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  1. #1
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    Smile How to exchange caps - tutorial

    A little photo guide about how I do it :-) Dedicated to Datsun 1600 - thank you, dear friend

    You will need a classic transformer soldering iron, no less that 75W. I use this oldie one for 26 years:

    The prolonging of the soldering iron tip is necessary - additional resistance stop overheating the soldering tip too much.

    Some resin is need too:


    And a little bit of tin:


    And tin suction tool:


    ...and of course replacement caps and something with bad caps. In this case I choose very simple recap of Jaton GF2MX400 card. Of course this card is phased out and you will probably not made and 3DMark world record with it, recapped or not, but for testing or normal office use it is perfect. Thanks to it's passive heatsink and small size it is preferred graphic card, where you need just one to be. I use these cards in folding and testing machines ;-)
    I do, on the top of that, use a little osciloscope 440 Scope Plus http://www.atcweb.com/tpi440.htm - http://postimg.org/image/qc1qqciol/ ;-)

    So, let's first take a look at the card itself:

    As you can see, we gonna need:
    1x 1000uF 6.3V d8 Samxon GC
    4x 470uF 6.3V d6.3 Samxon GD
    3x 10uF 25V d4 Samxon ZS

    Let's take a look at the original caps...

    ...well, it is obvious they gotta go. Asiacon is the same as Evercon and this is the same cr*p as G-Luxon... :-(((

    Step first - desolder with the soldering iron the caps:

    Every time before use the soldering iron, dip it to the resin to protect against oxidation not only the contacts, but the actual soldering iron how wire tip. Result did not look ver pretty, but caps are gone now :-D The white or shaded (or other way highlighted) holes are typically for the negative cap polarity wires. Of course you gotta stay alert for exceptions and crazy designs, witch can swap the polarity! Sometimes it is better first take a picture of the card to have proof on how it looked before... ;-)

    Now come the hardest step - suck off tin from at least one of the holes. Choose the one that is isolated from the rest of the PCB. This way you heat up most only small piece of tin and PCB and hence you should be able to suck the tin off easily.

    Result - one hole is free.

    Now take the replacement cap - take care about the polarization (on some cards, such as Gigabyte FX5200/FX5600XT, it is contrariwise!). Caps has one longer leg, that is the positive wire. If you have free the positive hole, you are good to go. Insert the longer positive wire inside and the negative adjust to be pressing exactly against the tin in the not free yet hole. Apply only light pressure. If you need more pressure, shorten the wires, but leave the positive wire longer.


    From the bottom side heat up the tin in the negative hole and after a while (depends how big area of PCB you heating up) the cap nicely slide in place. Looks this way:

    If you got free the negative hole instead, then cut the positive wire of the cap in middle, so it get shorter that the negative wire and then work it out same way.
    Caps wires should be put thru to the end. Exception from this is only when you solder smaller or bigger spaced cap into holes that did not match. In that case - depends on how much the wires are getting dilate or closer - leave at least 3mm for the bend. Pressing too much in this case is very likely to damage almost any cap!

    When you have the cap in place as it should be, then cut off the remaining wires. Leave just about 1mm from them. And then with plenty of resin again solder them.

    Now it does not look pretty at all, right? :-( Well, let's continue till we have every caps soldered first.

    Now will come the technical spirit in action. Using brush add the spirit in place where the resin is:

    And leave couple of seconds to take effect. You can see that the resin is breaking up and melting already. You can help big chunks get off by sharpened piece of hard wood - notably increasing the rate how the resin leave the PCB.
    "It is dangerous to be right in matters on which the established authorities are wrong." - Voltaire
    "I believe that all the people who stand to profit by a war and who help provoke it should be shot on the first day it starts..." - Hemingway my config - my caps

  2. #2
    Joined
    Jul 2004
    Location
    Czech republic
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    42
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    Re: How to exchange caps - tutorial

    Then first with rubber, also wetted in spirit, rub off the remains of it. Last small remaining of the resin is best to get off by brush, wetted in spirit again. The brush has to have reasonably tough strings.

    (image also show desoldered CE filters and coils replaced by pieces of wires)

    With careful clean up you can get professional looking soldering joints.


    And now you can only be delighted looking at how the new nice caps beautifully looking at the card.


    Whole look on the card with now exchanged caps.


    With such simple graphic card with minimum caps you can be done in like 10 minutes top. And with a little work you got the assurance it will not fail you for years and years. And now back with it to the computer ;-)



    PS. sometimes happens - especially with small caps, where one can heat up with big soldering wire tip both holes - that it is possible solder the cap w/o actually sucking off the tin. Sometimes this is also the only one possibility, when the tin did not want get off and you did not want to damage the PCB... In this case simply cut the legs to be same and much shorter (so you can apply more pressure), align them right to booth holes, hold and from the bottom start heating and push... ;-)
    "It is dangerous to be right in matters on which the established authorities are wrong." - Voltaire
    "I believe that all the people who stand to profit by a war and who help provoke it should be shot on the first day it starts..." - Hemingway my config - my caps

  3. #3
    Joined
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    Czech republic
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    42
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    Smile Re: How to exchange caps - tutorial

    Trick with dental pick

    The hardest part on recapping is cleaning the holes for new caps. So, there come a little trick...



    Yep, with this is the very same dental pick your dentist use to push on your teeths. You can buy it in medical supply shops, the only slight disadvantage is that the quality ones cost premium. But the vacuum tin sucking toy is not even recommended on BadCaps, because from heated PCB it easily can suck-off small traces, or by the back impact it tear them on the mobo. Sometimes it happen for me and certain low-quality mainboards (like JetWay V266B, Abit BX133 and so on) are very prone to this.

    So, at first we have holes after desoldered cap (or never soldered cap there) full of tin:




    So just attach the pick and reasonably push on it with one hand to stay in place (beware, it is very sharp, be carefull!):




    From the other side heat up the PCB with iron and soon the pick do thru the hole like hot knife thru butter and try to push it as far, as you manage with reasonably small force:




    Immidetelly after you reach the end, start wriggling with it to sides/up and down a bit, so it will not stuck to the tin or resin in the hole:




    Now the big metal chunk of this dental pick come to play - it disperse the heat perfectly, so in just a few seconds we have a free hole:




    Now let's repear that with the second hole, when we want to solder the cap inside easily (or he is on wrong place with bad access):




    Push a little and we are on the second side easily again:




    ...and now we have both holes free and perfect for soldering new cap in:




    As you can clearly see, this methos is easy, comfortable and fast. And the dental pick clean really well. Tin does not get attached on it at all and resin only very lightly. Cleaning with piece of old clothing and technical spirit is done in few seconds. The steel is very high quality, elastic a little and very hard to break. Almost impossible, I never managed it yet and I tried Comparing that to the nevereding cleaning of the vacuum tin suction tool... well, this is not comparable at all. Productivity in recapping go very much up using dental pick. Caps almost like jumping in the board

    Sometimes it happens that in the holes remain too much tin, that create knob around the holes, where capacitor will be soldered. Such knobs that are on the top of the PCB are easy to tear off by nail or cut off by scalpel.

    Soldering was made by my 75W transformator solder, using lot's of resin. Pictures are not retouched at all and I did not even clean the board before taking the pictures. Board in question is Compaq Evo D310 one (MSI 6541 v1.0), exchange 10pcs of 1000uF 6.3V G-Luxon crap caps for 13pcs 1000uF 6.3V Samxon GC caps.
    Board works well

    Some people prefer solder wick and soldering station:
    Removal of Solder Using Solder Wick - YouTube
    Also a way to go.
    "It is dangerous to be right in matters on which the established authorities are wrong." - Voltaire
    "I believe that all the people who stand to profit by a war and who help provoke it should be shot on the first day it starts..." - Hemingway my config - my caps

  4. #4
    Joined
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    Re: How to exchange caps - tutorial

    Do you have any thoughts on repairing PSUs? Is it worth it? Very neat tutorial.

  5. #5
    Joined
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    Location
    Czech republic
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    Re: How to exchange caps - tutorial

    I do it regulary, but not when they are completely failed to the point that they did not work anymore. All brands put a known bad caps there (Enermax 620W Liberty line for example) and replacing them for a good ones is the only way your mainboard and components can survive in the long run.
    For 2, 3 years it usually work, unless you push overclock too much, or the caps are REALLY inferior (like Antec 480W Neo PSU that exploded my mainboad DFI Lanparty B ...) ... Fuhjyyu caps. I quess they did not lie in the name ...

    Many PSUs are problematic, tough. Some designs are very hard to recap, the biggest problem is the d10 limit for a 16V caps in the 12V rail. I have some 2200uF Samxon GD caps for it for me, but the best normal person can get is 1800uF Nichicon HN d10 cap (digikey no: UHN1C182MPD-ND ) ...

    Saving a 620W Enermax is worth. Saving some crap design, that is wrong from the point zero is, of course, useless. It is enought to look inside (see Johny Guru PSUs tests) the PSU to see, that "someone" stolen half of the components. So no wonder the PSU killed your mobo, lol...

    Good example - the legandary Fortron 300W PSU is - surprise, surprise - full of bad caps. There is not a single cap from good brand, all the used caps are known to prematurely fail. Yet this PSU is legendary. Why?
    Because the design is good and they did not skip at ONE single coil. The PSU is packed with these coils (that make it exceptionaly hard to recap, I did not even get to it ATM and I did not even created a whole list of used caps, lol) and that is why it never failed yet and still run powering the 1600MHz Duron "thing"

    I will recap it, because it like it, but that is a challenge. The Enermax 620W Liberty recap took my only like 3 hours from start to end. No big deal. Easy to work with, except the two caps on the active PFC, they can be soldered and desoldered only with removed the main input filter cap, but that it okay. I replaced the 390uF 400V Hitachi with 470uF 400V Panny TS-ED also, so... no biggie.
    Enermax grade of PSUs = worth to recap
    Sub-par PSUs = not worth it, unless you did not do it for fun or want the PSU for some old school fun
    "It is dangerous to be right in matters on which the established authorities are wrong." - Voltaire
    "I believe that all the people who stand to profit by a war and who help provoke it should be shot on the first day it starts..." - Hemingway my config - my caps

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