ESR Meters.
 

Asking the blindingly obvious question. Where does one obtain a reliable ESR meter worth buying.
I ask as an enthusiastic amateur who is slowly climbing the learning curve. I’ve looked on that well know auction site but they seem to be Chinese with some really descriptive problems or in kit form which I don’t feel competent to assemble.

As an aside, I belong to the ‘don’t recap unless you’ve got to’ wing. If I find I do (mainly on A77’s/b77’s) I only do one board at a time. I’ve found to my cost in the past that doing a blanket recap is not a good idea. If a replacement component/cap is faulty when installed I do not have the necessary experience (which takes years) to find the ****** thing. I’m fortunate in having a friend who is very experienced (started working with valves in the early fifties, military and domestic) who has the ability to guide me, uncannily sometimes, in the right direction but even he is not infallible. Bit by bit is the safest option. As the man said “a little knowledge is a dangerous thing”.🙄

Re: ESR Meters.
 

When I wanted an ESR meter time was in short supply, so I just ordered a Peak one from Farnell. Not cheap but well made, neat, no problems or worries, quick to get and does the job perfectly.

You can certainly beat the price by shopping around if you have the time and inclination.

Big hint with all ESR meters.... make sure capacitor is discharged before connecting!

David

Re: ESR Meters.
 

I picked up my ESR meter for twenty quid at an audiojumble, and very good it is too. Leaving such flukes out of the equation, I'd say the Peak ESR70 is a good bit of kit. I swear by early models of their component and semiconductor testers, which Peak will still service and upgrade.

Re: ESR Meters.
 

I can highly recommend this LCR meter from Japan.
It's the best bang for the buck available today.
It measures ESR among other things.
Frequency is settable from 100 Hz to 100kHz.
Accuracy is very good.

https://rover.ebay.com/rover/0/0/0?m...2F161965793927

Cheers
Ray

Re: ESR Meters.
 

Good video here from EEVBlog

https://youtu.be/ji-UT7HJm0Q

Re: ESR Meters.
 

The Peak tester discharges capacitors before testing unlike the cheapies, the instant demise of some has been reported before. I wouldn't want to do it deliberately though.

Re: ESR Meters.
 

I agree the peak is safer in use.
But it's hard to beat the DE-5000 LCR for its vast range of functions, and cheaper than the Peak.
It's got 4 wire capabilities and can also do resistance to 0.001 ohms.

Re: ESR Meters.
 

Do you have an ocsilloscope and function generator? I didn't buy an ESR, but used a scope and generator to make ESR tests.

https://www.youtube.com/watch?v=115erzCCxgE

Re: ESR Meters.
 

The best ESR meter I have ever used was the one designed by Bob Parker. I have the kitset version of it made by Silicon Chip, available from Altronics with a lovely black housing and Red LED's, but they come in other forms:

https://www.altronics.com.au/p/k2574-esr-meter-kit/

(everyone with these falls in love with them)

https://www.ebay.com/itm/AnaTek-Blue...e6b6:rk:1:pf:0

Not 100% sure where to get these Bob Parker meters in the UK, but I'm sure they will be around somewhere. They work on a low level pulse principle, great for in circuit testing. Generally I have been disappointed with the sine wave principle meters.

Re: ESR Meters.
 

Still got a very old but excellent Bob Parker one. The times it has bailed me out on modern power supplies,too many to mention.

Certainly should it ever fail then go for Peak. First class helpful company.

Re: ESR Meters.
 

My vote would be for the Peak excellent unit from a good UK company and to date completely reliable. Also good support, I also have an older Bob Parker one but I prefer the Peak. The Peak is often available with 10% discount to Radcom Readers and other groups using a code.

Re: ESR Meters.
 

If you want cheap as chips, the little Chinese component testers on ebay are pretty good and display ESR. In terms of accuracy, they're not precision instruments but seem pretty accurate from what I've found. Theyre on PCB's but are pretty much assembled, just needing the battery connector and component clamps soldering on.

Not sure how useful ESR meters are for vintage radios etc though. You want to see leakage and capacitance more than anything surely? High ESR capacitors will also read higher capacitance on multimeters that can measure that, IIRC

Re: ESR Meters.
 

I think high ESR would decrease a capacitance reading. High leakage will increase it.

ESR is still relevant for the smoothing caps and output valve cathode decoupling caps, though.

Re: ESR Meters.
 

ESR meters are a 'one trick pony' and in recent years, have tended to be eclipsed by Chinese 'multi-testers' which are so much more versatile. ESR meters used to be a popular homebrew project, such as the Television Magazine one in the late 1980s and the one that I posted on the forum back on 2010 (which ran for four years with more than 60,000 views). But time moves on and Chinese Multi-testers and now so cheap and versatile, that it makes a homebrew one pointless, and buying a commercial ESR meter questionable, compared to a multi-tester.

Unlike Multi-meters, where there are safety issues to consider, and where some enthusiasts strive for a level of accuracy quite beyond what's called for by hobbyists, those issues don't really apply to ESR meters. It's unnecessary to know the ESR value to three decimal places, and it's easy enough to check the calibration of the meter using close tolerance resistors if in any doubt about the result of a reading.

As a rough rule of thumb, for capacitors in a Switch Mode Power Supply, (which few of us dabble with), up to 0.5 Ohm is considered good, for general use, from 0.5 to 3 Ohms, then from 3 to 10 Ohms the cap in question should be compared to a new good one. If the ESR of the new one is well below the one under test, it should be replaced. Anything over 10 Ohms, chuck it in the bin. I've attached below a pic of a typical analogue homebrew ESR meter dial to show what I mean.

I have two homebrew ESR meters which are now replicas of the past, even though they perform well - one from TV magazine, and the one I made back in 2010 at this (now closed) forum thread: https://www.vintage-radio.net/forum/...ad.php?t=54367

If nothing else, that thread shows what a popular tool ESR meters are considered to be.

Coming up to date, I've got two Chinese Multi testers, which test capacitors including ESR, but also test resistors, inductors diodes and transistors, including FETs. I also have two Peak Atlas Transistor testers - an aging DCA50 and a more recent DCA55 - an impulse buy when Maplin had them of offer for about £20. The Peak ones work well enough on silicon and germanium transistors, but compare poorly with the Chinese testers for FETs. As seen in the second and third Pic below, when a P Channel FET is under test, the DCA50 thinks it's a diode, the DCA 55 can't identify the source, drain and gate, but the Chinese tester in Pic 4 does so, and gives some data too. (It as a cheap unboxed meter for under a tenner which I boxed up).

So, if you buy an ESR meter, that's what you get. (Depending on the meter, it may also give you the capacitance value). They all work on a similar principle - a low voltage at 100kHz or so applied to the cap under test.

On the other hand, you could buy a much more versatile (and probably much cheaper) multi-tester such as the one at this link below, which - in my experience - when testing transistors, does a better job than my Peak DCA55, and also tests inductors, resistors etc. Many come with an infuriating ZIF socket, but this one comes with test leads, but also has a plug-in ZIF socket to use instead of the three test leads, if that's what's preferred. It's just one of a plethora of offerings:

https://www.ebay.co.uk/itm/MK-328-TR...-/122500532594

Just a final point, many if not most electrolytics on transistor radios such as Roberts, Bush and Hacker from the late 50 - 60s, especially physically small ones, will have dried out long ago, and if you put a cap tester across them, will often look like low value resistors. If the radio seems to be working, there's a temptation to 'let sleeping dogs lie' and leave them in place, especially given that they're on SRBP printed circuit boards where it's easy to damage the tracks when de-soldering. However, in some situations, leaving duff caps in place won't just degrade the sets performance, it can destroy the output transistors and seriously shorten battery life.

So, for aging transistor sets, a multi tester will tell you if an electrolytic cap has a high ESR, high leakage, and if it's still functioning as a capacitor or has morphed into a low value resistor. If it's a blue Philips, you might just as well switch your soldering iron on before the test meter. To be fair, what else can we expect of components that are almost 60 years old?

The last picture shows a 680µF capacitor in the emitter circuit of a Roberts R505 output stage. As can be seen, neither ESR nor capacitance came into it - the tester saw it as a 0.53 Ohm resistor. In other words, a dead short from the emitter of the AC187 to ground. It, and it's companion AC188, were getting too hot to touch but survived the ordeal.

Hope that's of interest and use.

Re: ESR Meters.
 

I'm not sure on the precise relationship, I was told a few years back some high capacitance readings I got were the result of high ESR. I don't know that for a fact. I tested a few waxies recently that were showing double their capacitance on the multimeter, yet next to no leakage even at 350v DC though, which was surprising.

Re: ESR Meters.
 

It's fairly easy to understand if you think about how a capacitor meter works.

Basically, they apply a known current to a capacitor, and time how long it takes to charge to a particular voltage.

Now, if there is leakage, then some of the known current is "robbed" by the leakage resistance, meaning that there is less current to charge up the capacitor. This means the capacitor takes longer to charge. And that is why the meter will report a higher value of capacitance. Simple!

Obviously in extreme cases the leakage will prevent the capacitor from reaching the target value, and the meter will probably say "Overload" or similar.

How about ESR?

Bear in mind that the charging current is tiny - perhaps in the order of a milliamp, perhaps quite a bit less. The current flows through the ESR, and a voltage is developed across it. But it will also be tiny, as ESR is measured in fractions of ohms. A cap that has high ESR might still measure 10s of ohms, and that is still a very low value in the context of the charging current from the tester.

So unless the capacitor has terrible ESR, the ESR won't make a difference to the reading of capacitance. And as the ESR rises, then so does the voltage across it, which in turn means that the capacitor under test will reach the target voltage sooner, which will result in a lower reading, not a higher one. Although in practice it's unlikely to be noticeable given the usual tolerance of electrolytic caps.

In practice, as a capacitor degrades, the ESR starts to rise long before the capacitance falls away - ESR is a measure of how conductive the electrolyte remains. For the capacitance to start to fall, sections of the electrolyte need to become non-conductive so as to reduce the area of overlap that forms the capacitance. And as for leakage, this is a breakdown of the oxide layer on the foils - this is more to do with chemistry (which I don't pretend to understand!), but most caps made in the last 50 years seem to be very good at resisting this (no pun intended).

Hope this helps,

Mark

Re: ESR Meters.
 

I agree that the Chinese multitesters are more versatile, but they are not without issues. As has already been mentioned, the Chinese kits fail with a charged capacitor. OK, you could argue that they are cheap enough to not have to worry about that, but personally, I'd rather not consign the whole unit to landfill and have a replacement shipped all the way from China every time I make a mistake with a charged cap.

These Chinese testers are based on the work of a German engineer - it's a shame he rarely receives any credit for his efforts. I believe that he shared his project for non-commercial use only - I don't know for sure, but would be really surprised if the various Chinese suppliers have approached him for permission to commercialise his work. https://www.mikrocontroller.net/arti...ansistortester

The Peak Atlas meter does not attempt to read to 3 decimal places; it gives readings to the same number of decimal places as my Chinese multitester.

What you are paying for with the Peak Atlas - apart from supporting a UK company, of course - is the discharge function and the support should something go wrong.

It should be noted that Peak Atlas update the firmware for their products fairly often. For example, they have improved the reading of germanium transistors in light of feedback from customers. You will have relatively old firmware in that Maplin DCA55.

You might think that, but I really wouldn't want to make assumptions about everyone on this forum. There are a lot of TV enthusiasts here, for example. Even if the set lacks an obvious switched-mode power supply between the mains input and the rest of the set, it will have a line output stage, which is very much a switched-mode supply. Many modern switched mode supplies are "flyback converters" - you might see the connection there ;)

As I've just said in another thread, the blue axial Philips capacitors do sometimes fail - and I've read about your one experience with that R505 before - but they have a near-100% reliability record in Hacker and Roberts radios in my experience. I never change them until I have good reason, and it really frustrates me when people do "blanket changes" on them. That is just misguided prejudice.

Yet experience shows that these same caps were "change on sight" in the CRT monitors I used to repair in the '90s. The lifespan of a capacitor is a product of how it's used, as well as the initial quality. Transistor radios are a very easy environment for a capacitor, unlike a modern power supply or a CRT monitor, to pick two examples. It's all about context...

There are plenty of "change on site" caps out there in older transistor sets, such as the royal blue "Daly" types, or the bright red "Elkomold", to name but two. They are guaranteed to be leaking heavily, although their ESR and capacitance is usually OK.

In cool-running transistor radios, leakage is the usually problem - ESR is normally academic, and so is capacitance, given the wide range of tolerances back then.

Unfortunately, a cap with mild leakage won't show up as such on a multitester. I've just done some testing with a 1000uF cap and a resistance decade box - even with 100 ohms in parallel with the cap, the tester still reports the capacitance value and gives no indication that there is a leakage problem. Whereas the Peak Atlas says "in circuit" - it does that until you get above 1k. Still not ideal, but leakage is a tricky one - it must be measured separately, and I'm not aware of many affordable commercial options for that. A bench power supply and a resistor is the easiest way of doing it, but that obviously takes a bit of setup time.

Electrolytic capacitors failing short-circuit is relatively rare, and can happen at any time. Lack of use is more likely to cause the problem than age or brand. Certainly, there is no data to suggest that Philips axial capacitors are more prone to it than others - I must have seen tens of thousands of them over the years, and can't recall seeing one that had started to leak, let alone go short. They usually sit there gradually going high-ESR - depending on the surrounding temperature and ripple current - and depending on the circuits they are working in, they can continue to function really quite happily in that state. When discussing ESR and its importance or otherwise, it's really important to look at the surrounding circuit conditions. It's often not important.

In practice, it is possible to get by without an ESR meter - I managed for decades - by making observations of the faulty circuit. This requires an understanding of the circuit, and some experience, but it's much more intellectually satisfying that random testing or random parts swapping. It's not always viable for mechanical or commercial reasons, but if I can, that's what I still do. The same arguments apply to semiconductor testers too. But not everyone has the ability to do this, and given the low price of these testers - even the Peak Atlas, in real terms - then why not? It's always nice to be able to confirm the diagnosis.

You won't need one if you're only fixing transistor radios, but for something like a tape machine, which runs slightly warmer than a simple radio, then capacitors will fail, and an ESR meter is a useful way to accelerate the fault-finding process - but remember, it's not the Holy Grail; other testing and thinking will still be required. If you can afford it, get the Peak Atlas. The Chinese kits are better than nothing, but get a couple - and glue a strip of metal to the front panel, near the contacts, to provide a convenient way to discharge caps before testing them.

Sorry for the length of this post.

Mark

Re: ESR Meters.
 

No need for an apology. Lengthy posts with good quality information are always appreciated.

Alan

Re: ESR Meters.
 

I’ve got an old Wayne Kerr 4225 automatic LCR bridge, which is configured nicely as a component tester. I used it the other day to test some cheap electrolytics which had just come in the post. First one on test showed a slightly low value for C and an unimpressive value for ESR, but then I went off to answer a phone call. Coming back ~30 minutes later, I was pleased to see that the readings had changed quite favourably, especially the decrease in ESR. Then I remembered I’ve seen this before with both brand new and NOS electrolytics; it’s really best to charge and then discharge them, just to remind them that they are capacitors. The testers usually only apply mV levels of bias, so that they don’t affect semiconductors when doing on-board tests, so charging and discharging on a suitable psu, to near their maximum voltage, can influence the measurements quite a lot.

B

Re: ESR Meters.
 

Thanks for the in depth explaination Mark, that's lit a few lightbulbs for me, I will remember that :idea: