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How do you remove smd electrolytic caps?

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    #41
    Re: How do you remove smd electrolytic caps?

    Laptop chargers are usually ultrasonically welded together. They are not made to come apart. A stanley knife down the seams carefully to open.

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      #42
      Re: How do you remove smd electrolytic caps?

      I'll give it a try next time I run across the issue, thanks Diif.
      -- Law of Expanding Memory: Applications Will Also Expand Until RAM Is Full

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        #43
        Re: How do you remove smd electrolytic caps?

        I use one microsoldering pen and when I feel the joint is already melted, I add soldering pistol to the other joint. When it looses I just push the cap away
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          #44
          Re: How do you remove smd electrolytic caps?

          The best way I've found so far was to add some fresh solder to the joints, then use two irons to heat both leads at once and just push the capacitor off the board with the irons, once the solder melts.

          Hot air didn't work well at all.
          "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
          -David VanHorn

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            #45
            Re: How do you remove smd electrolytic caps?

            Yeah well I only have two same 150W transformer irons, so I prefer microsoldering pen and only pistol as a second. If I had two same microsoldering pens, I'd use those simultaneously
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              #46
              Re: How do you remove smd electrolytic caps?

              For me, the problem seems to be the grounding plane. It always seems to act as some sort of heatsink and I can only seem to remove them using hotair and a preheater to warm the board up.

              I have this problem with certain through hole caps as well on newer motherboards I've noticed. It's a real pain. I've tried using a 120-watt iron. My digital soldering station can handle two 120 watt irons or one 200-watt iron. Maybe if I purchased a 200-watt iron for it, I'd be able to remove them with just the iron?
              -- Law of Expanding Memory: Applications Will Also Expand Until RAM Is Full

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                #47
                Re: How do you remove smd electrolytic caps?

                Using any microsoldering pen for such task is just plain stupid. I wonder why so many ppl just can not get the point it won't work. Yeah maybe with twice the needed power you will be able to get some of the heat to the very tip. Cause that's the problem with these micro things, ya know? You need the heat to get from the element to the tiny and thin tip. Guess what happens when you touch something cold (with low thermal resistivity) with it…

                Get some decent 100-125W transformer iron and be done. The trick of this thing is that most of the heat appers exactly when you need it to. So if you really have some decent one (not with laughable secondary winding thickness) 100 W is just enough to solder almost all motherboards. I got 125W one and I can solder PSU cables with it
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                  #48
                  Re: How do you remove smd electrolytic caps?

                  Through-hole capacitors and big copper fills on layers they're connected to will eat heat like crazy. I have also found that I often need to preheat with hot air. Then I use a desoldering gun.
                  "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                  -David VanHorn

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                    #49
                    Re: How do you remove smd electrolytic caps?

                    Originally posted by Behemot View Post
                    Using any microsoldering pen for such task is just plain stupid. I wonder why so many ppl just can not get the point it won't work. Yeah maybe with twice the needed power you will be able to get some of the heat to the very tip. Cause that's the problem with these micro things, ya know? You need the heat to get from the element to the tiny and thin tip. Guess what happens when you touch something cold (with low thermal resistivity) with it…

                    Get some decent 100-125W transformer iron and be done. The trick of this thing is that most of the heat appers exactly when you need it to. So if you really have some decent one (not with laughable secondary winding thickness) 100 W is just enough to solder almost all motherboards. I got 125W one and I can solder PSU cables with it
                    I use the micro-soldering iron for a lot of SMD type components, to try and prevent that thermal shock or whatever it's called, but with certain motherboards, I have trouble with through holes with my 120-watt iron. Maybe if I try like Agent24 suggests I'll have better luck?

                    I think Agent24 nailed the problem I was trying to describe. Soon, we'll have our BGA rework station hooked up in the new house and that'll make a lot of repairs a heck of a lot easier. I can hardly wait. It seems like it's taking forever! NYSEG (the electric company) told us to contact this inspector. We did that. It took him about a month before he contacted us again (he's real busy I guess). He told us he contacted NYSEG and the NYSEG lady will call us. I think we're going to give her a call just in case she forgot. Everything has to be kept up to code and things that were once allowed aren't allowed anymore. The wire from the pole is too close to the neighbors garage roof and the wire runs through an old crab apple tree, which I guess isn't allowed anymore either.
                    -- Law of Expanding Memory: Applications Will Also Expand Until RAM Is Full

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                      #50
                      Re: How do you remove smd electrolytic caps?

                      Preheating to only remove couple THT caps is pretty much overexcessive when all it takes is good enough transformer soldering gun. All the point of this is to work with BGA or large SMD devices, not two-leg caps…
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                        #51
                        Re: How do you remove smd electrolytic caps?

                        Originally posted by Behemot View Post
                        Preheating to only remove couple THT caps is pretty much overexcessive when all it takes is good enough transformer soldering gun. All the point of this is to work with BGA or large SMD devices, not two-leg caps…
                        I think my soldering station should be more than adequate for removing the through-holes, but some of them are extremely hard to get out, especially around the VRM circuit, even with hot air. The board just seems to act as a giant heatsink. The only way I've been able to remove those ones are with hot air and by preheating. 120-watt iron is a decent sized iron. I can go up to 200-watt but I don't see it making much difference with those tough ones. It's a lot of newer boards that seem to be built this way for some reason or another...
                        -- Law of Expanding Memory: Applications Will Also Expand Until RAM Is Full

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                          #52
                          Re: How do you remove smd electrolytic caps?

                          Ambient temperature of the room can make a big difference on boards like that, too.
                          "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                          -David VanHorn

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                            #53
                            Re: How do you remove smd electrolytic caps?

                            Originally posted by Spork Schivago View Post
                            Whatever, I think I've explained enough why any micropen will never work properly for this. Those who want to get the message did, those who don't, won't and continue with this charade instead…
                            Last edited by Behemot; 04-21-2017, 03:49 AM.
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                              #54
                              Re: How do you remove smd electrolytic caps?

                              Originally posted by Behemot View Post
                              Whatever, I think I've explained enough why any micropen will never work properly for this. Those who want to get the message did, those who don't, won't and continue with this charade instead…
                              Maybe there's some misunderstanding? I know personally, at least, I never argued the point that a micro-soldering iron would work for through-hole components. I'm not saying you couldn't use one in certain circumstances, but why would you? They're not designed for through-hole, they're designed for SMT....

                              I was just talking about soldering in general there. I don't think anyone even makes a 120-watt micro-soldering iron, do they? I've always seen them around 40-watt or somewhere in that area....

                              I was saying with my non-micro-soldering 120-watt Weller iron, I cannot physically melt the solder with certain through-hole components and I think with those types of components, hot air and a preheater is necessary.

                              I don't think anyone was arguing with you about the micro-soldering irons and through-hole components, unless I missed something somewheres. You made a valid point and it just made me think about the non-micro-soldering irons and how some components just don't seem removable. Sorry if I offended you or something, that wasn't my goal.
                              -- Law of Expanding Memory: Applications Will Also Expand Until RAM Is Full

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                                #55
                                Re: How do you remove smd electrolytic caps?

                                Originally posted by Agent24 View Post
                                Ambient temperature of the room can make a big difference on boards like that, too.
                                I didn't know that. I'm going to see if I can find some more info on this. Granted, I don't think it's the ambient temp that causes those nasty buggers to not come out. I noticed when I cranked my WX2 up to the highest temperature it could go and I used the 120-watt iron, the actual board would get hot, but the solder still wouldn't melt. To me, that says that copper plane there is acting as some sort of heat sink and absorbing the heat.

                                I drilled one out once and noticed that on this one board, they had these little via's or whatever you call them. You know, the copper cylindrical tubes that go through the board. I was thinking the board was multi-layered and maybe there were traces that hooked up to that via or something.

                                It's not just removing them either. When I tried resoldering a new cap in, had the same issue. Had to use hot air. Otherwise, the solder would just kinda get stuck to the via. It wouldn't melt properly and get all over the iron and not the two points that needed soldering.
                                -- Law of Expanding Memory: Applications Will Also Expand Until RAM Is Full

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                                  #56
                                  Re: How do you remove smd electrolytic caps?

                                  Yes, motherboards are multi-layered and there are power and ground planes which work pretty well as heatsinks.

                                  If the room is cold, and the board is cold, those copper areas will draw heat away from the joint even more. I found that working on boards in winter was harder. You may try to preheat the entire board and have something like a fan heater blowing warm air onto the work area to stop the board cooling down too fast.
                                  "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                                  -David VanHorn

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                                    #57
                                    Re: How do you remove smd electrolytic caps?

                                    Originally posted by Spork Schivago View Post
                                    Maybe there's some misunderstanding? I know personally, at least, I never argued the point that a micro-soldering iron would work for through-hole components. I'm not saying you couldn't use one in certain circumstances, but why would you? They're not designed for through-hole, they're designed for SMT....

                                    I was just talking about soldering in general there. I don't think anyone even makes a 120-watt micro-soldering iron, do they? I've always seen them around 40-watt or somewhere in that area....

                                    I was saying with my non-micro-soldering 120-watt Weller iron, I cannot physically melt the solder with certain through-hole components and I think with those types of components, hot air and a preheater is necessary.

                                    I don't think anyone was arguing with you about the micro-soldering irons and through-hole components, unless I missed something somewheres. You made a valid point and it just made me think about the non-micro-soldering irons and how some components just don't seem removable. Sorry if I offended you or something, that wasn't my goal.
                                    AFAIK at least 100W ones are on the market. But I still see something about pre-heating and whatever so I presume this still continues. Well, my gun handles pretty much any board in any temperature these days so all this preheating just makes me laugh and think about how much faster I can process a board than these guys. And still from financial point of view it makes no sense to recap most boards. So I wonder what's the hour tax of these preheaters, 2 bucks?
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                                      #58
                                      Re: How do you remove smd electrolytic caps?

                                      I found the cleanest way to desolder is with a vacuum desoldering gun. Sometimes I have to use hot air at the same time on tough boards. It doesn't make much time difference though.

                                      I tried high-power irons in the past but only ended up overheating things and having problems with burnt flux, oxidisation etc.

                                      How do you do it, with a 150 watt soldering gun - I assume you are talking about those?
                                      "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                                      -David VanHorn

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                                        #59
                                        Re: How do you remove smd electrolytic caps?

                                        Got 125W transformer gun, this one http://nuba.cz/produkt/pajecka-etp-5/ though it seems they recently changed the body shape.

                                        It's just about the practice. It is neccessary to use flux, more is better than less, as it helps dissipating the heat. Instead of burning the board, you burn the flux I use ordinary resin lately. Also cleaning the tip from time to time and adding fresh solder is important, when it oxidizes (resin helps against that too, however), the conductivity gets much worse, to the point the sodler joint does not even want to melt, while there is heat enough to burn the board. So having nice shiny layer of solder on the tip all the time is the best thing.

                                        Sometimes you can still melt the plastic, espcially if you don't use enough resin. I learned to prevent that by positioning the tip from a side where are no traces so when that happens, you won't damage them; the underlaying layers are so deep I've never got through to them. Usually when you look to the trace pattern, there is always some small place at least from one side around caps (while as much as three sides could still have traces running very close).

                                        This is however problem mostly just for caps around slots where there are no large copper areas so you can get reverse problem - it can overheat easily. That can be completely avoided by using smaller gun/pen for these caps (like 75 W) which is more than enough to remove these. But with some practice I can work with all of them fine, which saves the effort of constantly using different guns or pens.

                                        I however do use pen for sensitive boards with very thin layers without, especially to desolder the caps. Resoldering new caps is another matter, for that I mostly still pick the gun in the end as the pen is not able to heat the copper tube (what's the correct term for it?) through so the solder melts on the other side of the board (as it was before).
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                                          #60
                                          Re: How do you remove smd electrolytic caps?

                                          Originally posted by Behemot View Post
                                          AFAIK at least 100W ones are on the market. But I still see something about pre-heating and whatever so I presume this still continues. Well, my gun handles pretty much any board in any temperature these days so all this preheating just makes me laugh and think about how much faster I can process a board than these guys. And still from financial point of view it makes no sense to recap most boards. So I wonder what's the hour tax of these preheaters, 2 bucks?
                                          Holy cow! 100-watt micro-soldering irons??? That's insane! I can't honestly see why anyone would need such a high wattage micro-soldering iron.

                                          For me, I replace caps on a regular basis. Last motherboard I did, it would have costed around 275$ to buy a used replacement board, but the caps were maybe 50 cents each? It took maybe 15 minutes to heat up with hot air and the bad caps were in the VRM circuit. The 120-watt normal iron (not the micro) for my Weller WX2 couldn't do it. The board was just absorbing all the heat. Not sure how much it costed me in electricity to run the preheater and the hot air (I use a Weller WHP3000 pre-heater with a Weller WHA900 hot air rework station).

                                          The last full recap I did on a computer motherboard costed around 30$ for the caps, but I did one of them polymods. Not sure how much a replacement board would have costed, but it was a cheaper system. I think if the person went for the same board again, it'd have the same issue again in the future. It had wet electrolytics that actually looked like polymers. The VRM circuit (always seems to be the VRM!) had swollen caps. I think from the excess heat. That one was just a bad design. The caps were directly under the heatsink and there wasn't very much room. The polymers were much shorter and rated for an insane time before failure (something like 10,000 hours, if not more!) at 105c (or maybe higher). He's still using the PC. I recapped that maybe a year or more ago.

                                          I think now-a-days, for PCs at least, we're seeing more and more that come with those polymers and I think because they're dry, they tend to last a lot longer and we see less and less recaps for them. Do you guys agree?
                                          -- Law of Expanding Memory: Applications Will Also Expand Until RAM Is Full

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