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  1. #1
    Bronze Lounger DrWho's Avatar
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    Replacing those "Bad Caps"

    Worldwide, power supplies and motherboards are failing due to Bad Capacitors.
    Cap's are little devices used to smooth out the DC voltages used in all home computers. Because of some bad Cap's made by one Chinese Cap Manufacturer, motherboards and power supplies are failing.
    It's next to impossible to replace the Cap's inside a Power Supply, but the ones on a motherboard Can Be replaced, by someone with the right tools and expertise.
    Twice now, I've replaced all the bad Cap's on a motherboard with total success.
    Here's my story:

    My new MSI Motherboard, (now several years old).


    Now, several years later, I have some of the 5v Cap's bulging and causing random shutdowns. So I bought replacement Capacitors from a popular internet supplier.

    I had to remove the motherboard from the case and remove the ram and CPU.
    In this picture, I've removed the first Cap and notice that the next one is Bulging.


    Only two of the Six 5v Cap's are bulging, but I'm replacing them all so I don't have to go through this again.

    Let me stop for a moment and discuss the tools I'm using for this job.
    Many tech's will use a 'Solder Sucker' to remove the solder from the caps and to clear the holes in the motherboard. But, I've found this requires applying a LOT of heat to the motherboard.....not something I really want to do.

    So, I use a low wattage soldering pencil to heat the solder on one leg of a cap at a time just so I can pull the leg out of the board. Then once the cap is out of the board, I use a tiny carbide drill bit in a Pin-Vise to slowly and carefully drill the solder out of the hole.
    * The drill I use is slightly smaller than the "Plated Through" hole in the motherboard., so it only takes out the solder and does not damage the copper plating inside the hole

    Once the hole is cleared, I use the straight end of a dentist pick to smooth out the hole. With the hole cleared of solder, it's ready for a new Cap' to be dropped into place.
    This type of capacitor is like a battery, it has a Positive lead and a Negative lead. The negative lead on the cap is marked by a stripe going all the way down the side of the Cap'. The board is also marked for the Negative lead with a white crescent painted on the board. (see the following picture)

    With all the Bad Cap's out of the board and all the holes cleared of solder, it's time to drop in the new Cap's and solder them in. The new capacitors are in the plastic bag, just like I received them from my supplier.



    With all six of the new Cap's soldered in, it's time to replace the CPU Chip, with fresh Thermal Compound, the heat-sink & fan and the RAM. Then the board can be placed back in the case and all the connections can be restored.

    I always take this time to clean the edge connectors on the RAM and all the plug-in cards. I also thoroughly cleaned the CPU Heat-sink and fan.



    This Motherboard is now back in the case and working like new again.

    That's my story.

    Cheers Mates!
    The Doctor
    Last edited by DrWho; 2011-09-18 at 15:04.
    Experience is truly the best teacher.

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  3. #2
    2 Star Lounger Diogones's Avatar
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    All right! Way to go, Doc! If you will pardon my expression, that is one mother of a motherboard! What a great way to do it yourself, save the money for a repairman, and reuse an older computer component! Very cool.
    "Violence is the last refuge of the incompetent." - Issac Asimov, from his novel "Foundation"

  4. #3
    Bronze Lounger DrWho's Avatar
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    If the mobo was just a few months old, I could just replace it with a new one, but after a few years, replacing a mobo that's no longer in production, also involves changing the CPU and sometimes even the ram.
    Besides this is my "Baby". Except for those bad cap's, she's been wonderful to me.

    There are features on this mobo that I'll never use if it lives as long as I do. It's just not replaceable.
    So fixing what was wrong was my only alternative.
    I've been doing 'Board Level' repairs for thirty years or more, so the entire process was nothing I'm not familiar with.

    My first cap replacement was on a Dell that was given to me, because it had many bulging cap's and would not stay on for more than just a few minutes. It had ten cap's on the 5v rail and most were bulging and some even leaking out the bottom.
    It was quite a process, removing all ten cap's and cleaning up the electrolyte off of the mobo.
    The operation was a total success and I wound up giving that little PC away to a needy person.

    I made my post to show other PC tech's that this actually can be done, in one day, in the average shop.
    Removing a cap, with just two leads, is a lot easier than taking out a 40 pin DIP from a C-64 mobo, which I've done more times than I really want to remember.

    I just hope all yous techie guys will enjoy this thread. I had a lot of fun putting it together.

    Cheers Mates!
    The Doctor
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  5. #4
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    Quote Originally Posted by DrWho View Post

    So, I use a low wattage soldering pencil to heat the solder on one leg of a cap at a time just so I can pull the leg out of the board. Then once the cap is out of the board, I use a tiny carbide drill bit in a Pin-Vise to slowly and carefully drill the solder out of the hole.
    * The drill I use is slightly smaller than the "Plated Through" hole in the motherboard., so it only takes out the solder and does not damage the copper plating inside the hole

    Once the hole is cleared, I use the straight end of a dentist pick to smooth out the hole. With the hole cleared of solder, it's
    Doc,
    Hello...thanks for your post... Question ...have you ever used a "Solder Wick" type of tool to remove the solder from the "Caps".. Wouldn't recommend a "Solder sucker" either ..I have use the "wick" method with success. Regards Fred
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    PlainFred

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    Super Moderator CLiNT's Avatar
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    Very informative, not to mention extremely ambitious as well.

  8. #6
    Super Moderator RetiredGeek's Avatar
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    Dr. W.

    You truly are THE DOCTOR, a true PC surgeon! With my shaky hands I wouldn't even think of attempting such a repair.
    May the Forces of good computing be with you!

    RG

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    Plutonium Lounger Medico's Avatar
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    Fred, In the aerospace industry where I worked for many years, solder wicks were used extensively, and very successfully. In these senarios, and with the individuals our company hired at times, the drill senario Wayne mentions would probably have destroyed many several thousand dollar each circuit boards, whereas the wicks worked great.

    Wayne, thanks for a very informative post. Perhaps this will give others the "nerve" to take on a similar project. Fred's wick idea may actually save you some time as well.

    RG, the difficult part, I would think, would be the drilling of the solder. Fred's suggestion should solve this problem. Even us old timers could do it.
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  10. #8
    Bronze Lounger DrWho's Avatar
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    Guys! Guys! Guys! Gimme a break!
    I ain't no virgin to this business. Of course I've used solder wick, and before it was available in the local Radio Shack store, I made my own.
    That's really old school, but again, you have to put a lot of heat on the board to clean out the holes on a Multi-Layered motherboard.
    Enough heat to melt solder has to go all the way through the board.

    Too much heat can destroy the board, so I try to stay away from that as much as possible.
    If I were working on a single layer, single sided board, I'd not hesitate for a moment to drag out the old Solder Wick. It's a tool I've used a lot in the past. It's just not the right tool for this job.

    Don't be confused by names. When I say drill bit, I don't mean an electric drill or any other kind of motor driven drill.
    I specifically said that I use a Carbide PC drill bit, in a Pin-Vise. It's a hand tool that I turn very slowly and pull out often to gently remove the solder from the plated-through hole, without damaging the plating. I developed this process myself, many years ago, when I made my own plated-through boards. It's a COLD process that does take some time and a lot of care and patience, but it produces results that no other process I've ever tried produces.

    Yes, RG, shaky hands would be a big drawback doing this. Just a tiny bit of side torque on a barbide bit and it snaps right off. I only have a very few left, from my years of doing Prototype PC Boards for CAT, and in my own board building at home. So I exercise GREAT CARE when I'm handling them. It's like working with blown glass.

    But you're not that far away. If you need a mobo re-caped, just bring it on down here and I'll do it for you. OK?
    But you may have to buy me lunch. Eh?

    Cheers Mates!
    The Doctor
    Last edited by DrWho; 2011-09-14 at 17:27.
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  11. #9
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    I would go along with you Doc on the solder wick. On a multi-layer board it could cause a nightmare of lifted tracks. However, I did hear of a trick quite a few years back when working in a prototyping 'shop: add an extra smear of flux to the wick. It already has been impregnated with some flux, but adding a wee bit more helps the solder flow and can result in lower heat transfer to the pcb. Not something I would be tempted to do myself on an important board, but perhaps worth playing with on a spare.

    Anyway, I'm interested in your carbide drill bit solution to the plated through holes. How do you go about the "feel" when it has removed all the solder, or do you look for small amounts of copper on the bit from the through plating?

  12. #10
    Super Moderator RetiredGeek's Avatar
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    Quote Originally Posted by DrWho View Post
    Guys! Guys! Guys! Gimme a break!
    I ain't no virgin to this business. Of course I've used solder wick, and before it was available in the local Radio Shack store, I made my own.
    That's really old school, but again, you have to put a lot of heat on the board to clean out the holes on a Multi-Layered motherboard.
    Enough heat to melt solder has to go all the way through the board.

    Too much heat can destroy the board, so I try to stay away from that as much as possible.
    If I were working on a single layer, single sided board, I'd not hesitate for a moment to drag out the old Solder Wick. It's a tool I've used a lot in the past. It's just not the right tool for this job.

    Don't be confused by names. When I say drill bit, I don't mean an electric drill or any other kind of motor driven drill.
    I specifically said that I use a Carbide PC drill bit, in a Pin-Vise. It's a hand tool that I turn very slowly and pull out often to gently remove the solder from the plated-through hole, without damaging the plating. I developed this process myself, many years ago, when I made my own plated-through boards. It's a COLD process that does take some time and a lot of care and patience, but it produces results that no other process I've ever tried produces.

    Yes, RG, shaky hands would be a big drawback doing this. Just a tiny bit of side torque on a barbide bit and it snaps right off. I only have a very few left, from my years of doing Prototype PC Boards for CAT, and in my own board building at home. So I exercise GREAT CARE when I'm handling them. It's like working with blown glass.
    But you're not that far away. If you need a mobo re-caped, just bring it on down here and I'll do it for you. OK?
    But you may have to buy me lunch. Eh?

    The Doctor
    Dr. W,

    I'll keep that in mind, thanks.
    May the Forces of good computing be with you!

    RG

    PowerShell & VBA Rule!

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  13. #11
    Bronze Lounger DrWho's Avatar
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    Glad to expound on my hole cleaning technique.
    The carbide PC drill I use is smaller than the actual hole and the solder is much softer than the copper plating inside the hole.
    So as I turn the bit by hand, very slowly, I can feel it cutting into the solder. After each turn I pull the bit out of the hole to remove a small cutting of solder. The bit follows the route of least resistance and of course, that's the solder.
    Finally, the bit drops all the way through the board and the hole is cleared.
    I then run a straight dental pick, flattened on two sides, through the hole to smooth it out.
    That's an old technique called 'Broaching'.
    That step could probably be eliminated, but I do it anyway, just for a finishing touch.

    On some of the older Phenolic Paper PC boards of years ago, I've used solder wick and lifted the traces right off the board.
    Thank goodness, they were single sided boards.

    Well, I have a technique that works great, so that's really all that matters to me.
    I guess each guy will have to find a technique that works best for him.

    Cheers Mates!
    Experience is truly the best teacher.

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  14. #12
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    Quote Originally Posted by DrWho View Post
    Glad to expound on my hole cleaning technique.
    The carbide PC drill I use is smaller than the actual hole and the solder is much softer than the copper plating inside the hole.
    Doc,
    Hello... What size drill do you use ( number , letter, etc.) ? As this technique sounds like something that i would keep in mind for future reference...Regards Fred
    PlainFred

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  15. #13
    Bronze Lounger DrWho's Avatar
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    Fred,
    Near as I can measure, the little carbide bit that I use for hole cleaning is about .025" to .028" at the tip, with a 1/8" shank.

    The bit is about .005" bigger than the leads on the cap's.

    Experience is truly the best teacher.

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  16. #14
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    Thanks Doc... I will file that one away for future reference ... Just checked (had a look see) at my "Caps" when swapping out and cloning one of my HD's and they are still "lookin good" ( 2007 PC ) Just one more question ... Typically, what would the cost be to change out all the "Cap's" on a motherboard.. ? (just cap's price) haven't bought any for a loooong time.. Regards Fred

    PS: I'm re-posting your links as they are of use to all who would attempt the "Cap change" Thanks for sharing your information...

    For new caps...http://www.badcaps.net

    For PC drills... http://www.goldmine-elec-products.co...?number=G15421
    Last edited by Just Plain Fred; 2011-09-18 at 15:40.
    PlainFred

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  17. #15
    Bronze Lounger DrWho's Avatar
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    Fred,
    I regret, I don't have a camera with a Close-Up lens on it, but here's the best shot I could get of my little Pin-Vise and the
    .025" PC drill bit.
    Just to the right of the bit is a capacitor lead wire. It's just a few thousandths of an inch smaller than the bit.
    I know the wire looks larger, but that's an optical illusion.



    The caps that sit on the +5vcd buss are the only ones that fail. So those are the only ones we change.
    I don't remember now just how much I paid for the six caps I just changed out. I think it was very reasonable though.
    The best way to find out, is to just go to the WebSite and price them.

    Cheers!
    The Doctor
    Experience is truly the best teacher.

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