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  • Recommend a capacitance tester?

    I have used the same 9.99 multimeter for years and it has served me well for 20 years. One of the probes has just fallen apart, so I figured this is a good time to get a new multimeter. This time I want one that will test capacitance.

    On the basis that I am now 57 11/12ths old, another 20 years will probably mean this next multimeter will be my last one. So I ought to buy a reasonable one.

    What do people recommend? I see Fluke are well regarded, with a corresponding price tag. There are many makes on the web that mean nothing to me. Are there any features that I should look for (guitar amps is about it for me).

    What budget do I need for something of good quality, but not necessarily the most expensive?

    thanks in advance

    Steve

    ps

    i am a hobbiest, so don’t need to go mad!
    Last edited by Steve Blackdog; 01-11-2021, 10:32 PM.

  • #2
    OK, first this. You say "test" capacitors. But what the typical meter does is only to MEASURE the capacitance. And that rarely is the useful information. If your 0.047uf cap measures 0.052uf, it isn't "bad". What generally matters much more is the leakage of a cap, and then its ESR. Your hand meter uses only a volt or two to check a cap, but in a tube amp the caps may face 500v, they may have voltage ratings of 630v. At one or two volts, a cap may not leak at all, and yet leaks like a screen door at even just half its voltage rating. A meter will not tell you that. ESR is Equivalent Series Resistance, a measure of how easily current flows through a cap. SOme hand meters will measure ESR these days, but all testing is done at low voltage.

    Now that being said, it can be useful to measure caps, especially if you are unsure of the color code or some such. And as a feature it doesn't usually add anything to the cost.

    You can't go wrong with FLuke meters, my model 77 has been working great for me for decades. And I have had no reason to buy other meters, so I can't say about other brands. But I do know ther are a variety of good quality meter brands, and I am sure someone will comment.

    I gave my ancient Eico 950B cap tester to my friend RJ, but it served me for about 60 years. It still works over at his shop. Google it up, there is plenty information and videos about the 950B. But it actually put hundreds of volts on the tested cap - adjustable - and you could see on the eye tube the amount of leakage. I find that old tech very useful, but it doesn't fit in your hand.

    There are techniques for checking leaking in circuit, and learning those will serve you well.
    Education is what you're left with after you have forgotten what you have learned.

    Comment


    • #3
      Originally posted by Enzo View Post
      OK, first this. You say "test" capacitors. But what the typical meter does is only to MEASURE the capacitance. And that rarely is the useful information. If your 0.047uf cap measures 0.052uf, it isn't "bad". What generally matters much more is the leakage of a cap, and then its ESR. Your hand meter uses only a volt or two to check a cap, but in a tube amp the caps may face 500v, they may have voltage ratings of 630v. At one or two volts, a cap may not leak at all, and yet leaks like a screen door at even just half its voltage rating. A meter will not tell you that. ESR is Equivalent Series Resistance, a measure of how easily current flows through a cap. SOme hand meters will measure ESR these days, but all testing is done at low voltage.

      Now that being said, it can be useful to measure caps, especially if you are unsure of the color code or some such. And as a feature it doesn't usually add anything to the cost.

      You can't go wrong with FLuke meters, my model 77 has been working great for me for decades. And I have had no reason to buy other meters, so I can't say about other brands. But I do know ther are a variety of good quality meter brands, and I am sure someone will comment.

      I gave my ancient Eico 950B cap tester to my friend RJ, but it served me for about 60 years. It still works over at his shop. Google it up, there is plenty information and videos about the 950B. But it actually put hundreds of volts on the tested cap - adjustable - and you could see on the eye tube the amount of leakage. I find that old tech very useful, but it doesn't fit in your hand.

      There are techniques for checking leaking in circuit, and learning those will serve you well.
      Yet again, Enzo, your measured(!) approach is much appreciated. It looks like capacitance is nice to have, but not a special must have feature. I might save my cash for the moment and get a new probe lead. You never know I may still be using it in another 20 years. Now let’s have a look on eBay for a nice old tester with dials and needles!

      Comment


      • #4
        SOme of the old Sencore cap testers were pretty cool too. But they still command a steep price. They called them the "Z-Meter".

        On the other hand units like my old Eico are still around at reasonable cost.

        https://www.ebay.com/itm/HARD-TO-FIN...QAAOSwdONf9ewG
        Education is what you're left with after you have forgotten what you have learned.

        Comment


        • #5
          I have a Z Meter II (LC75). It's a valuable tool for me. It tests caps under voltage and can also ring test transformers. If you don't repair for a living, it's probably not worth the investment, though. If you're looking, look for the "II". The original Z Meter (LC53) does not have an ESR test.
          "Yeah, well, you know, that's just, like, your opinion, man."

          Comment


          • #6
            I "refurbished" this old HeatKit C-3 Condenser Checker.

            Found it on ebay for a reasonable price.

            It works great!

            This is in calibration mode in the pic.

            I also found the full manual online in pdf form, very handy to have the manual.

            Click image for larger version  Name:	100_2372.jpg Views:	0 Size:	794.9 KB ID:	922311
            If it ain't broke I'll fix it until it is...

            Comment


            • #7
              Z-meter tests at voltage, and I don't know when it started, but some of them included a little post. You swung the bail (handle) around front and the little post was wedged between the bail and the cap button. It held the button in to keep voltage on the cap so you could leave it and form a cap.

              It rings transformers, which is cool, but it also measures inductance. I found that helpful when I repaired crossovers. PArts Express sold inductors in even values, 2mH, 3mH, 4mH, etc. SO if I needed a 2.6mH coil, I bought a 3, and slowly wound turns off it watching the value until I got down to 2.6.

              My old Eico unit was really a bridge, so it ran compares. It had internal caps for the standards, But it also measured inductance as long as you had some inductance of known value to put on the standards posts. I had a bunch of labelled military inductors I used that way.
              Education is what you're left with after you have forgotten what you have learned.

              Comment


              • #8
                Oh that Heatjkit unit is a great one too, Eico and Heathkit made similar products all along.
                Education is what you're left with after you have forgotten what you have learned.

                Comment


                • #9
                  Originally posted by Enzo View Post
                  Z-meter tests at voltage, and I don't know when it started, but some of them included a little post. You swung the bail (handle) around front and the little post was wedged between the bail and the cap button. It held the button in to keep voltage on the cap so you could leave it and form a cap......
                  Yes, mine has that little "post" you speak of. It's also handy for doing in circuit ESR tests on caps. It will hold the button in so that you can use both hands to check multiple caps just holding the test leads on solder points.
                  "Yeah, well, you know, that's just, like, your opinion, man."

                  Comment


                  • #10
                    I have a DIY ESR tester that's served me well. For bench leakage tests I use a cheap SMPS HT power supply from China - It cost $2.70 including post and uses a laptop power supply to generate 420v DC. The voltage can be adjusted with a pot and I though I may replace this with a rotary switch and a few resistors to give different fixed test voltages and build it into a case with some test sockets to plug in a DMM. However, Most of my work is with complete amps that have a fault, so I'm measuring leakage in the circuit itself which is always the best way.

                    The only check I make with measuring values is if a cap has a house part number and no value printed on it, or if it's a very old tubular ceramic where I can't make sense of the code. There's a handy trick though to find where a break is in a cable by measuring the capacitance at either end - the ratio of capacitance values is the ratio of the distance of the break.

                    Comment


                    • #11
                      Originally posted by Mick Bailey View Post
                      I have a DIY ESR tester that's served me well. For bench leakage tests I use a cheap SMPS HT power supply from China - It cost $2.70 including post and uses a laptop power supply to generate 420v DC. The voltage can be adjusted with a pot and I though I may replace this with a rotary switch and a few resistors to give different fixed test voltages and build it into a case with some test sockets to plug in a DMM. However, Most of my work is with complete amps that have a fault, so I'm measuring leakage in the circuit itself which is always the best way.
                      So how does it work? Do you use the SMPS in conjunction with the diy ESR tester

                      Comment


                      • #12
                        I use them separately, for different reasons. The ESR meter gets a lot of use, mainly in SS amps and especially equipment with surface mount electrolytics which can be prone to high ESR. When I take the back off any Fender Hotrod series amp from the 90s onwards, I always run across the PSU caps to see if the ESR is high as this gives a good indication of condition. With those Illinois caps the ESR rises before visible signs of oozing and the amp may be working fine at that point. There are plenty of people who don't use an ESR meter, but I really like having mine to hand and It suits the way I work and it cost me nothing to build - just scrap box parts and an idle couple of hours instead of watching TV.

                        The main reason for the SMPS is just to give a higher test voltage for tube amp caps. Ideally I'd like it to go to 450v, 500v and 600v but it seems to give good results all round at 400v. I restore a lot of vintage gear and sometimes I have to install used parts if the owner is after a museum piece that still can be used. I don't want to waste time by installing a film cap that already leaks. Some brands and types are notorious for leaking even from almost new. With electrolytics though I re-stuff these where possible - never re-use 'pulls'.

                        Comment


                        • #13
                          Originally posted by Steve Blackdog View Post
                          ... a good time to get a new multimeter. This time I want one that will test capacitance.
                          The "C" function of multimeters is often unreliable. While they may give accurate capacitance with a good cap, excessive leakage or ESR can influence the C reading and give false (often too high) results.
                          I've seen cases, where the DMM reading indicated in spec capacitance, while actually capacitance was low and ESR or leakage was high.

                          A good digital LCR meter (that's what I use) doesn't have that problem and measures real capacitance, ESR, leakage resistance (at low voltage), Q-factor as well as inductance and sometimes even more parameters.
                          - Own Opinions Only -

                          Comment


                          • #14
                            Originally posted by Helmholtz View Post

                            The "C" function of multimeters is often unreliable. While they may give accurate capacitance with a good cap, excessive leakage or ESR can influence the C reading and give false (often too high) results.
                            I've seen cases, where the DMM reading indicated in spec capacitance, while actually capacitance was low and ESR or leakage was high.

                            A good digital LCR meter (that's what I use) doesn't have that problem and measures real capacitance, ESR, leakage resistance (at low voltage), Q-factor as well as inductance and sometimes even more parameters.

                            what make and model do you recommend?

                            Comment


                            • #15
                              Originally posted by Steve Blackdog View Post


                              what make and model do you recommend?
                              We discussed LCR meters here: https://music-electronics-forum.com/...ng-gear/49200-
                              - Own Opinions Only -

                              Comment

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