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How to Recondition (Reform) Electrolytic Capacitors and Why

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    #21
    Re: How to Recondition (Reform) Electrolytic Capacitors and Why

    Sorry , A capacitor can have zero ESR value?! I have measured with a chinese ESR meter like this

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      #22
      Re: How to Recondition (Reform) Electrolytic Capacitors and Why

      Well, I finally got off my fat bottom and took a serious approach to this project.

      What I wanted to ask is about the initial POT for reducing the 24V from my laptop brick. I can't use the wall-wart with the multi-tap transformer and the voltage selection switch because it stopped working.

      The problem is that the counterfeit Bourns 1KOhm eBay pot was either garbage, or I may have broken it, and I had to throw it out.

      I'm talking about this POT:



      Is it safe to test these pots without no current limiting load on them? Because when I was testing it, it burned itself out inside. There's a swiper inside that touches a long, helically-wrapped metal wire. After it burned itself out, there was no constant resistance anymore betwwen one of the pins and the middle, only the variable resistance worked.

      edit: momaka - is there any reason why something like an LM317 wouldn't work here? That way I can use bog-standard inexpensive POTs of which I have plenty here just to regulate the 317, and the 317 will be handling the actual current and not the POT.
      Attached Files
      Last edited by mockingbird; 05-25-2016, 09:12 PM.
      "We have offered them (the Arabs) a sensible way for so many years. But no, they wanted to fight. Fine! We gave them technology, the latest, the kind even Vietnam didn't have. They had double superiority in tanks and aircraft, triple in artillery, and in air defense and anti-tank weapons they had absolute supremacy. And what? Once again they were beaten. Once again they scrammed [sic]. Once again they screamed for us to come save them. Sadat woke me up in the middle of the night twice over the phone, 'Save me!' He demanded to send Soviet troops, and immediately! No! We are not going to fight for them."

      -Leonid Brezhnev (On the Yom Kippur War)

      Comment


        #23
        Re: How to Recondition (Reform) Electrolytic Capacitors and Why

        What would be a good idea is if the design engineers allowed this to happen in their design. By shutting down the other part of a circuit and only applying the extra needed voltage to the electrolytes. I see this would save a lot of waste.

        Comment


          #24
          Re: How to Recondition (Reform) Electrolytic Capacitors and Why

          Well, I ordered this kit for about $2... A lot better than experimenting with shoddy POTs, and it can pass a whole lot more current through.



          ...not to mention much more cost-effective. Some of the circuit is unecessary, as it's going to be drawing from a DC source, but I don't think I'm going to be using their PCB, but rather I'll be integrating it on the prototype PCB.

          As I understand it, the included POT (Those are only rated for 0.08 watts) is only controlling the transistor gate, so the amount of current passing through it is irelevant.
          Attached Files
          "We have offered them (the Arabs) a sensible way for so many years. But no, they wanted to fight. Fine! We gave them technology, the latest, the kind even Vietnam didn't have. They had double superiority in tanks and aircraft, triple in artillery, and in air defense and anti-tank weapons they had absolute supremacy. And what? Once again they were beaten. Once again they scrammed [sic]. Once again they screamed for us to come save them. Sadat woke me up in the middle of the night twice over the phone, 'Save me!' He demanded to send Soviet troops, and immediately! No! We are not going to fight for them."

          -Leonid Brezhnev (On the Yom Kippur War)

          Comment


            #25
            Re: How to Recondition (Reform) Electrolytic Capacitors and Why

            Originally posted by mockingbird View Post
            Is it safe to test these pots without no current limiting load on them?
            Yes, but only if you connect it right and don't exceed its current/power handling capability.

            By connecting it right, I mean connect the power source between the pot's fixed resistance pins. A 1 KOhm pot with a 24V power source will dissipate 0.576 Watts and 0.024 mA of current.

            Originally posted by mockingbird View Post
            Because when I was testing it, it burned itself out inside. There's a swiper inside that touches a long, helically-wrapped metal wire. After it burned itself out, there was no constant resistance anymore betwwen one of the pins and the middle, only the variable resistance worked.
            Was the pot rated to handle more than 1/2 Watt. If not, that's one reason it could have burned out. Also, if you connect the power source between the pin with variable resistance and one of the fixed resistance pins, turning the pot one way will cause the resistance to decrease and thus possibly allow a lot of current to flow through it and burn out.

            Originally posted by mockingbird View Post
            edit: momaka - is there any reason why something like an LM317 wouldn't work here?
            Not at all.

            In fact, that is a brilliant idea! The only reason I didn't suggest it is I was trying to keep the circuit simple. Simply wasn't aware you could find a kit for that for such a cheap price. $2 is well worth it, considering a LM317 regulator from Digikey/Mouser is typically at least $1.

            Originally posted by mockingbird View Post
            Well, I ordered this kit for about $2... A lot better than experimenting with shoddy POTs, and it can pass a whole lot more current through.

            https://www.badcaps.net/forum/attach...1&d=1464282735

            Nice! Mind posting a link where you found this kit?

            Originally posted by mockingbird View Post
            ... but I don't think I'm going to be using their PCB, but rather I'll be integrating it on the prototype PCB.
            I'd say DO use their PCB, but only install the components you need for your circuit.

            I see 5 diodes there. 4 of them could be for a bridge rectifier (which you won't really need if powering this from a DC source), but one of them is likely for protection of the LM317 (which you should install). Not sure what the small TO-92 transistor is for or some of the other components, but I am pretty sure it is one of the application circuits in the LM317 datasheet. So overall, I'd just assemble the whole thing minus the bridge rectifier and possibly the terminals.

            Really good kit for that price, though.

            Originally posted by mockingbird View Post
            As I understand it, the included POT (Those are only rated for 0.08 watts) is only controlling the transistor gate, so the amount of current passing through it is irelevant.
            Yes, the pot is controlling the LM317 adjust pin, and the current for that is really small.
            Last edited by momaka; 05-28-2016, 11:33 AM.

            Comment


              #26
              Re: How to Recondition (Reform) Electrolytic Capacitors and Why

              Originally posted by momaka View Post
              Was the pot rated to handle more than 1/2 Watt. If not, that's one reason it could have burned out. Also, if you connect the power source between the pin with variable resistance and one of the fixed resistance pins, turning the pot one way will cause the resistance to decrease and thus possibly allow a lot of current to flow through it and burn out.
              Yes, I think this is what I did. Doh! Oh well, it was only a few bucks.
              In fact, that is a brilliant idea! The only reason I didn't suggest it is I was trying to keep the circuit simple. Simply wasn't aware you could find a kit for that for such a cheap price. $2 is well worth it, considering a LM317 regulator from Digikey/Mouser is typically at least $1.
              Thanks

              Yup, the regulators go for between 50 cents to a dollar, depending on the brand and package type. I'm aware that I'm getting a counterfeit one, but who cares, this isn't going to handle more than an amp... Nothing that some backroom Chinese semiconductor lithography couldn't handle.

              Nice! Mind posting a link where you found this kit?
              Sure. It was this one in particular:
              http://www.ebay.ca/itm/301777278859
              I'd say DO use their PCB, but only install the components you need for your circuit.
              Ok, will do. Thanks again. Can't wait to get started on these caps and start measuring their leakage current.
              "We have offered them (the Arabs) a sensible way for so many years. But no, they wanted to fight. Fine! We gave them technology, the latest, the kind even Vietnam didn't have. They had double superiority in tanks and aircraft, triple in artillery, and in air defense and anti-tank weapons they had absolute supremacy. And what? Once again they were beaten. Once again they scrammed [sic]. Once again they screamed for us to come save them. Sadat woke me up in the middle of the night twice over the phone, 'Save me!' He demanded to send Soviet troops, and immediately! No! We are not going to fight for them."

              -Leonid Brezhnev (On the Yom Kippur War)

              Comment


                #27
                Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                To avoid this, check the capacitance of the cap. If it is higher than 20% of its specified capacitance, it is likely leaky and it is time to reform it.
                If you see the capacitance much higher than the nominal one, immediately throw it out, it will pop in several hours or days of operation. Especially if its production date is between mid-2004 and 2010.

                Comment


                  #28
                  Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                  Also if you get an amp of leakage current, or hundreds of milliamps of leakage current, throw it out... make sure you design your LM317T to be current limiting, and for the most part you shouldn't need a heatsink, I'd imagine you don't want to go over 10mA or so when reforming...

                  ...If that even.

                  Comment


                    #29
                    Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                    Originally posted by eccerr0r View Post
                    Also if you get an amp of leakage current, or hundreds of milliamps of leakage current, throw it out... make sure you design your LM317T to be current limiting, and for the most part you shouldn't need a heatsink, I'd imagine you don't want to go over 10mA or so when reforming...

                    ...If that even.
                    See first page.

                    You absolutely DO need a series resistor for each capacitor. Recommended resistance is 1000 Ohms minimum, as per Panasonic datasheets. I typically use 1 - 15 KOhms, depending on the capacity (lower capacity -> higher series resistance and vice versa).

                    The 317 regulator should only be used as a constant voltage source and nothing more.

                    Originally posted by watchmaker View Post
                    If you see the capacitance much higher than the nominal one, immediately throw it out
                    Agreed. But we need to quantify that.

                    From my experiments here, as long as the cap's capacitance is NOT over 30-40% of the rated, then you can try to reform it to see if that restores or improves its specs. And if the cap's capacitance is NOT over 20%, then the cap should still be acceptable to use/reform, provided ESR and leakage current are not reading out of spec too.
                    Last edited by momaka; 06-13-2016, 11:05 PM.

                    Comment


                      #30
                      Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                      Originally posted by momaka View Post
                      See first page.

                      You absolutely DO need a series resistor for each capacitor. Recommended resistance is 1000 Ohms minimum, as per Panasonic datasheets. I typically use 1 - 15 KOhms, depending on the capacity (lower capacity -> higher series resistance and vice versa).
                      A 10V supply at 10mA (worst case, as said 10mA is already too high) = 1K ohms.

                      Just commenting that the heatsink isn't even needed on the design and you could possibly get away with a LM317L or something like that if a constant voltage is even needed ... it just needs to be close enough.

                      Comment


                        #31
                        Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                        Hi, posting a question here as it's related to the topic.
                        I built my reformer and used two nice voltage meter LCD's that I got for almost nothing on eBay.
                        The first one sits before the pot and checks the input voltage from my variable transformer, this works fine.
                        The second one measures the voltage across the caps being charged, so if I have 6v input it will slowly rise so I know when they are reformed.
                        The problem is that the input impedance is listed as just 100K, this puts a too big load on the circuit so the caps can't actually be brought to full voltage.
                        So I'm curious if anyone has seen any voltage monitors like this but with 1M or even ideally 10M input impedance like a real multimeter has?
                        Attached Files
                        "The one who says it cannot be done should never interrupt the one who is doing it."

                        Comment


                          #32
                          Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                          If its fed from the same line, of course it has high current draw. You need some which has independent power supply and only measures. I only know about digital panel voltmeters.
                          Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

                          Exclusive caps, meters and more!
                          Hardware Insights - power supply reviews and more!

                          Comment


                            #33
                            Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                            Originally posted by Per Hansson View Post
                            Hi, posting a question here as it's related to the topic.
                            I built my reformer and used two nice voltage meter LCD's that I got for almost nothing on eBay.
                            The first one sits before the pot and checks the input voltage from my variable transformer, this works fine.
                            The second one measures the voltage across the caps being charged, so if I have 6v input it will slowly rise so I know when they are reformed.
                            The problem is that the input impedance is listed as just 100K, this puts a too big load on the circuit so the caps can't actually be brought to full voltage.
                            So I'm curious if anyone has seen any voltage monitors like this but with 1M or even ideally 10M input impedance like a real multimeter has?
                            Per, what a coincidence, was just working on this this week.

                            Great idea, those digital readouts...
                            "We have offered them (the Arabs) a sensible way for so many years. But no, they wanted to fight. Fine! We gave them technology, the latest, the kind even Vietnam didn't have. They had double superiority in tanks and aircraft, triple in artillery, and in air defense and anti-tank weapons they had absolute supremacy. And what? Once again they were beaten. Once again they scrammed [sic]. Once again they screamed for us to come save them. Sadat woke me up in the middle of the night twice over the phone, 'Save me!' He demanded to send Soviet troops, and immediately! No! We are not going to fight for them."

                            -Leonid Brezhnev (On the Yom Kippur War)

                            Comment


                              #34
                              Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                              Originally posted by Behemot View Post
                              If its fed from the same line, of course it has high current draw. You need some which has independent power supply and only measures. I only know about digital panel voltmeters.
                              It's not fed from the same line, I said input impedance for a reason.
                              "The one who says it cannot be done should never interrupt the one who is doing it."

                              Comment


                                #35
                                Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                                Only full-sized than http://www.ebay.com/itm/12V-10A-RED-...wAAOSwd4tT1uDE
                                Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

                                Exclusive caps, meters and more!
                                Hardware Insights - power supply reviews and more!

                                Comment


                                  #36
                                  Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                                  Originally posted by Per Hansson View Post
                                  Hi, posting a question here as it's related to the topic.
                                  I built my reformer and used two nice voltage meter LCD's that I got for almost nothing on eBay.
                                  The first one sits before the pot and checks the input voltage from my variable transformer, this works fine.
                                  The second one measures the voltage across the caps being charged, so if I have 6v input it will slowly rise so I know when they are reformed.
                                  The problem is that the input impedance is listed as just 100K, this puts a too big load on the circuit so the caps can't actually be brought to full voltage.
                                  So I'm curious if anyone has seen any voltage monitors like this but with 1M or even ideally 10M input impedance like a real multimeter has?
                                  Per,

                                  Just curious, did you find a solution? I'm scrapping my "prototype" if you can call it that... The board I got is very poor quality and soldering is just impossible with it, and I want to incorporate plug jacks like yours.
                                  "We have offered them (the Arabs) a sensible way for so many years. But no, they wanted to fight. Fine! We gave them technology, the latest, the kind even Vietnam didn't have. They had double superiority in tanks and aircraft, triple in artillery, and in air defense and anti-tank weapons they had absolute supremacy. And what? Once again they were beaten. Once again they scrammed [sic]. Once again they screamed for us to come save them. Sadat woke me up in the middle of the night twice over the phone, 'Save me!' He demanded to send Soviet troops, and immediately! No! We are not going to fight for them."

                                  -Leonid Brezhnev (On the Yom Kippur War)

                                  Comment


                                    #37
                                    Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                                    Best Advice: Old capacitors run on hope and dreams to keep them alive, believe in your device and it will last forever! follow your heart, you can never go wrong!
                                    My Computer: AMD Ryzen 9 3900X, Asrock X370 Killer SLI/AC, 32GB G.SKILL TRIDENT Z RGB DDR4 3200, 500GB WD Black NVME and 2TB Toshiba HD,Geforce RTX 3080 FOUNDERS Edition, In-Win 303 White, EVGA SuperNova 750 G3, Windows 10 Pro

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                                      #38
                                      Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                                      Originally posted by BigTroll View Post
                                      Best Advice: Old capacitors run on hope and dreams to keep them alive, believe in your device and it will last forever! follow your heart, you can never go wrong!
                                      Don't forget, "if they're free, they're for me!"
                                      "pokemon go... to hell!"

                                      EOL it...
                                      Originally posted by shango066
                                      All style and no substance.
                                      Originally posted by smashstuff30
                                      guilty,guilty,guilty,guilty!
                                      guilty of being cheap-made!

                                      Comment


                                        #39
                                        Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                                        According to my very long experience , and my best hobby also , you cannot revive zombies . But no one can disregard the fact that many capacitors and all kind of other components didn't serve its life terms initially , due to fast and continuous upgrading we seen in last decades , so it's always worth the try , specially when you own huge amounts you don't know their status .

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                                          #40
                                          Re: How to Recondition (Reform) Electrolytic Capacitors and Why

                                          i reform to rated voltage then add 20% once they seem ok.
                                          or use the surge voltage stated on the can.
                                          look at the data sheets.some caps give the surge rating.
                                          but i can tell you i have never needed to reform a motherboard cap.and i have installed around 20,000 caps in the last 10 years.and today i installed some 16v caps that are 15 years old.in a +12 supply for a cnc.of course they are rubycons and problems are rare.
                                          cheap crap probably should be reformed if you have no choice but to use them.

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