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How to exchange caps

Discussion in 'Project Logs' started by trodas, Aug 30, 2007.

  1. trodas

    trodas

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    A little photo guide about how I do it :)

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

    Some resin is need too:
    [​IMG]

    And a little bit of tin:
    [​IMG]

    And tin suction tool:
    [​IMG]

    ...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 ;)

    So, let's first take a look at the card itself:
    [​IMG]
    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...
    [​IMG]
    ...well, it is obvious they gotta go. Asiacon is the same as Evercon and this is the same cr*p as G-Luxon... :mad:

    Step first - desolder with the soldering iron the caps:
    [​IMG]
    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.
    [​IMG]
    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.
    [​IMG]

    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:
    [​IMG]
    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.
    [​IMG]
    Now it does not look pretty at all, right? :eek: 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:
    [​IMG]
    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.

    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.
    [​IMG]
    (image also show desoldered CE filters and coils replaced by pieces of wires)

    With careful clean up you can get professional looking soldering joints.
    [​IMG]

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

    Whole look on the card with now exchanged caps.
    [​IMG]

    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... ;)
  2. imperialreign

    imperialreign New Member

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    awesome guide, man! very well written and excellent pics for examples! I've done similar work before, but never that pretty! :toast:
    trodas says thanks.
  3. infrared New Member

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    Very tidy soldering. I take my hat off to you :)
    trodas says thanks.
  4. d44ve New Member

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    Very Nice.... thanks for the write up!
    trodas says thanks.
  5. russianboy New Member

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    75 watts?

    overkill, 25 watts is fine.
    trodas says thanks.
  6. Frogger

    Frogger

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    great little read gets right to the point look forward to more
    trodas says thanks.
  7. trodas

    trodas

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    imperialreign - thanks a lot :toast: The idea was from Bluetoth from OCW site, tough, that I should provide some guide at least how I do it. Maybe someone come with better tricks? :D
    And soldering just took some practice and time. And lot's of resin and then the cleaning, lol ;) W/O it it never looks pretty at all ;)

    infrared - thank you very much. It was just a quick work, even with the photos I was done in like 15 min or so, so... Not my best, just my best documented recap :p

    d44ve - thank you - you are welcome. Hope someone learn a bit - or come with even better ideas ;)

    russianboy - I was never be able to desolder mosfets or big caps (like imput caps in PSU) with my TWO 30W solders in reasonable time, so... My friend HoNY suggest using no less that 150W soldering iron, so go figure :D
    He also suggested that when unclear, then the hole with square soldering point is always the positive hole :p

    Frogger - thank you. Well, what more? :p I need to get some caps first to recap things :D ;) I run out of caps :nutkick:
  8. trodas

    trodas

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    Trick with dental pick ;)

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

    [​IMG]

    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:

    [​IMG]


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

    [​IMG]


    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:

    [​IMG]


    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:

    [​IMG]


    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:

    [​IMG]


    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):

    [​IMG]


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

    [​IMG]


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

    [​IMG]


    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 ;) :D

    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 :)
    lemonadesoda says thanks.
  9. spearman914

    spearman914 New Member

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    WOW... This is a great guide along with nice pics. But what happens if you do anything wrong?
  10. niko084

    niko084

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    Then you may or may not have a very serious problem :)

    Nice writeup, done this myself a few times.
  11. DanTheBanjoman Señor Moderator

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    First I have to agree that 75W is overkill.

    Second, I miss an essential part of the guide. Why would one want to replace caps? The example shows no bulging caps or anything and I see no argument for performance or whatever.
  12. spearman914

    spearman914 New Member

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    That question "Why would one want to replace caps?". Um, incase its broken so you don't need to buy a new mobo.
  13. lemonadesoda

    lemonadesoda

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    Dobry!

    Very nice guide. Excellent photos! Seriously good photos. As good as any professional stock imagery. Very nice. What camera are you using? How are you lighting it? Are you on tripod?

    I disagree. Speed soldering is the way to go, once you know how to do it. Having an underpowered iron, like 25W, means that it takes too long to heat up a small area. In the time it takes to hold the iron to heat the solder to melt... there is too much conduction of heat to the component, the PCB and other components. This can cause unwanted damage or heat blistering of the lacquer on the PCB.

    I have an iron, which i recommend, that is 25W with a 140W burst button on the handle. That way you quick-heat the tip, then apply, then done.

    There is nothing worse than holding an iron on a component for a long period trying to solder/desolder. Not only does it potentially cause damage to the component, if you are doing 10x or 100x of solders, it really slows progress.

    Notice that the yellow iron that trodas is using has a trigger on it. So it is 75W controlled "burst". Such an iron is 10x better than a fixed 25W iron.
    Last edited: Jun 4, 2008
  14. DanTheBanjoman Señor Moderator

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    Amazing how people never read what I write. Why do I keep bothering... Additionally it wasn't even about a mobo.
  15. niko084

    niko084

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    He is simply saying that he should add a few things to reasons why someone would want to replace capacitors.
  16. imperialreign

    imperialreign New Member

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    I completely agree - I've only recently gotten back into soldering PCBs, and I've found even a 35/45W unit doesn't produce enough heat to liquify the solder before it starts cooking components.

    Although, I've found when working with small surface-mount components, 15W-25W is usually just enough, but I've been shying away from such low outputs when dealing with through-PCB headers.



    BTW, @trodas - excellent addition to the guide, man! I've got a set of picks in my toolbox at the shop, I don't know why I never thought to use them to clean solder out of PCB terminals! :slap: = myself
  17. trodas

    trodas

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    spearman914 -
    Thanks. Well, then depends much much wrong this is and if you discover it before powering the thing back on, or not. Usually there is not much problems. Caps are easy. Smaller SMD mounted componets with MANY legs, well, that IS the challenge.
    Of course this little photoguide was never meant for people that cannot solder well.
    If you solder something wrong, you just can clean it and solder it again and again... till you do it right. Practice on dead/worthless stuff first.



    DanTheBanjoman -
    I don't know who are you agree with, however it is clear to me you never exchanged caps on few mainboards/gfx cards or PSUs. I did, as you can see, just a few of my photo-documented recaps for witch I did not lost pictures (yet):
    http://capsmod.net/forum/viewthread.php?tid=94&extra=page=1
    http://capsmod.net/forum/viewthread.php?tid=121&extra=page=2
    http://capsmod.net/forum/viewthread.php?tid=130&extra=page=2
    http://capsmod.net/forum/viewthread.php?tid=76&extra=page=1
    http://capsmod.net/forum/viewthread.php?tid=80&extra=page=1
    http://capsmod.net/forum/viewthread.php?tid=81&extra=page=1
    http://capsmod.net/forum/viewthread.php?tid=167&extra=page=1
    http://capsmod.net/forum/viewthread.php?tid=169&extra=page=1
    http://capsmod.net/forum/viewthread.php?tid=266&extra=page=1
    http://capsmod.net/forum/viewthread.php?tid=267&extra=page=1
    http://capsmod.net/forum/viewthread.php?tid=327&extra=page=1
    http://capsmod.net/forum/viewthread.php?tid=342&extra=page=1
    http://capsmod.net/forum/viewthread.php?tid=346&extra=page=1
    http://trodas.wz.cz/index.php?act=ST&f=16&t=337&s=

    You are wellcome to try 35W iron on PSU recap, or even Vcore recap. I had problems with 75W there, so...

    Well, if you miss that, then you probably also miss this thread:
    http://forums.techpowerup.com/showthread.php?t=39327
    witch well explain why it is mandatory to replace known bad caps, as Asiacon is. People all around the world contributed to this bad caps list:
    http://capsmod.net/forum/viewthread.php?tid=19&extra=page=1
    ...so you know what cap are you facing. Any many bad caps did not show any bulging or leaking, yet they still can and in the end will fry your HW.
    There are also good performance reasons for recap to more quality caps, as I confirmed the findings of other that using quality Vcore caps end up in consistently faster SuperPI scores that on completely stable machine, but with worser a bit caps...!
    http://capsmod.net/forum/viewthread.php?tid=130&extra=page=2


    lemonadesoda - good points ;) Thanks.


    imperialreign - you see, experience if worth everything. And well, when I cannot yet recap my X-Fi, then I can do a little guide that might help someone, or might not ;)
    Some people will just reject it, so, whatever :D
    Glad you learn something usefull, but practice on dead/worthless HW first ;)

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