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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sat 18, 2017 4:03 pm 
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Quote:
The name of this site is Antique Radios.com

Why would we be discussing "solid state stuff of recent manufacture" ?


The need for small ESR testers arrived with glycol based capacitor electrolytes in 1970, 47 years ago. As noted above, glycol filled electrolytics tend to fail open or high ESR, in contrast to water based ones which fail leaky or shorted. In 1970 Germanium transistors were already obsolete and silicon junction transistors were in their heyday. Some ICs were around but mostly in exotic commercial and military gear.

I was one of the few people tinkering with antique radios in 1970--I started as a kid. At that time, a 47-year-old antique radio was something like a Radiola III or an Aeriola from 1923. Nobody thought of them as "recent manufacture."

Best regards,
Chris

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 19, 2017 5:36 am 
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Chris108 wrote:
Quote:
The name of this site is Antique Radios.com

Why would we be discussing "solid state stuff of recent manufacture" ?


The need for small ESR testers arrived with glycol based capacitor electrolytes in 1970, 47 years ago. As noted above, glycol filled electrolytics tend to fail open or high ESR, in contrast to water based ones which fail leaky or shorted. In 1970 Germanium transistors were already obsolete and silicon junction transistors were in their heyday. Some ICs were around but mostly in exotic commercial and military gear.

I was one of the few people tinkering with antique radios in 1970--I started as a kid. At that time, a 47-year-old antique radio was something like a Radiola III or an Aeriola from 1923. Nobody thought of them as "recent manufacture."

Best regards,
Chris


I started as a kid in the late fifties, and could fix the very early stuff, and did so because some
people wanted them to work, but were laughed at by mainstream service, now well into TV.

However, I broke into jobs that stuck, because I could fix transistor radios. That was not
because I had a big brain. It was because 'mainstream service' avoided them.

I suspect my eyesight was much better than the geezers fixing TVs. :D

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 19, 2017 12:44 pm 
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The simplest method I have seen for go / no go for NP caps is in my 1938 tube tester. That applies around 225DC at a safe current via a series Neon. If the cap does not leak there is a brief flash as the cap charges & then the Neon extinguishes. With over 99% of old paper caps that won't happen & the intensity of the glow is merely an indication of just how bad the leak is.

My other method for leakage of NP types is an insulation tester that can get down to 100V and up to 1KV: That gives a reading in ohms. This being based on the fact that a good NP cap should not pass DC.

+1 on most times with a Wax Paper cap & many oil filled types; It just not worth the effort. 60's Car radio's are the ones I find with the really dried out electrolytic caps: Cars get very hot here in the summer sun.

Marc


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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 19, 2017 7:41 pm 
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Marc's point about insulation testers going down below 100 volts is well taken.

The Chinese insulation testers, are meggers that only have higher voltage ranges.

I do have a 25 volt real hand cranked megger. (rare). Even so there are warnings
about using it, aimed at the 'people' who would need such an instrument.

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 19, 2017 10:40 pm 
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I have the feeling that the Supermarket here, that still sells an updated version, saw a niche market. Not everything needs 500V and for HV NP caps in tube radio's: Ideal. Tag & test requires 500V here but, why not a more versatile device. That's why I bought one.

The reformer I have built is capable of stepping Volts and has provision for current measurement. That means that it can measure current passing through a leaking NP cap as well as Ecaps. some may not have realised that, You measure the voltage drop across a resistor. E.g. 1000 Ohms 1V = 1mA (10 Meg DVM)

Marc


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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 19, 2017 10:43 pm 
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There is some solid state Marantz and McIntosh, antiques all, that are worth HUGE money.
Sansui, the list goes on.

Radio and antique, seems to belong here.

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 19, 2017 10:48 pm 
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Leigh wrote:
solid state stuff of recent manufacture. The name of this site is Antique Radios.com

Why would we be discussing "solid state stuff of recent manufacture" ?

- Leigh



unless we have a "good before" date in the rules. Solid state ain't new no more. But there is sites better suited to that, AudioKarma.
problem is, there is little forum activity on most other sites, only ARF has this traffic and resource of experts.
Like Leigh :D

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Tue 21, 2017 12:24 am 
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Ok, help me out with this one please. As I recall, capacitors are two metal conductors, separated by a dielectric. Any losses through the capacitor would be between the plates, so technically in series with them. Failure modes in terms of electrolytes, are primarily from the electrolyte drying out, and thereby changing the capacitance ( less capacitance ) the electrolyte drying out and the foil conductors shorting out, or water getting into the capacitor and making a better conductor and overheating the device to failure. So how can there be a parallel loss mode? Am I confused ?
We test them for capacity, leakage and esr, all in a series circuit, just displayed in different values, right ?

Happy Thanksgiving everyone. We are so blessed !

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Tue 21, 2017 2:18 am 
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Bob S wrote:
Failure modes in terms of electrolytes, are primarily from the electrolyte drying out, and thereby changing the capacitance ( less capacitance ) the electrolyte drying out and the foil conductors shorting out, or water getting into the capacitor and making a better conductor and overheating the device to failure.

It is not that "water gets into the capacitor and makes a better conductor". It is that the dielectric film on the surface of the foil is damaged, perhaps simply due to the capacitor sitting unpowered for a long time, and so current flows through the electrolyte like a resistor. This is "leakage". It heats the electrolyte and either dries it out or in some cases boils it into steam, followed by the capacitor exploding from the steam pressure.

Bob S wrote:
So how can there be a parallel loss mode? Am I confused ?
We test them for capacity, leakage and esr, all in a series circuit, just displayed in different values, right ?

Leakage is not a series circuit:
Jim Mueller wrote:
On the other hand, leakage is a parallel resistance.

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Tue 21, 2017 4:03 am 
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Leakage is from one conductor to the other in the capacitor, through the dielectric, how can it not be a series mode. It may be measured in megohms, diagrammed as if the resistance was in parallel with the capacitor.


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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Tue 21, 2017 4:11 am 
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Bob S wrote:
Leakage is from one conductor to the other in the capacitor, through the dielectric, how can it not be a series mode. It may be measured in megohms, diagrammed as if the resistance was in parallel with the capacitor.
Leakage is in parallel with the capacitor because it will conduct DC current.

ESR in contrast will not conduct DC current, so it's in series with the capacitor.

- Leigh

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Tue 21, 2017 4:16 am 
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Bob S wrote:
Leakage is from one conductor to the other in the capacitor, through the dielectric, how can it not be a series mode. It may be measured in megohms, diagrammed as if the resistance was in parallel with the capacitor.

As you say, it is diagrammed as if the resistance was in parallel with the capacitor. Therefore it is not in series with the capacitor.

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Tue 21, 2017 5:05 am 
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By definition, a dielectric does not allow an electric current to flow, however
everything does have a specific resistivity.

However space is not a thing, despite having an impedance of 377 ohms.


Has the full half hour argument been paid for ? :D

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Tue 21, 2017 2:10 pm 
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The series loss part is called dissipation (or dissipation factor, tan-delta, or power factor). The reason certain materials are known as "dielectric" is because they have molecular dipoles which change position under the influence of an electristatic field. Like tiny springs you can wind them up with electric charge and then when the field is removed they unwind and return energy to the system. But just as it is with mechanical springs, you never get all the energy back that you put into a dielectric due to molecular friction. The dissipation is the energy that is lost, ultimately as heat.

Leakage is modeled as a resistace in parallel with the plates of the capacitor.

From this it should be apparent that dissipation only occurs when the molecules in the dielectric are moving. So unlike leakage, you cannot find it with a DC ohmmeter of any type. It takes an AC test voltage or at least a voltage that varies somehow. As you would expect, dissipation is different for each kind of dielectric, and it is frequency dependent. If the dissipation plus all ohmic losses are considered, you get the ESR, or equivalent series resistance of the cap.

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Fri 24, 2017 4:26 pm 
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If you look at a series equivalent circuit of a capacitor, you see the ESR depicted as a series resistance. It is the cumulative effects of resistive losses of the leads, terminals, conductors and dielectric of the capacitor. Leakage is DEPICTED as a parallel resistance, but is not in truth such, there is no mythical outside path for loss, only THROUGH the capacitor. So even though it is displayed that way, loss is series through the device. The dissipation factor quantifies the actual losses through the device, usually given up as radiated heat. It is the heating sometimes extreme, due to defects in the dielectric, or because of mechanical defects that cause hydrogen to be liberated from the electrolyte, thus causing the exploding of the capacitor. It is not steam that turns them into little bombs, but hydrogen.


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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Fri 24, 2017 5:24 pm 
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Quote:
If you look at a series equivalent circuit of a capacitor, you see the ESR depicted as a series resistance. It is the cumulative effects of resistive losses of the leads, terminals, conductors and dielectric of the capacitor. Leakage is DEPICTED as a parallel resistance, but is not in truth such, there is no mythical outside path for loss, only THROUGH the capacitor.


No sir. Leakage can and does include current passing through the encapsulating material, case, coating, or whatever is on the outside of the capacitor--especially when it is old and covered with film, dirt, and gunge. There have been cases where epoxies and other types of coatings have caused high leakage in capacitors due to contamination or improper formulation. It should also be noted that some capacitor coatings that were good when new have been known to become leaky over time due to reactions with chemicals or ozone in the environment, reactions with the plastic films inside the capacitors, cleaning in the wrong kinds of solvents, or molecular breakdown.

Quote:
It is the heating sometimes extreme, due to defects in the dielectric, or because of mechanical defects that cause hydrogen to be liberated from the electrolyte, thus causing the exploding of the capacitor. It is not steam that turns them into little bombs, but hydrogen.


Actually, steam and hydrogen both can result in venting or bursting of electrolytic capacitors. If the internal temperature of an electrolytic gets high enough, quickly enough for any reason, the electrolyte can turn to steam and cause the capacitor to vent. If the vent is plugged or cannot release the pressure fast enough, blowing out the rubber plugs or bursting of the cases could occur.

Hydrogen is generated when water based electrolytes undergo electrolysis. This is a normal process which contributes to the ongoing operation of electrolytic capacitors; the oxygen released combines with aluminum to form and maintain the aluminum oxide dielectric layer that enables the capacitor to work. Normally this goes on very slowly and the hydrogen atoms released gradually diffuse through the seals. However, if there's a breakdown in the dielectric layer and large amounts of current can pass, the electrolysis may produce hydrogen bubbles. Microscopic sparks due to scintillation can ignite the bubbles, resulting in a popping noise which is sometimes heard. Even higher levels of current can liberate enough hydrogen to blow the capacitor apart with a flash or flame. Fortunately this is a rare occurrence; usually the first small hydrogen bubbles which ignite disrupt the plates and short them together. That blows a fuse or burns out other components, so no more hydrogen is generated.

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Fri 24, 2017 7:25 pm 
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It's really a math thing. We can represent value and loss as either a parallel or series combination. For calculation purposes they are entirely equal. Neither one is an accurate representation of the physical device and what goes on within. Depending on what one is trying to calculate, parallel or series numbers might be preferred. As an example it's a lot easier to calculate the combined losses for parallel capacitors if you first convert to a parallel model. Then stuff just adds. After that, convert back to series model if you want series numbers. You can also express everything as conductance or using phase angle, if that better suits your needs.


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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sat 25, 2017 2:00 am 
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One "antique" application for the ESR tester is in early transistor radios and TV sets. It is easy to pick out the dead ones without removing them, a plus when dealing with the early PC boards. I have been using the Anatek meter for quite a while now, and wouldn't be without it when working on SS equipment.

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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 26, 2017 9:39 am 
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With an ESR tester, resistance testing HIGH indicates a bad cap. It is pretty useless testing a leaky cap. It can be used in-circuit, though.

With a capacitance meter, testing LOW indicates a cap that is drying out (bad). A capacitor testing way HIGH typically indicates a leaky cap. The capacitance meter can't reliably test in-circuit.

I have also used a Simpson 260 VOM to test for leakage in small value caps like micas. The process I use is to set it on the highest resistance range and put the capacitor on the meter. a good cap will go to infinite resistance within in a minute or so, a leaky one will never quite get to infinite, even after several minutes. This, too, is an out of circuit test.


Someone mentioned solid state gear. I recently repaired a Panasonic RF-3000 radio for a fellow club member, a radio that is about 45 years old. It's full of these little 1uF caps used as coupling caps throughout. All of those were bad and the larger ones were on their way out. I am now working on an RF-5000 that I own and its pretty much the same story. Good-bye old caps.


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 Post subject: Re: ESR vs Leak testing Capacitors
PostPosted: Nov Sun 26, 2017 1:31 pm 
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Several recent posts are touching on the concept of an "equivalent circuit" for a component. For example, if we have a capacitor with a simple resistive leakage, then the equivalent circuit will have an ideal capacitor in parallel with a resistor. (It cannot be series since no DC current will flow in an ideal capacitors).
Leakage is not in fact linear with voltage, so the parallel resistance is an oversimplification.

To represent losses in general, someone invented "equivalent series resistance". This is something you can only infer from measurements of the AC properties of the part.

So, a reasonably complete model of a capacitor will include both series ans parallel resistances.

But then, any component with finite length has inductance......but that's another story.....;)

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