What is the best way to test capacitors?

[Azhar]

What is the best way to test electrolytic capacitors? by using an ESR Capacitor tester or by reading the value with a capacitor meter ??
I'm trying to repair an old tv, I replaced bulged capacitors but it didn't help, I'm not sure what is the best way to test the capacitors!
should I buy an ESR meter?

[mariush]

An ESR meter would provide a more accurate information regarding the quality of a capacitor compared to a capacitance meter.  A capacitor can go bad and still report a reasonable capacitance or the capacitor will be bad when used in some situation which is not the same as the one the capacitance meter tests on (different frequency for example).

[Paul Price]

You don't need an ESR meter to check electrolytic capacitors, just an AC function on a digital voltmeter/scope, and if you have a any suspicion that an electrolytic cap is bad by a high level of AC across it, your best troubleshooting strategy would be to use alligator clips (or just temporarily solder) a known good one across the suspect bad cap to see if it removes the AC voltage drop across it or else see the circuit starts working properly. Always match the polarity marks and attach the test capacitor with power off.

The tell-tale sign that an electrolytic cap is bad is the flat top of the cap becomes dome-shaped or you can see leaking electrolytic fluid from the base. Most usually, a cap is a good cap if it isn't open circuited and the dome is flat, and you can further test it for a large AC voltage across it. If there is, the capacitor may be open or have a large ESR, so bridge a new one across it to see if this fixes the problem. Visual inspection, bridging a new cap and a multimeter AC test/scope reading best tells you that a electrolytic cap may be bad in a power supply or other circuitry, and this is a smart, time-saving and convenient to troubleshoot and make repairs because you can quickly check a capacitor even without unsoldering it from a circuit.

I've repaired electronic equipment for tens of years and the idea is get the job done quick, proper and  to make money, not wast time, effort and money on equipment you will don't need.

I haven't ever purchased either a capacitance meter or an ESR meter to accomplish my repair work.

Having spent the money that would be wasted on an ESR meter and a capacitance meter, I instead invested in buying capacitor assortments for substitution, equipment repair and also for my experimental designs.

An ESR meter or capacitance meter may sometimes tell you a capacitor is bad, but bridging a suspect capacitor with a  known good one fixes the problem, and all it is necessary to complete the repair is to then replace the defective part with a new one, which is already on hand.

BTW, I built my own capacitance meter using a PIC chip that automatically reads capacitor values by using the test capacitor as an osicillator frequency determining component, and the so period of oscillation measured then yields the capacitance value. I have sometimes come across capacitors with unreadable, unusual markings or myterious color codes and that is why I've bothered to make this cap meter one of my DIY PIC projects.

[Yago]

Good points!
Thanks for posting Paul!

[Kjelt]

The LED display based ESR meter that Dave showed in his ESR video is still being made by some persons and not that expensive ( less then €80 ). I bought one from a spanish or portugeses person who sells them and it was pretty good ( compared it with a HP meter costing four figures at work) and it was within a few percent.

I am not arguing with the excellent practice points of Paul, still for that price I find it very comforting measuring electrolytes in my (old) stock before putting them in my projects. And esp. The large expensive electrolytes that can have long lifetimes it is nice to know if you need to buy a new one to replace them or that they are still pretty good.

[Vito_R]

An ESR meter has been proven over the decades to be the most efficient, reliable, and accurate way to test capacitors.  If you just rely on a multimeter's AC voltage setting, or just using a capacitance meter, you will miss out on many caps. That method may still work to detect issues in power supply circuits but you will not always be able to effectively detect them in others.  Over 20 years in electronics servicing I have run into numerous bad caps that were testing full capacitance and not showing signs of ac ripple or any signs of bulging, leaking, or venting, until I sniffed them out with a good ESR meter.  Once replaced they solved the customer's original complaint.  Those tough dog problems were often solved by finding that high esr cap causing all the headaches.  Tantalum caps are also a problem.  Nothing can beat a good ESR meter.   Another benefit is you can often test them in circuit.  I'm completely satisfied with my Peak Atlas ESR70 which also tests capacitance, and the bob parker blue ESR meter.  Another good one I use is the EDS-88A Capanalyser II which also (at the same time) it tests esr it tests a capacitor's DCR (direct current resistance).   Investing money in good test equipment such as a good ESR meter is never a waste as it will save you valuable time and catch those hard to find cap related issues.  It can also help you ensure quality control of your replacement parts and sometimes help to sniff out those counterfeits that read high ESR.  So to answer the Ops question what is the best method to test Capacitors?, in my strong opinion, and from experience, a good ESR meter is.

[Vito_R]

If there is, the capacitor may be open or have a large ESR, so bridge a new one across it to see if this fixes the problem. Visual inspection, bridging a new cap and a multimeter AC test/scope reading best tells you that a electrolytic cap may be bad in a power supply or other circuitry, and this is a smart, time-saving and convenient to troubleshoot and make repairs because you can quickly check a capacitor even without unsoldering it from a circuit.

I can't understand or agree with that statement because what happens if you have multiple failed caps which don't show any signs of venting?  It is a lot more efficient and time saving to simply use an esr meter in circuit then to try and find an equivalent cap in your inventory to bridge across each one.  You can not always bridge them in all situations and having an esr meter next to you is a lot faster then finding and soldering on a cap. The repair would still not be complete because I would never want to leave bad caps in there to leak or leave the new ones soldered to the backside of the board like that.

[Paul Price]

Kjelt:  It might seem like you might mistrust your spare electrolytics quality if they've been sitting around your shop for 40 years or more, but it's been my experience that capacitors retain their quality if not used. High temperatures, high ripple currents and temperature cycling will cause failure.

Tell me, how often have you found an unused capacitor show fault from too much vacation time, except for those caps already in-circuit in pre-1960's electronic equipment?

Most of the arguments that taut ESR and cap meters over substitution/bridigng seem to be dealing with rare edge effects, the 1 in 10000 troubleshoot/servicing problem that no doubt occurs, but scream infrequent on the bell curve of repair experience, and that is why my technique serves best for the most often and gets the repair job done quickly.

[Paul Price]

Vitro_R says,"If you just rely on a multimeter's AC voltage setting, or just using a capacitance meter, you will miss out on many caps."

I say don't rely on  the "just rely" that forgets the substitution step. Rather than grab an ESR meter or Cap meter, as you say, just grab a new cap and quickly find that substitution/bridging is the easiest way to troubleshoot any suspected capacitor.

Substitution/bridging of a suspected capacitor eliminates the often time-consuming/clumsy steps to make use of an ESR or cap meter to only perhaps find the problem and does not repair the circuit, it deprives you of the immediate opportunity to discover that the equipment has just been fixed by substitution/bridging.

There is no question that if trying a good capacitor fixes the problem, the problem is fixed.

[Paul Price]

Vito-R says, " You can not always bridge them in all situations and having an esr meter next to you is a lot faster then finding and soldering on a cap."

Really?  If you can somehow fit the probes of an ESR meter into a circuit, you just as easily bridge/substitute a capacitor. Bridging  (or, if necessary substituting) the capacitor reveals the circuit is working and you've accomplished repair by then replacing the bad cap.

[Paul Price]

Vito_R says, "I have run into numerous bad caps that were testing full capacitance and not showing signs of ac ripple."

Really, you are saying a capacitor is working as it should but it really not working..is this some new quantum capacitor effect you've discovered using an ESR meter?

[Paul Price]

Vitro_R says,"The repair would still not be complete because I would never want to leave bad caps in there to leak or leave the new ones soldered to the backside of the board like that."

I would never leave bad caps in there either. I said bridge to check a capacitor, and of course, replace the bad cap to repair.

[Paul Price]

Vito_R says,"Another good one I use is the EDS-88A Capanalyser II which also tests a capacitor's DCR (direct current resistance)"

Really, I can test a capacitor's DCR just using the resistance function by just using my DVM/multimeter/ohmmeter function.

[Vito_R]

All I can say is    wow unbelievable 

[Azhar]

What I understood is that an ESR meter is the best way, right? any cheap models out there in ebay?

[Vito_R]

What I understood is that an ESR meter is the best way, right? any cheap models out there in ebay?

Yes an ESR meter IS definitely the best way to go.  The ones I listed above, the Peak ATLAS ESR70 and the Bob Parker Blue are excellent meters and affordable too.  I believe the bob parker blue esr meter is even available in kit form for slightly less. They also sell directly from the manufacturer and on ebay from the same guy.  I recall I bought mine fully assembled for around $100.  Less then that yes you can probably find some cheap stuff from sellers in china but I have no idea if they are any good nor would I waste my time trying to find out.  I would guess those meters might themselves have fake chinese caps in them that would eventually go bad too.  Then you would need an esr meter to fix your esr meter. 

[Vito_R]

Here is the link for the kit version of the bob parker meter.  You might enjoy assembling it yourself and learn something too.

http://www.ebay.com/itm/Anatek-Blue-ESR-Meter-Full-Kit-for-Self-Assembly-BESR-kit-/181463391631?pt=LH_DefaultDomain_0&hash=item2a400f9d8f

BTW Dave also talked about this meter in one of his videos I believe when he was trying to fix those LCD monitors with bad caps in it.  It was the old red version not the blue that he had.

here's the video:

[madires]

Kjelt:  It might seem like you might mistrust your spare electrolytics quality if they've been sitting around your shop for 40 years or more, but it's been my experience that capacitors retain their quality if not used. High temperatures, high ripple currents and temperature cycling will cause failure.

Tell me, how often have you found an unused capacitor show fault from too much vacation time, except for those caps already in-circuit in pre-1960's electronic equipment?

I also got a nice stock of electrotytic caps, oldest ones about 30 years old, and I've encountered only a few bad caps. The capacity decreases sometimes a few percent but the cap is still ok. Regarding the voltage rating I always go for a 30-50% security margin and had no issues so far. Stuff I've built using 10+ years old caps is running fine 24x7. Anyway, a nice LCR meter also measuring ESR is quite handy to check old caps. Or check out the famous Transistortester (see https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/ ).

[Azhar]

Here is the link for the kit version of the bob parker meter.  You might enjoy assembling it yourself and learn something too.
BTW Dave also talked about this meter in one of his videos I believe when he was trying to fix those LCD monitors with bad caps in it.  It was the old red version not the blue that he had.

Thanks a lot

[Vito_R]

Dave talks all about the advantages of an ESR meter in this Video starting at 5:25



He really goes in-depth and tests a whole bunch of caps with it.  Great video !

[Paul Price]

Azhur,

I would say that substitution/bridging is the best way, read my comments above.

Others here insist that you buy an ESR meter.

My long-term rexperience has taught me that bridging/substitution would be the best way to quick find problems due to defective caps and quickly repair equipment without purchasing unnecessary equipment you would likely rarely use in the future..

[wraper]

Azhur,

I would say that substitution/bridging is the best way, read my comments above.

Others here insist that you buy an ESR meter.

My long-term rexperience has taugh me that bridging/substitution would be the best way to quick find problems due to defective caps and quickly repair equipment without purchasing unnecessary equipment you would likely rarely use in the future..

It is a completely crap way. 1. it is much faster to use ESR meter. 2. you cannot check that capacitor is good, only if it is bad. You can kinda fix the device, yet there can be tons of dead capacitors left. 3. if there are multiple capacitors dead, soldering one capacitor in parallel at the time might not fix a device at all. 4. You cannot check at all how much life left in capacitors as quiet often while they are still working, many capacitors of the same type have 3-4 times different ESR what means some of them will die very soon.

[Paul Price]

Azhur,

My opinion on the best way is not just my own. I am sure if you contacted a professional business in  your area that fixes electronic equipment like TVs and Radios etc, they would tell you that they don't even own or use an ESR meter.

I have visited many repair shops and know that from discussing repair methods, my peers have also known that a substitution/bridging method is the most  common and effective practice.

I would recommend to you that you call a repair shop or two before you waste money on equipment you do not need for quick and effective repair.

[Azhar]

Azhur,

I would say that substitution/bridging is the best way, read my comments above.

Others here insist that you buy an ESR meter.

My long-term rexperience has taugh me that bridging/substitution would be the best way to quick find problems due to defective caps and quickly repair equipment without purchasing unnecessary equipment you would likely rarely use in the future..

Thanks Paul, that is how I do it usually, but unfortunately it doesn't work always with me, probably because I use second hand caps that I harvested from other old electronics, I don't think that I can buy all caps values!!

[janengelbrecht]

A good incircuit ESR meter can be found on ebay for about 37 dollar: http://www.ebay.com/itm/Digital-ESR-Meter-Test-In-Circuit-Electrolyte-Capacitor-Resistance-0-01-30-Ohm-/321424066464?pt=LH_DefaultDomain_0&hash=item4ad65e07a0
If i were to make repair work i would surely buy one.