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    Little tiny cap desoldering / testing

    Hey everyone

    I have an ESR meter and a rework station...

    It seems as thought I get weird readings from the tiny capacitors (the one's the size of a flea poop).

    Will a standard ESR meter be able to measure those sort of capacitors? If not how do you test them?

    Also, what is the best way to desolder them?

    #2
    Re: Little tiny cap desoldering / testing

    Are you talking about those tan, small, SMD ceramic capacitors? (see picture)
    https://www.badcaps.net/forum/attach...9&d=1300064779

    If so, I just remove them with a soldering iron. Since you have a rework station, I assume it also has a regulated iron built in, along with different tips for the iron.
    - If yes, use a flat tip (if you have one) by putting a little solder on it and then touch both metal pads of the capacitor on one side. It should come off clean after 1-3 seconds of heating. Don't push on the cap too hard or you may rip the pads off on the board and cap.
    - If no, a regular iron with a conical tip should work too, but you may have to put a bit of solder on the cap as well before trying to desolder it. Desolder in same was as with flat tip above.

    As far as checking those ceramic caps with the ESR meter - it's not always the best choice. Those ceramic caps like to fail short-circuit or close (usually <10 Ohms) so an ESR meter might fool you that the cap is okay when it actually isn't. Therefore, in addition to checking those with an ESR meter, check them with a multimeter as well. If any of them read shorted with a multimeter, remove the suspect ceramic cap in question and test it out of circuit with the multimeter again - it should show open circuit.
    Last edited by momaka; 06-22-2012, 09:47 PM.

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      #3
      Re: Little tiny cap desoldering / testing

      Originally posted by momaka View Post
      Are you talking about those tan, small, SMD ceramic capacitors? (see picture)
      https://www.badcaps.net/forum/attach...9&d=1300064779

      If so, I just remove them with a soldering iron. Since you have a rework station, I assume it also has a regulated iron built in, along with different tips for the iron.
      - If yes, use a flat tip (if you have one) by putting a little solder on it and then touch both metal pads of the capacitor on one side. It should come off clean after 1-3 seconds of heating. Don't push on the cap too hard or you may rip the pads off on the board and cap.
      - If no, a regular iron with a conical tip should work too, but you may have to put a bit of solder on the cap as well before trying to desolder it. Desolder in same was as with flat tip above.

      As far as checking those ceramic caps with the ESR meter - it's not always the best choice. Those ceramic caps like to fail short-circuit or close (usually <10 Ohms) so an ESR meter might fool you that the cap is okay when it actually isn't. Therefore, in addition to checking those with an ESR meter, check them with a multimeter as well. If any of them read shorted with a multimeter, remove the suspect ceramic cap in question and test it out of circuit with the multimeter again - it should show open circuit.

      Thanks so much

      but could you elaborate on what I should be looking for with the multimeter? What should the multimeter read?

      Also, what happens if I rip the pads off the motherabord / capacitor? is there anyway to fix that?

      Comment


        #4
        Re: Little tiny cap desoldering / testing

        Originally posted by pnutbutters View Post
        but could you elaborate on what I should be looking for with the multimeter? What should the multimeter read?
        https://www.badcaps.net/forum/showpo...1&postcount=23
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          #5
          Re: Little tiny cap desoldering / testing

          [QUOTE=pnutbutters;247148]but could you elaborate on what I should be looking for with the multimeter? What should the multimeter read?[/quotes]
          If you are new to using a multimeter, see this video:
          http://www.youtube.com/watch?v=bF3OyQ3HwfU

          In the past, I've seen many people get confused with the readings on their multimeter, so let me state the following:

          1) When measuring (whether that be a voltage, a resistance, or a current), always state the units. A number by itself is meaningless without any units. For example, stating that the resistance of some component is "2.3" is completely useless, because that resistance could be 2.3 Ohms, 2.3 KOhms (2300 Ohms), or 2.3 MOhms (2300000 Ohms) - which is quite a difference!

          2) For manual multimeters, a "1" on the left side of the screen does NOT mean 1 V or 1 Ohm or 1 A. It simply means the voltage/resistance/current you're trying to measure is higher than the scale on the current setting on your multimeter. In that case, just move to the next higher scale.

          3) For auto-ranging multimeters, the word "OL" means that the voltage/resistance/current you're trying to measure is higher than what your multimeter can measure

          4) A short-circuit is a very low resistance - ideally close to 0 (zero) Ohms. When measuring resistance, touching the probes on your multimeter together will give you a short-circuit. Due to the variation in multimeters, some may read all the way down to 0 (zero) Ohms, while others may read higher such as 0.8 Ohms or even all the way up to 2.0 Ohms (it all depends on your multimeter's accuracy). So before checking a resistance, always make sure to check if your multimeter is working by touching the probes together and verifying that you get a very very low resistance.

          5) An open-circuit is a very high resistance - ideally close to infinity Ohms. An open circuit will show either a "1" on the left side of the screen or "OL", depending on whether you have manual or auto multimeter.

          Now with all that out of the way, what you want to do with ceramic capacitors is to check if they have become shorted (since this is their typical failure mode). In theory, a capacitor will have infinite resistance and should read open-circuit. However, due to other components in the circuit, a ceramic capacitor may not (and most likely won't) read open-circuit in the circuit. Do not be alarmed if this is the case and you do see a finite resistance when checking a ceramic capacitor in circuit. However, if the capacitor shows a very low resistance such as 10-20 Ohms or less, you should remove the capacitor from the circuit and measure the resistance across it. Out of circuit, it should show open-circuit on your multimeter. If it doesn't, it is bad.

          Originally posted by pnutbutters View Post
          Also, what happens if I rip the pads off the motherabord / capacitor? is there anyway to fix that?
          On the motherboard, it depends how badly you do it. Most of the time it's fixable, but it may not be very easy.
          On the capacitor - ceramic caps have pads on all 4 sides, so you can just rotate the cap to a side that still has the pads. I don't recommend this, though. Generally I replace the cap when that happens.

          *EDIT*
          lol retiredcaps, you're definitely on a roll - always making posts shortly before me . Wish I could remember all of my posts like you so I don't have to type information again over and over.
          Last edited by momaka; 06-24-2012, 12:14 AM.

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            #6
            Re: Little tiny cap desoldering / testing

            Originally posted by momaka View Post
            2) For manual multimeters, a "1" on the left side of the screen does NOT mean 1 V or 1 Ohm or 1 A. It simply means the voltage/resistance/current you're trying to measure is higher than the scale on the current setting on your multimeter. In that case, just move to the next higher scale.
            This is easily the number 1 error. Most people report "I get no reading".

            Also discussed in the section entitled Multimeter at

            https://www.badcaps.net/forum/showpo...4&postcount=19

            Wish I could remember all of my posts like you so I don't have to type information again over and over.
            My bookmark list is huge.
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            We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

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              #7
              Re: Little tiny cap desoldering / testing

              Originally posted by momaka View Post
              Wish I could remember all of my posts like you so I don't have to type information again over and over.
              Already re-using your new post in less than 24 hours here

              https://www.badcaps.net/forum/showth...t=19846&page=2
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              If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

              We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

              Please do not post inline and offsite as they slow down the loading of pages.

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                #8
                Re: Little tiny cap desoldering / testing

                Originally posted by retiredcaps View Post
                Already re-using your new post in less than 24 hours here
                https://www.badcaps.net/forum/showth...t=19846&page=2
                Lol, cool
                I guess I better start following your example. I already save pretty much everything else in favorites/bookmarks. Not sure why I haven't been doing this before.

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