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    #1

    Replace small caps?

    I have tried to find an answer to this question on the forums, but have not. I do appologize if this has been addressed elsewhere. I am preparing to recap a Gigabyte Ga-7ZXE. I got a price list for the 3 larger caps on the board and plan to purchase them here (thanks for the quick response Chris!).

    My question is: There are a number of itty bitty caps on this board with values of 100uF and 22uF. The lowest value listed here is 330uF. Is that because the little caps are not usually replaced?

    Thanks
    Tags: None
    #2
    Re: Replace small caps?

    Any cap ~can~ fail,,, but.

    1) If there is no vent then don't worry about it.
    They have no vent because they aren't prone to forming gas an bloating.
    Also those are usually for signal coupling and not power filtering so they don't see ripple. (a.k.a. don't work very hard.)

    2) Caps below 1000uF fail but less often as the uF goes down.

    But there are certain brands that are problematic even in the smaller values.
    Small lelon, chhisy, stone, and some others going bad is fairly common.

    What brands are the small ones?
    Mann-Made Global Warming.
    - We should be more concerned about the Intellectual Climate.
    -
    Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
    - Dr Seuss
    -
    You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
    -

    Comment

      #3
      Re: Replace small caps?

      make sure you replace the 330
      they will be choyo and are junk.

      Comment

        #4
        Re: Replace small caps?

        Originally posted by Kaptdeath
        The lowest value listed here is 330uF. Is that because the little caps are not usually replaced?

        Thanks
        Is it 330uF 25V?
        My SAMXON Capacitors Database HERE!!

        X-CON is a new brand for SAMXON's Polymer Capacitors.

        Comment

          #5
          Re: Replace small caps?

          My general rule is to replace any cap that has a vent, no matter the size. Necessary, possibly not. But it does provide peace of mind.
          A man convinced against his will is of the same opinion still.

          Comment

            #6
            Re: Replace small caps?

            I agree with you.
            It's not that much trouble to replace a few more caps after you have the system torn down. And if you skip them you may have to tear it all apart again a short time later. Thats too much in wasted time for me.
            Mann-Made Global Warming.
            - We should be more concerned about the Intellectual Climate.
            -
            Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
            - Dr Seuss
            -
            You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
            -

            Comment

              #7
              Re: Replace small caps?

              Big Pope,

              Yes, the 330's are 25V. I am replacing them with Samxons.

              PCBONEZ,

              The 22uf (16V) are Choyo, the 100uf (10V) are GSC.

              All,

              I found a blister pack of assorted capacitors at Radio Shack (only $4). Some of em are nichicons. Dunno if they are low ESR. It sounds like (for the most part) that the small caps are not replaced. I'll probably find soldering the caps I've got comming exciting enough. (this is my first) I've read the FAQ and guides, practiced a bit on a junk board and got a high watt, and low watt iron. (I have done a bit of soldering in the dim past.)

              I'll post my results.

              The Kapt'n

              PS I assume it is safe to say that ALL Choyo and GSC caps are BAD?

              Comment

                #8
                Re: Replace small caps?

                They are bad when used for power conditioning and combating ripple.
                They can't handle it. The ripple overheats them and they fail.

                Those 22uF and 100uF are most likely used for signal coupling which doesn't involve ripple and so they won't overheat. They should be fine there.
                I would even bother with those unless you just want to.

                (Guessing) The 330 probably has something to do with an I/O jack. (Sound, USB, PS2). They use the higher voltage to handle voltage spikes if someone slams in or yanks out a cable causing the load to change too fast. If those go it's not likely to keep the system from booting/running but you might have problems with what ever that I/O is.

                .
                Mann-Made Global Warming.
                - We should be more concerned about the Intellectual Climate.
                -
                Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                - Dr Seuss
                -
                You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                -

                Comment

                  #9
                  Re: Replace small caps?

                  mostly lower values tend not to be replaced but its your choice.
                  (as above posts say)

                  I would follow KC8's advice on the 330uf thought since you will have it stripped...bit of preventative maintenance wont hurt.

                  It is "critical" you use low ESR caps for the VRM
                  (caps you find around the CPU and mosfets)

                  Although "depending", quality more General Purpose series can be used for less critical area's
                  but low ESR shouldn't hurt if you have them.
                  Key here is "'quality" caps replacing rubbish with rubbish, well there's not much point really.

                  there are a scattering of posts around here on that PCB and I have one I recapped a while back still humming along.

                  here's a post by will and mine dont look much prettier but works fine
                  (and thats what counts)
                  The rub is getting the previous size diameter used, although 12.5mm is better anyway..seems to be the consensus of opinion
                  (this can be more the issue,size of can with some pcb's)
                  (I think samxon's range do have the values in the smaller diameter?)

                  https://www.badcaps.net/forum/showthread.php?t=377

                  There are extra positions that can be populated, some say do.. some say don't but it does allow you to use 2 caps of a lower capacitance if you choose to stay close to original "total capacitance" because you cant get what you need
                  (voltage must stay the same or little higher thought)

                  I did this with this box here
                  (it didn't need the caps changed but since a new CPU was being fitted)

                  https://www.badcaps.net/forum/showthread.php?t=3828

                  HTH

                  Cheers
                  Last edited by starfury1; 12-30-2007, 06:56 PM.
                  You step into the Road, and if you don't keep your feet, there is no knowing where you may be swept off to." Bilbo Baggins ...

                  Comment

                    #10
                    Re: Replace small caps?

                    I failed. I struggled. Replaced 6 caps. Decided to see if I still had a functional MoBo. I don't. I couln't really figure out how to get solder to flow through the little hole to make contact on the topside connectons. To be honest I couldn't get solder to stick to the bottom side either. Sigh. I guess it was just a little out of my reach.

                    Kapt'n

                    Comment

                      #11
                      Re: Replace small caps?

                      What kind of iron? - How many watts?
                      Need a hot one (40 watts plus) for motherboards 'cause they are thick.

                      If the solder diameter is too big that will make it harder.
                      (As in the diameter of the wire.)

                      You need to tin the solder tip.
                      Clean it.
                      Heat it.
                      Then coat it with solder.
                      [This helps heat transfer to the joint.]

                      If there is resin on the board it needs to be cleaned off for a new jont.

                      Most of all go find a junk PCB out of something to practice on.
                      Doesn't matter out of what, old TV, radio, printer, wife's hair dyer, (Oops! Leave that one alone. Trust me on this.)

                      .
                      Mann-Made Global Warming.
                      - We should be more concerned about the Intellectual Climate.
                      -
                      Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                      - Dr Seuss
                      -
                      You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                      -

                      Comment

                        #12
                        Re: Replace small caps?

                        I have a 2 40 watt irons. One with a blade tip, one with a pointy tip. I practiced desoldering on a junk board. I'm not sure what I'm doing wrong when I try to resolder the caps. The solder seems to flow up hill. I have tinned both tips and use a bit of solder to help the heat flow. Do you know of any pics showing proper technique?

                        Kapt'n

                        Comment

                          #13
                          Re: Replace small caps?

                          I've gone over every connection again. Cleaned and resoldered. The board "starts". The fans turn and the CPU and memory get warm. I hooked up the speaker. No beep at all. After about 30 seconds it starts clicking at I guess what would be about 60Hz (sounds like a cheesy toy motor sound). I'm not really sure where I have gone wrong. The keyboard lights blink but laser mouse never lights up (USB ports don't seem to have any power either).

                          Kapt'n

                          Comment

                            #14
                            Re: Replace small caps?

                            Oh, I almost forgot. I'm using some .5mm 60/40 rosin solder "for PC work" I picked up from Radio Shack. The rosin does not come off easily. I read that alchohol is usually used to remove rosin.

                            Comment

                              #15
                              Re: Replace small caps?

                              yes, alcohol can be used to remove it. I use methylated spirits. Cheap and effective.

                              Comment

                                #16
                                Re: Replace small caps?

                                Yes alcohol.
                                The normal 70/71% works good. The 90/91% a little better. (Less water in it.)
                                Both are drug store items. Any place with a pharmacy should have both.

                                Is the solder the lead free type?
                                There is nothing wrong with that but it's a little harder to learn with.

                                The object is not to heat the solder with the iron.
                                You heat the joint and then melt the solder with the heat in the joint.
                                It will 'stick' that way.

                                I haven't found any good pictorials.
                                Might wanna pick up a book at the library.

                                Solder size sounds good.
                                I use either 60/40 or 62/36/2 in either .032" or .022" with rosin core.
                                0.5 mm would be .019". To error on the side of smaller is better.
                                It takes more heat to get bigger solder hot enough to melt.

                                Before you apply the solder rub off a length of it with a rough cloth or paper towel.
                                Pinch it through the cloth with your fingers pull it through 2 or 3 times.
                                This rubs the oxidation layer off the surface of the solder.
                                Wouldn't hurt to do the same to the leads on the caps.

                                .
                                Mann-Made Global Warming.
                                - We should be more concerned about the Intellectual Climate.
                                -
                                Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                                - Dr Seuss
                                -
                                You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                                -

                                Comment

                                  #17
                                  Re: Replace small caps?

                                  Does the ehtyl work better than isoproyl? (Isopropyl doesn't seem to work all that well.) Also I looked a bit closer at that solder. It's not .5mm it's .05"! (Doh) I'll see if I can't find somethig a bit smaller.

                                  I have soldered on "normal" circuit boards before. ie. traces on one side only, and significantly bigger contact pads.

                                  Thanks for the input.

                                  Kapt'n

                                  Comment

                                    #18
                                    Re: Replace small caps?

                                    yes as above make sure the tip of the iron is clean too as pcbonze said
                                    they will darken(oxide) if left so you clean before you hit the joint
                                    ideally get one of the dry cleaner type things, wet sponge will cool the tip a bit
                                    (I found this doc PDF Here but I haven't use this so I'll leave it open for comment, but lot cheaper then what they sell the items for I suppose...
                                    see near bottom of this page )
                                    or wipe on paper towel (being careful not to burn yourself)
                                    then a quick tin of the tip
                                    you should apply solder after heating the joint for a very short time with the iron and this should only take about 2~3 seconds to make a good solder joint from start to finish

                                    Yes thats something you have to watch out for too now, as lead free solder is becoming the norm there is 2 main types of solder out there but that PCB I am sure was lead based solder...newer ones that have RoHS will be the tin type only
                                    So you will have to chase some info on that, few posts around here on it
                                    normally the old sweet spot solder was 60/40 rosin core
                                    (Flux pen or liquid flux is use to have too, for reflow)

                                    here's some links I found on soldering

                                    This one has a utube video showing it being done (scroll down a bit)

                                    http://www.instructables.com/id/EA0BG5C8JWEWP873MU/

                                    http://www.aaroncake.net/electronics/solder.htm

                                    http://www.mediacollege.com/misc/solder/



                                    http://www.kpsec.freeuk.com/solder.htm

                                    I didn't read them so how accurate some info might be I don't know

                                    Anyway Hope it helps but yes a bad solder joint can keep something from booting or worse an "intermittently" bad joint.

                                    Also watch out for solder bridges or whiskers or lose balls of solder
                                    A short circuit is something you really don't want

                                    So I highly recommend a good mag glass and good lighting to inspect the pcb joints and for bridges etc before powering it up

                                    HTH

                                    cheers
                                    You step into the Road, and if you don't keep your feet, there is no knowing where you may be swept off to." Bilbo Baggins ...

                                    Comment

                                      #19
                                      Re: Replace small caps?

                                      Ahh, that is extremely helpful. I am going to clean up the current mess and "give it another go". Hopefully I didn't ruin anything. Thanks.

                                      Kapt'n

                                      Comment

                                        #20
                                        Re: Replace small caps?

                                        Well, the patient died on the operating table. I hope that I didn't fry my CPU in the process. I don't give up so easy. I will aquire another board and try again. Thanks to all for the help. My technique improved significantly during the process. (The smaller solder, what a difference that makes!)

                                        Kapt'n

                                        Comment

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