little box cutter piece and I'm just gonna slot this in here between the plastic and the capacitors and that will help protect them right so next thing I'm going to do now is remove them now when you apply the hot air what it does is that generally it heats up the board and what that then means is that once that board has heated up the second third and fourth one come off a lot easier in that area so rather than just moving removing one when they're in a little group like this I remove all four at the one time this is just much quicker and easier to do it that way so I'll grab my my trusty hot air yeah and I'll start down here in the corner and I will just apply some heat to there and we can see the plastic starting to melt the plastic on around the capacitor starting the milk and then pop he comes let's go get the next one he comes the next one okay so that's four capacitors just came off really really quickly and easy with the hot air and if we take our little metal off you'll see that that plastic is absolutely and totally intact has not been melted one little bit now if we have a look in underneath where those capacitors were you can see we've got this black crusty stuff going on here and that's that that's that Gatorade that's leaked out of the capacitor onto the board and and that's one of the things you need to do after this is inspect and make sure that we haven't got any damage to any of these traces so this one here you can see this does appear to still be intact I will check for sure to see that that is intact but it does appear to still be intact so I think then once we replace the capacitors there we should be fine so when it comes to putting the new capacitors on I tend to use a soldering on rather than the hot air station and there are a couple of reasons for that the first is that the tantalum capacitors I use orange and when you hit them with hot air they go Brown and it looks ugly it doesn't affect their functionality but it just doesn't look too nice the other reason is control I find that I can get far better control getting the capacitor into a position I want just using a soldering iron and so that's the way I'll do it that way now when it comes to the soldering on I'm using a solder station I'll use a hako soldering station you're not going to want to do this with one of those all-in-one soldering irons you're going to want a proper soldering station one that can yeah I put a reasonable amount of heat the other thing is I use a bevel tip so if we have a look at this under the microscope you look you'll see that the tip has a little as a flat end as a flat in as a flat edge there and I just find it much easier for getting the heat on to what you want then using a pointed conical tip I don't use pointed conical tips at all ever earlier they use different size of bevel tips that's my soldering iron the next thing I use is flux and flux is an incredibly important part of of this of this cleanup process the purpose of flux is to help solder to flow you end up with much better shape of your solder joints if you're using flux with it and I would recommend using it very very liberally now I use mtech NC 5 v 9 v 2 TF I have found a few other ones that work quite well but I quite like the mtech flux it's sort of a gel and this stuff is is like generally no clean so that is that you can put this flux on and you're gonna leave it on there whereas a lot of other fluxes you have to wash off afterwards now I still wash it off afterwards because I think leaving flux on there just makes the board look awful but these are designers are no clean type flux and as I say you want to be really liberal with them because it just you'll just end up with far better solder joints then the other thing is the solar now I use a leaded solder but of course you can use a lead-free solder if you prefer I go we'd let it solder because I like that to work with the lower melting temperature by a good quality solder that's what I would recommend you basically get what you pay for when it comes to solder and so now armed with my soldering iron my flux and most my solder I'm gonna go set about cleaning up these these ugly joints that I've just exposed after removing those those components okay so let's start with this one right here I'm gonna just get some flux onto there and they're here by the looks of it get rid of that here we don't need here there okay let's get some there now I would normally do them all in one go but I'm gonna do just one to start off with just to demonstrate so get some new solder and we just give it a little bit of a rub around like that now as soon as you start doing this with the the new solder in the flux these things generally all start looking wait way better like almost straight away and then the next thing I'm gonna do is use my wick and this has solder wick and this is a sort of a braided copper that has flux on it and it sucks sucks up solder and I use this as you know first of all to remove that new solder that I just put on as part of the cleaning process but then I also use the the flux to you know clean up the pads almost like a sandpaper so I'm just going to grab some of this week I'm gonna put it down on to these pads and I'm just going to gently rub very gently rub in a circular motion okay now what you can see there these those pads basically coming up looking really nice now I'm gonna use a cotton bud or a q-tip with a little bit of isopropyl alcohol probably should have cleared included that into what you will need bit at the beginning shouldn't I bit of isopropyl alcohol and then with my cotton bud or q-tip I'm just gonna rub away all the old stuff I'm getting rid of my flux and I'm getting rid of all my gunk okay now you can instantly see the difference here now here is one of the old scungy black cruddy ones and here is our nice clean fresh one and as you can see it you know virtually looks like brand-new that one is now ready for a new component to be put on so now we just have to go through the same process for these other three so I'm just gonna do these the old flux on there that get our fresh solder do a little circular motion here okay and then we'll grab out sold a week again and just give those a bit of a rub now during that rubbing process you'll see that I'll sometimes take off some of the coating on these traces here and so there now we've now been tinned with with solder the only thing there is to just make sure that because they're now exposed you don't want to you know accidentally create a short buyer when you put the new components on touching some of those exposed wires okay just a little bit more here for the last one let's get yeah yeah still trapped that way there we go that give it a little bit of a rub a little bit of a rub start having trouble just try putting on either more solder or more flux all right so there we've now got four nicely cleaned up pads just cleaning off all the flux and all the black gunk with my cotton bud in alcohol okay and then we have four nice neat and tidy pads ready for the new components to go on there now you can sometimes end up ones with far worse corrosion than I've just shown there and with those ones it can sometimes take a little bit of work to get some of the old gunk off in some instances I've even used like a little scalpel like this little round edge scalpel to scrape off some of the old stuff to reveal the copper underneath but the majority of them will be sort of like this you know it's not too hard to clean up okay so the next thing now is to get the new capacitors put in place now as I mentioned before I have four capacitors that need replacing in this section and they are so we'll look so there are three of them 10 microfarad 16 volt and one is one microfarad 50 volt I'm just going to grab my replacements here so that's 10 microfarad 16 volt times three one two three and one microfarad 50 volt times one now time to show you something which is a little bit annoying and confusing potentially confusing here is no it isn't I dropped it where is it there it is here is a an electrolytic capacitor now what you're see is down one side yeah you've got this black stripe that refers to the negative pin so it's that's basically so did you put these on with the correct polarity if you have a look here these have got they don't plus and minus signs on the board showing what the polarity is so there's your there's your positive there is so that means your negatives gonna be on that side so if we are putting this capacitor here we would be putting it with this stripe on the negative side tantalum capacitors they have the stripe on the positive side so if you're working with a tantalum capacitor you need to make sure the stripe is on the plus side so yeah that's just to add a little bit of extra confusion you just need to make sure that when you're if you're replacing these with tantalum so that your stripe goes on the positive side if you're replacing them with electrolytic so your stripe goes on the negative side all right so this guy here is my 1 that's my 1 microfarad 50 volt which is going into that C 15 location right here the first thing I've got to do now is put some flux onto the pads ready to put the new guy on so flux goes on and then the capacitor goes on top now these tantalum capacitors are a little bit wider than the capacitors they're replacing which means you don't have much pad on either side to work with but that's okay there's you just have to be very careful with the positioning but at the end of the day it still works fine so what I basically do is I now get my soldering iron and I get some solder and I just melt some solder onto the syle soldering on so now at the end of that soldering art has just got a bit of liquid solder on there now I get the capacitor I hold it in position trying to Center it so that I get an equal amount of pad on either side so I'll just put that there like that and then I melt that on now if I give that a nudge you can see it's well and truly held on on one side so I'm just gonna push it down from the top to make sure it's nice and flush with the board and it is quite for it to harden and there we go so that's that one is soldered on one side ready for solder to go on the other side but rather than them do them one at a time because I've got to flip the board around to do the other side what I do is I do all four of them one side and then I flip it over and do all four of them the other side so next thing I need now is one of my 10 micro farad capacitors and I will need that weird the positive on the left-hand side so let's put some flux on the surface ready to go there we go capacitor goes down in position and once again some solder on to the tip of the soldering iron hold the capacitor capacitor in position and Milt okay it slipped a little bit so I'm gonna try and move it back so that I've got room on this side there we go okay now it's not quite flat so I'm gonna there we go so he's flat now and then again just to test give it a nudge you can see that it's well and truly held on on this side but not on this side so there we go move on to the next one and this one here getting positive on the left and this is one another one of the 10 microfarad 16 volt oh I forgot my flux didn't I Fox goes dear why don't I flux this one while I'm at it I set myself a step put that one down there one small bit of solder on the tip hold him still this one's a little bit tricky because I've got my buttons there where I want to help I have my hand okay there we go hold him there do let's there now push him down make sure he's flipped there we go again give him a nudge make sure he's on last one another of the 10 microfarad and I'm going to heat this one here that pluses on the right-hand side you might notice so he's got to be around the other way to the others guess I'm there again solder under the soldering iron apologies to anyone who's listening to this who pronounces solder Sutter it's obviously solder or solder depending on which part of the world you're from I'm from one of the solder parts of the world okay that goes on I'll just again make sure it's flush yes it is and again giving him a nudge he's he's definitely on there so what I will do just quickly here I'm going to just change the focus slightly and if you look at this one you can see you can clearly see that that solder is on the side of the capacitor but it's also going down onto the pad on the board so that one's held in nicely okay next thing we need to do is do the other side so I flipped the board around now a little tip for you if you're ever doing these and you've got a situation where the capacitor is in a difficult to reach position always solder down the easy side first because while you're holding it still if you've got you know better access hold it still do the easy side first and then do the difficult side second okay so let's start with these two here exactly the same process the only difference here is I don't have quite as much room to move because I've got to get in there but it's okay some solder on the tip of it again pushing this down to make sure it's flush melt it onto there like that now I can now give that a nudge and you'll see no matter which side I push you ain't moving so he's on good and solid next one more solder on the end of the soldering iron push it down okay gotta push yep he's on solid everybody here this one again is a little bit tricky cuz I got my button there so I'm gonna probably care I mean it yeah should be fun there I got ring no more solder on to the end of the soldering iron yep and that's on and the last one that I melt my melted my button I'm glad this is my board don't mind melting my own board okay incoming it's from this angle so that I don't melt the button any further there we go and that's really the angle I should have come into this one as well like that there we go but that is for capacitors that I'm now sold it onto the board new capacitors so whenever I put them on I I always do a series of checks after I've done them and they are first of all have I put the right capacitors in the right place so we can obviously double-check that with these codes here when I 6c that is the 10 microfarad 16 volt 105 T that is the one microfarad 50 volt so you just double check against your photo of the where the old capacitors were and you double check those to make sure you've got them the right ones in the right position so that's check number one check number two always check the polarity go over and make sure you stripe is on the positive side strike is on the positive side stripe is on the positive sign stripe is on the positive side very very important then last of all give each one a little gentle push with the tweezers to make sure that they're all on well they're all nice and solid and they're not going anywhere and solar is all soldering is all done so okay so that's those four there they're all is a I'm not gonna I'm not going to demonstrate anymore that's that basically shows the process but you can see now we've got four new capacitors on there I'm now going to go through and replace all of the rest and after that I will go through and show you the cleaning process which is is also very important to get all of that old gatorade gunk off the board and and just gives you much better chance that after the recapping that the board will work so um that's it for this step this is part of the process so there we have it 13 capacitors are replaced and so the next step now is to wash off all the gunk corner for flux and all of the old corrosion that was on this board and I'm going to do that with an ultrasonic cleaner so this is the ultrasonic cleaner here this is distilled water and a special printed circuit board cleaning solution and start loaded in the water and I basically get the board put that into a little basket lower that in I'm gonna give this guy ten minutes on month on ten minutes on the other side then I will show you the process of drying it off okay well the board is out of the ultrasonic cleaner now and it's still got all of the the liquid detergent all over so I need to rinse that off now you could just rinse that in water but I'm actually gonna rinse it in isopropyl alcohol so this is a little bath of isopropyl alcohol drop that inside there and what that does is first of all obviously rinses the board off but the other thing it does is it displaces any water left on it pushes it all out of the looks and crannies so the only the alcohol is left behind and the great thing about acid isopropyl alcohol is it evaporates at a very low temperatures so it means that I'll be able to get this board dry and really fuse much much quicker then if I were to just just settle with water no I'd have to let that dry for sometime what I do to speed up the drying process I actually put these this into the oven so I put this into an oven at about sixty degrees Celsius so it's not particularly hot we're not actually talking about the temperature that would use for sort of cooking any food or anything like that but it's a low enough temperature so that it doesn't melt any of the plastic parts things like these are reset buttons they will melt at quite a low temperatures so as I say put the oven on under that sixty degrees Celsius I then put the board in for around about half an hour sometimes a little bit longer and then after that it comes out completely and totally bone-dry I will then at the end of that process I'll show you the board and show you the difference in looking at some of those areas that had all that crusty gunk on it okay so here is the board clean and dry and recapped and you'll see that a lot of that gunk that was there before has now gone so I'm just moving around here some of the other cap sort of ivory replaced there and these chips here will were the ones that had a lot of you know scones and crunchy stuff between the pins and you can see that's all gone still a little bit of residual corrosion there but basically this is now much much cleaner entirely oh there's another cap there and there's four more caps there and there's the CPU all those pins looking nice this has a pretty good chance of working this is a non-working board there's no guarantee that what I've just done is going to go and fix it but it's certainly worth a try so I'm going to pop its ROM chips back on and and see how it goes okay so this board has been recapped it's been washed it's been dried and now I've connected it up to a power supply to see if it works okay we've got a charm that's a good sign and there we go it's booty now this this classic to analog board desperately needs recapping as well but that's a project for another day I hope there was some information in this video that was of help to someone and thank you for watching

Channel: Branchus Creations

Views: 69,930

Keywords: Macintosh, recapping, vintage, capacitors, leak, electrolytic capacitors, electrolytic, capacitor leak, capacitor leakage, surface mount, soldering, computer repair, vintage mac, diy, surface mount capacitors, surface mount components, old computer, electronics, electronics repair

Id: SjgWo7mj8-w

Length: 37min 46sec (2266 seconds)

Published: Sun Nov 04 2018