how to find bad caps if they measure/look good??

[smile]

Re: how to find bad caps if they measure/look good??

Than't for you reply.

What about:

But a good 1 ufd, 200 volt aluminum electrolytic can have an ESR of 100 ohms or more. That is beyond the measurement range of all of the meters listed above!

Film capacitors make matters worse. A good 1 ufd, 200 volt metallized polypropylene capacitor can have an ESR of less than 50 milliohms. Yet it's capacitive reactance at 100 Khz is approximately 1.6 ohms, at 50 Khz it is 3.2 ohms. The result is that all of the meters evaluated here except the Atlas ESR60 will indicate 1 ohm or more for such a capacitor even though there is nothing wrong with it. The ESR60 analyzes the capacitors real and imaginary impedances eliminating the reactive component so it can measure the ESR of any capacitor.

Also do they accept paypal? by now, it is available in Russia for some time now.

[mariushm]

Re: how to find bad caps if they measure/look good??

Yes, it's possible for a 1uF 200v electrolytic to have an esr that's over 100 ohm, but it's rare. Most modern capacitors (made in the last 5-10 years) won't have such high values.

Highest I saw were 2.2uF and 4.7uF rated 400-450v, their esr was around 7-12 ohm, and this is normal.

1uF 50v electrolytics had about 4 ohm esr but pretty much anything over 22uF or so should be below 1 ohm these days.

Yes, I paid using Paypal.

[smile]

Re: how to find bad caps if they measure/look good??

The defect thread at their forum does not seem encouraging, the most worrying part is that the meter does not seem to have even similar protection as esr 70

http://www.radiodevices.ru/forum/index.php?topic=11.15

[smile]

Re: how to find bad caps if they measure/look good??

By the way it seems the Russians calibrate their ESR micro v4 with Atlas ESR 60, perhaps now with ESR 70. What a bummer, I thought that they are using at least some kind of LAB grade equipment over there.

"Все девайсы настраиваются, используя Atlas ESR60 в качестве "эталона"

"All devices are adjusted, using Atlas ESR60 as 'the standard ' "

[mariushm]

Re: how to find bad caps if they measure/look good??

Well, it's been said several times already.

All these cheaper esr meters, atlas esr60, 70, blue esr, esr micro and so on, will give you a value that's "close enough" to the real esr of the capacitor. They don't compute the "real" esr, the 100kHz test signal may not even be an exact 100 kHz signal but it doesn't matter for repairing stuff, and it's the compromises you make to get them cheap.

ALL will report an incorrect value, so it doesn't matter that meter x will give you a value 0.5% further away from the esr60/70 value, which is 5-10% away from the actual ESR.

If you want precision, it's been said several times already, you have to invest into real lcr meters with esr function, that go into hundreds of dollars.

The ESR60/70 is just a "commercial" product, made in volume, that's also cheaper than proper lcr meters with esr. So it's natural the Russians developers having easier access to them, they used it to test the calibration... not everyone can pay for 4-5 digit bench meters to calibrate a tool that's not designed to give accurate values in the first place.

As for you mentioning the failures, from the google translation of that thread, i gather that lots of people don't have an understanding of how capacitors work in circuit.

They test a capacitor on a motherboard expecting to get 1000uF but fail to understand that capacitor may be in parallel with other capacitors on the motherboard (so the capacities add up, esr decreases), or there may be a drain resistor (to empty the capacitor when system is turned off) across the capacitor leads which confuses the meter's calculations, thus giving a not so accurate value.

[smile]

Re: how to find bad caps if they measure/look good??

Yes I understand that there are more expensive meters out there. The one thing that seems questionable that Russian meter is specified as

0.02…65535uf vs. 1... 22000uf for ESR 70
ESR range 0…200 ohms. vs. 0...40.0 ohms.

So is only natural question, if range is higher then how can it be calibrated using a meter that measures only from 1uf when the russian meter from 0.02uf?

The more expensive option would be to get this meter:
http://www.reichelt.de/Induktivitaet...d7f5d70e8c9a84
I would expect the Russians to use at least this meter, for the logging tracking option. Then again why they did not steal from some Russian army base a military grade equipment is beyond me, those even were sold for few $ when soviet union fell apart. Even now you can buy precision grade pretentiousness in Russia for like 5$ when on farnell they cost 200$

But I'm not making some scientific calculations, I don't need the USB logging options either, I just want to understand what is enough to troubleshoot cap problems. When I was looking for DMM I had to get the Agilent U1252B I mentioned above because I had few projects where low current was required to be stable, I needed equipment to be able to measure that. So the average DMM that was inaccurate on the mA scale was not acceptable.

I have old Russian made analog TL-4M meter that is good too, there are some precision resistors there that if damaged would cost about 500$ to replace, so you can image my high expectations for the Russian meter.

However it's a thing of intention, if you were tough that you are responsible for the quality you make, and you can't sell anything below that level. (It's exactly what we expect when we mention "made in germany" or "made in japan") If one just wants to make money then they use made in china parts. I have some smd switches made in china too, they are very bad quality. Why use them when you will have many clients experience problems is not understandable in my head.

I mysel have a bunch of unsoldered caps, about 200 or more, so I think the meter would pay for itself if I could make sure they are good. Now I wonder why nobody sells used quality tested caps on ebay etc. Good caps for a fraction of the cost, heck I would buy those myself.

[mariushm]

Re: how to find bad caps if they measure/look good??

The difference in capacity ranges has nothing to do with precision, but rather with the way the capacitance is measured.

It might also have something to do with the microcontroller choice or better put, the esr60/70 may be limited to 22000 because it's conveniently under 32767 which is a signed two bytes variable, while esr micro can do 65535 which is an unsigned 2 byte variable.

These cheap meters measure capacitance in the way explained in this link, or in a very similar way to the way explained in the link below:

http://embedded-lab.com/blog/?p=4400
http://tutorial.cytron.com.my/2011/0...citance-meter/

Basically all use this method:

make sure capacitor is discharged
start sending power to the capacitor (and measure the voltage on the capacitor) until a certain voltage is reached, for example 0.5v
record time
start discharging capacitor through a known resistor until capacitor is discharged to a certain threshold, for example 65% of 0.5v
record the time
Now compute the time difference and knowing the resistor value the capacitor was discharged through, you can determine the capacitance.

So basically the peak voltage and the resistor choice determines how low or big of a capacitance is the meter capable of measuring. But the actual precision is determined by how often the controller checks if the voltage went down to that percent when the capacitor is drained, the discharge resistor's value (if they use 1% resistors or less, or 5%, how accurate you are when starting and stopping and for how many microseconds you do it every time, if they actually measure the resistor and store the value in an eeprom or just ignore the deviation).. and other minor things.

If a meter uses a controller running at lower frequency to save battery power for example, or because it's a cheaper controller that can only go to a maximum frequency, and measures the voltage during discharge less often, it will have less precision.

For example, let's say it tests this voltage during discharge 100 times a second... that's every 10ms. A 1 uF may be discharge in 30-50ms so that's good enough for the meter to say it's 1 uF but a 0.47 uF may discharge faster than 10 ms, so the meter can only be able to say it's under 1uF.

But if you increase the measurements to 300-500 times a second and use shorter pulses of power and maybe raise the voltage to 1-2 volts instead of 0.5v, you can go as low as 0.01 uF (sidenote: generally meters want to keep it below 0.5v, because this way they can advertise it as in-circuit because 0.4-0.5v sent through the probes is below the trigger voltage for a diode or transistor or most ICs, which means components around the capacitors are unlikely to be enabled on the board)

Most go further than this by initially measuring with a top voltage and a fixed resistor, and if the capacitance is found to be the maximum capacitance it could determine with that resistor and top voltage, the controller switches to another peak voltage and another value of resistor, or maybe a difference discharge percent.

The ESR60/70 may have 2-4 such steps, the esr micro probably has one more.

So basically, the accuracy depends strictly on processor power and how often the math is done during discharge cycles... but processor power means battery consumption and the esr60/70 battery is horrible.

ESR70 says it can measure the capacitance with a +/- 4% error ... real multimeters can do it at below 1%.

That 4% error is consistent to this measurement method and in real world, doesn't matter that much, electrolytics are +/- 20% from the start so who cares.

Looking at the ESR70 internal pictures, I don't see an oscillator on the board, so they probably use the internal oscillator of the microcontroller or a RC combo to give the microcontroller the frequency.

Internal oscillators can deviate quite a bit from actual frequency, depending on microcontroller manufacturer (arduino internal oscillators are notorious for being lousy), and if the frequency isn't really the one you think it is, then the instructions will take more or less time, delays in your code are wrong, and the precision will decrease.

[smile]

Re: how to find bad caps if they measure/look good??

So could you comment on the meter I mentioned earlier:

Seems to be better deal even if overkill cause I do not need LCR or the orther functions, but PEAK LCR is 99Eur + 119Eur for ERS = 218 so its more expensive if you put it that way.

http://www.reichelt.de/Inductance-an...d7f5d70e8c9a84

I agree the batteries are bad, and not cheap. The screen is very small cause batteries drains it, but it's also hard to read because digits are very small.

[mariushm]

Re: how to find bad caps if they measure/look good??

That Peaktek looks good, it sounds like it's a proper LCR meter with ESR and connectivity to pc through USB.
It even has what seems to be kelvin clips which are better than regular probes if you want precise measurements.

There's some pictures of it and some discussion, apparently it's a rebranded Yihua V&A VA520B: http://www.eevblog.com/forum/reviews...2170-teardown/

The processor used is a Cyrustech pair of chips which are the same chips used by other meters, including that Mastech I talked about, which is $185 on eBay, $170 if you order it directly from the guy outside eBay (he's on eevforum.com and lots of people bought from him)

ebay page: http://www.ebay.com/itm/Mastech-MS53...item27cf742c84

his eevblog thread with discount: http://www.eevblog.com/forum/buysell...mber-discount/

the meter discussion page: http://www.eevblog.com/forum/testgea...at-the-moment/

review 1 : http://www.youtube.com/watch?v=9el9mW5woSM

Basically, it's about 100$ cheaper than this Peak.

BUT we're going back to the beginning... what exactly are you looking for ?!!! Some simple tool to determine if a capacitor is bad or not, or some semi-professional tool you'll use a lot? And... IT'S STILL 170-200$ !!!

If you need something just to check if a capacitor is bad or good when you're repairing stuff, you can do fine with a $50-60 esr micro , or even a $79 Blue ESR (+shipping) that you will assemble yourself : http://www.anatekcorp.com/blueesr.htm

It's a good idea (and it's very simple to accept it) to upgrade to this lcr meter or a Mastech instead of Peak ESR because the price difference is small, but the reality is the Peak ESR is seriously overpriced compared to other options you have in the same performance range.

It's not worth more than 100$... even 100$ is too much, and I see it's actually around $133.

If you just plan to fix some stuff, not be a repair technician and do this for a living, I just don't see why I'd pay $100+ for ESR70 or $200-250 for lcr meter when you can pay 50-80$ for esr micro or blue esr and use the difference for a good soldering station or whatever else you may use in the future.

[capkid]

Re: how to find bad caps if they measure/look good??

I've been using the ESR Micro V4 for a couple years, and I like it. I was repairing a Polaroid TV that had no bulging caps (HEC capacitors), and the ESR Micro helped me identify ten high ESR caps. After replacing the caps, the TV worked great.

[smile]

Re: how to find bad caps if they measure/look good??

That Peaktek looks good, it sounds like it's a proper LCR meter with ESR and connectivity to pc through USB.
It even has what seems to be kelvin clips which are better than regular probes if you want precise measurements.

There's some pictures of it and some discussion, apparently it's a rebranded Yihua V&A VA520B: http://www.eevblog.com/forum/reviews...2170-teardown/

The processor used is a Cyrustech pair of chips which are the same chips used by other meters, including that Mastech I talked about, which is $185 on eBay, $170 if you order it directly from the guy outside eBay (he's on eevforum.com and lots of people bought from him)

I can get the MS5308 for 160$ locally in the shop, but since I don't personally like Mastech or UNI-T harware (I would take it if you donate it but not buy one). I tried to get their top of the line multimeter "MS8050 53000 COUNTS AUTORANGING BENCH TOP MULTIMETER" the problem was very bad reputation on russian forums (one guy replaced 5 of them in a row, bad solder job like all of their instruments, flux not cleaned, and usual there is are some wires soldered somewhere they should not be like in your review), and I myself has to replace it twice in a 3 month period. I got my money back and got Agilent U1252B afterwards, sure agilent was more expensive but works for over 2 years, and comes with rechargeable 9v battery, so it was zero investment after I got it.

BUT we're going back to the beginning... what exactly are you looking for ?!!! Some simple tool to determine if a capacitor is bad or not, or some semi-professional tool you'll use a lot? And... IT'S STILL 170-200$ !!!

Looking for simple tool (preferably not built in china and no ROHS nonsense)
The ERS 70 plus seems the only one that can discharge caps so far, russian meter is not ready, but it seems they are going to update it to be able to discharge caps too.

If you need something just to check if a capacitor is bad or good when you're repairing stuff, you can do fine with a $50-60 esr micro , or even a $79 Blue ESR (+shipping) that you will assemble yourself : http://www.anatekcorp.com/blueesr.htm

For the money they could have included 4 digit display, it seems too basic even for me.

It's a good idea (and it's very simple to accept it) to upgrade to this lcr meter or a Mastech instead of Peak ESR because the price difference is small, but the reality is the Peak ESR is seriously overpriced compared to other options you have in the same performance range.

Sure, but if it's soldered better and I don't have to clean flux from my new meter in ultrasonic bath that makes it even.

If you just plan to fix some stuff, not be a repair technician and do this for a living, I just don't see why I'd pay $100+ for ESR70 or $200-250 for lcr meter when you can pay 50-80$ for esr micro or blue esr and use the difference for a good soldering station or whatever else you may use in the future.

The ESR Mciro is nice, the resolution is better, it can measure tantalum (mall caps etc.) but the stability is questionable. I would like to buy a meter with 0.1% resistors, capacitors etc. They are expensive if you buy them by one from sites like farnell, elfa.se, etc. but for assembly when you buy reels you save 70% cost. So when you say all accuracy is is those basic components you are correct there is also factor of temperature drift ppm/C.

I wonder what components ESR70 used compared to ESR micro 4? Is there a comparison somewhere? Is there review of these two meters side by side? Where the reviewer is intelligent enough to measure same caps 3, 4 times so make sure the result is stable? All I see are kids playing with their new toys on youtube.

[smile]

Re: how to find bad caps if they measure/look good??

Mastech 5308 defect:
http://radiodvor.ru/novosti/pribory/Mastech-5308-defect

Defect in ESR-micro v4.0, made from 16.12.2010 to 15.01.2011
http://www.istpit.ru/showthread.php?p=281

[mariushm]

Re: how to find bad caps if they measure/look good??

I can get the MS5308 for 160$ locally in the shop, but since I don't personally like Mastech or UNI-T harware (I would take it if you donate it but not buy one).

I tried to get their top of the line multimeter "MS8050 53000 COUNTS AUTORANGING BENCH TOP MULTIMETER" the problem was very bad reputation on russian forums [...]

That happens with other meters as well. Uni-T has meters that are designed by various engineering teams, some are awful, with glass fuses, with traces going through places they shouldn't go and all that, while other meters are excellent for the money and designed nicely. For example, I have a Uni-T UT61E that looks great inside.

Without opening it up personally or checking some high res pictures or seeing review, I couldn't tell you if a Uni-T meter is worth buying, and the same thing I would say with other meters if they're not Fluke, Agilent, Brymen and maybe a couple more brands.
There's brands considered very good that also produce crap meters, or rebrand meters from other companies and make more profit by taking out protection parts, replacing fuses with cheaper fuses... Extech comes to mind, Amprobe as well.

The point is there's a huge difference in the costs of the tool from a brand name like Fluike and one from Uni-T and Uni-T and depending on what you want to do, it may be worth getting the cheaper multimeter

As for Peaktech lcr meter, like I said, it's a Yihua V&A VA520B rebrand.

Yihua in my mind is the manufacturer of soldering station clones, such as Yihua 936 which is a Hakko 936 clone - they're even copying the case design and everything: https://www.google.com/search?q=yihu...I4LQtQaM0YGICA

So what guarantee do you have that they'll make that meter an original design, or that it's made properly? It's probably the reference design of the chipset used.

You can't be sure it's a good tool without seeing internal pictures first, reviewing it etc and luckily that Mastech MS5308 was reviewed by at least two persons before... you have the Youtube video and you have the Eevblog discussion thread with pictures of the insides.
You can make a determination from that if it has soldering issues, if there's flux left on the boards and all that.

Looking for simple tool (preferably not built in china and no ROHS nonsense)
The ERS 70 plus seems the only one that can discharge caps so far, russian meter is not ready, but it seems they are going to update it to be able to discharge caps too.

For the money they could have included 4 digit display, it seems too basic even for me.


The ESR Mciro is nice, the resolution is better, it can measure tantalum (mall caps etc.) but the stability is questionable. I would like to buy a meter with 0.1% resistors, capacitors etc.

Due to the nature of the meters themselves more than two digits after the dot is pointless, they're not accurate enough to give you three decimals or more of precision. What's the point of giving you 4 digits if the last is a random value which depends on temperature, how the probe cable is laid out on table, what electronics you have around and so on...

If you want that much precision, you have to go with kelvin clips (probes with two wires), and/or isolated up to the probe tip, and you have to go with a different method of measuring the ESR.

The LCR meters mentioned in this thread can do it, they have the correct probes, they can use the L part of the LCR meter to get a more accurate ESR value and so on.

But it depends on the budget, as I said several times already. If you want something that will tell you if a capacitor is bad, the cheap meter is good.
If somehow it makes you happy to know the exact ESR and you have money to waste, or you may need a LCR meter in the future, then go for the more expensive stuff.

I wonder what components ESR70 used compared to ESR micro 4? Is there a comparison somewhere? Is there review of these two meters side by side? Where the reviewer is intelligent enough to measure same caps 3, 4 times so make sure the result is stable? All I see are kids playing with their new toys on youtube.

In the youtube video i posted for ESR70, in the description, there's a link to the forum where the reviewer posted have high res pictures of the meter insides.

I guess I could open up my esr micro and snap some pictures of the insides but I'd rather not waste my time.

Mastech 5308 defect:
http://radiodvor.ru/novosti/pribory/Mastech-5308-defect

Defect in ESR-micro v4.0, made from 16.12.2010 to 15.01.2011
http://www.istpit.ru/showthread.php?p=281

Do you feel better if you can't find a comment about a faulty Peaktech? Would you find any comment if nobody bought it, for example?

The Mastech MS5308 is not faulty, it's not a defect of the unit itself. If you had bothered to watch the video review or the ebay link I posted, or the eevblog thread, you would have read that the power adapter they sent with the unit was faulty. It was producing too much noise thus affecting the meter when running on the adapter only.

If you use batteries or power it from a linear power supply, or use a classic transformer power supply to give it 9-12v, it will work great without batteries too.

Here's the second video from the same guy reviewing the Mastech where he describes the problem with the power supply: http://www.youtube.com/watch?v=hA_0GnNO_2A

If you waste my time here, I'd appreciate it if you at least check the links I put otherwise it's just a one sided conversation and I'm not gonna bother replying anymore.

[budm]

Re: how to find bad caps if they measure/look good??

You have to ask yoUrself on what you want to do with it, you want to verify that the cap you just remove from the board is bad compared to the new good quality cap you will be using, or you are are doing incoming QC on the cap you will be using in your products? How much details spec of the bad cap that you have so you know if it is within the spec or not? To me, I use it for comparing of the good caps to the suspect bad caps that I just pull off the board, but in the end, you will end up replacing the set of caps on the board with better one at the end of the job any way, the meter is just for vrification tool to tell you that you are correct that the circuit does not work due to bad cap with high ESR

[Per Hansson]

Re: how to find bad caps if they measure/look good??

It kinda feels like you are beating a dead horse here, but I still thought it worth mentioning that even good ESR meters like the Russian Micro ESR & Bob Parker ESR meters can be fooled.
Since the testing voltage and current are so low a bad cap can show good values...

https://www.badcaps.net/forum/showth...344#post286713

[smile]

Re: how to find bad caps if they measure/look good??

If you waste my time here, I'd appreciate it if you at least check the links I put otherwise it's just a one sided conversation and I'm not gonna bother replying anymore.

I have no intentions to waste your time, sorry if it seems that way.

That happens with other meters as well. Uni-T has meters that are designed by various engineering teams, some are awful, with glass fuses, with traces going through places they shouldn't go and all that, while other meters are excellent for the money and designed nicely. For example, I have a Uni-T UT61E that looks great inside.

Yes I agree that there are good models, the EEVblog reviews many multimeters and clearly shows the good, bad points on them. I hope that ESR meter will be reviewed someday so that similar questions I have now could be answered by simply watching a video.

[mariushm]

Re: how to find bad caps if they measure/look good??

Here's fresh video, Mastech MS5408 reviewed and tests made, showing the values in comparison with Peak ESR:

http://www.youtube.com/watch?v=1ewbA35-Gts

[smile]

Re: how to find bad caps if they measure/look good??

Thank you for the link to the review, I wonder how the soldering job in his meter looked like but he did not open it up

The comment you made on youtube is questionable, while true that the mastech measures capacitance at the same frequesncy as ESR and for ordinary caps the value is wrong (not every cap is LOW ESR like you said).

But it becomes 2 step manual process. When Peak 70 ESR does this automatic.

For the industry standard of measuring caps ESR at 100KHZ you will get wrong information on the capacitor using mastech, you then have to switch the frequency and measure capacitance again. Or did I understood it wrong?

[mariushm]

Re: how to find bad caps if they measure/look good??

The other reviewer he mentioned (and I posted a link to that video in this thread but again you probably didn't check the video) did open it and showed the insides.

Peak ESR and most microcontroller based meters that also do capacitance, measure the esr using an AC current and then they just charge and discharge the capacitor and use that discharge time to measure capacitance.

A LCR meter measures the capacitor inside a circuit along with other components, and uses a different type o capacitance measuring method. So the capacitance is always calculated at the frequency you set on the meter.

A LCR meter is also a bit more accurate, as you can see in the video.. while peak esr uses - i guess - a simple square wave at 100kHz, the mastech uses a perfect ac sine wave at 100khz.

The mastech reported in the video 4.64 or something while peak esr measured 4.4 or thereabouts, which is fine, a good enough approximation of the esr, because as i said, if you expect the cap to be low esr than 4.4 is definitely too much.

"while true that the mastech measures capacitance at the same frequesncy as ESR and for ordinary caps the value is wrong (not every cap is LOW ESR like you said). "

But that's just not true. If you'd put that general purpose capacitor he tested with in a switching power supply, the capacitance would just not be there. The capacitor would behave more like an inductor.

The guy that did this video is not an expert, he knows the basics but he learns some other things as he's "on the ride", and generally he does a great job correcting himself or making clarifications in future videos if he gets something wrong

To further clarify things... see this page here, read the text and look at the nice graphs: http://www.eevblog.com/forum/project...ance-analyzer/

Depending on how they're made, the chemistry, all that, some capacitors work better than others at high frequency.
Some of the more general purpose capacitors, when made to run at high frequency, behave more like an inductor

You can see at the graphs how both esr and impedance change as the frequency is increased... it's only normal for the capacitance to vary accordingly.

[smile]

Re: how to find bad caps if they measure/look good??

The other reviewer he mentioned (and I posted a link to that video in this thread but again you probably didn't check the video) did open it and showed the insides.

I watched both videos, that is why I asked this, I wanted a comparison between two meter build quality.

"while true that the mastech measures capacitance at the same frequesncy as ESR and for ordinary caps the value is wrong (not every cap is LOW ESR like you said). "

But that's just not true. If you'd put that general purpose capacitor he tested with in a switching power supply, the capacitance would just not be there. The capacitor would behave more like an inductor.

I'm sorry perhaps my english is really bad, I wanted to say that with mastech you first need to switch the meter to 100kHz measure esr then, switch to say 100Hz or 120Hz and measure capacitance. It's a 2 step process more accurate but it would be nice if it could be selected like semi auto mode.

While peak mesures with simply discharging caps, it show everything automatically.

I checked the bad cap thread
https://www.badcaps.net/forum/showthread.php?t=388
Downloaded some datasheets, and what do you know. ESR is listed only for low ESR caps, some manufacturers list their ESR at 1khz or anything else not 100khz. So it seems in those cases peak could not be used as the value can't be compared to actual datasheet. You can't switch the frequency on peak even to a lower one like 100Hz, or 1khz, 10kHz I wonder why?

Sure if you have mastech then it is possible to test at any frequency they specify in datasheet. But some do not specify it at all. What to do then?

Regular caps don't have esr listed too, can't they be checked?