Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default ESR meter trap


Hi,

few here would disagree that using an ESR meter is the fastest and surest way to find bad electros. If the meter reading is several times or more higher than normal, that electro must go.

This week, I saw a Fender tube amp with pretty obvious filter electro trouble that almost caught me trusting my (Bob Parker) ESR meter too much.

Under a steel cover were five, "IC" brand 22uF, 500V axial electros - from the symptoms I figured ones immediately following the rectifiers diodes must be bad. The ESR meter agreed, giving open ( 100ohms) ESR readings for two and good readings for the remaining three.

While extracting the bad pair from the PCB, I realised they were wired in parallel. The electros looked in good condition so my suspicions raised, I peeled back the case with nippers to loosen rubber bung and take peek inside..

Turned out there was NO metallic connection between the positive lead and the rest of the capacitor. The bung and lead stub simply fell off. I opened the other three and found two more in the same condition while the last was perfectly OK with all its connections in place.

The electros concerned are exactly like the ones in this pic:

http://www5.austlii.edu.au/au/legis/...9994/s268.html

The ESR meter was fooled by the fact (except for one) the caps had NOT gone high ESR, but had suffered severe corrosion of the plus leads where they entered the cap roll.

I have to agree with the author of the linked page, Illinois Capacitors have produced a bad batch and full replacement is the only smart option.




..... Phil






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Phil Allison wrote:

-------------------

** Ooops - wrong link !!!


The electros concerned are exactly like the ones in this pic:

http://billmaudio.com/wp/?page_id=267


..... Phil
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Default ESR meter trap

Actually the ESR meter was correct. The effective series resistance was provided by the gap in the wiring.
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wrote:

---------------------

Actually the ESR meter was correct.



** The good reading was **misleading** you ****ing moron.




..... Phil
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On Thursday, February 1, 2018 at 3:00:29 AM UTC-5, Phil Allison wrote:
Hi,

few here would disagree that using an ESR meter is the fastest and surest way to find bad electros.
.... Phil



Handy. Yes. Useful. Yes.

Surest? No.

Just replaced a surface mount 33uf/25v on an LG sustain EBR31872801 board which had image persistence issues and rash. The board would show improve in operation with heat added to the board. Because of the amount of sm electros on the board, I used my ESR meter with tweezer probes as removal of surface mount electros for testing is not practical. C49 33uf/25v checked about a half ohm in circuit so I moved on. The rest of the sm electros on the board checked fine as well. After I found the problem with the scope, I tested the defective cap for ****s and giggles and it read good value but 300 ohms ESR out of circuit. Before installing the replacement cap, I took an ESR reading of the empty lands and it read half an ohm. The only other cap parallel to it is C43, a 1uf surface mount film cap with an ESR of ........ 0.5 ohms.





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On Thursday, February 1, 2018 at 3:38:52 AM UTC-5, Phil Allison wrote:
wrote:

---------------------

Actually the ESR meter was correct.



** The good reading was **misleading** you ****ing moron.




.... Phil


Actually I saw the 100 ohms and assumed that means bad.

I read too fast and thought too slow. You could have worded it differently and I wouldn't have missed part of it.

Anyway, I have also heard of ESR meters being used as a low low ohmmeter to locate a short on a power supply where evereything is just hooked together.. I do have a Fluke DVM capable of that but not everyone does. i wonder if the ESR function is a bit better than that though because it might be able to pick up on some inductance. Maybe, never thought about it much.

I just use a scope for ESR.
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wrote:

------------------------

Actually the ESR meter was correct.



** The good reading was **misleading** you ****ing moron.


Actually I saw the 100 ohms and assumed that means bad.

I read too fast and thought too slow. You could have worded it
differently and I wouldn't have missed part of it.


** The Bob Parker ESR meter has an auto-ranging, two digit display that over flows above 99 ohms. It shows ESR values from 0.01 ohms to 99 ohms. The black button zeros the reading before measurements and also cycles the meter on and off.

http://i44.photobucket.com/albums/f9...SCF0045-86.jpg

The "good" 22uF, 500V electros showed readings close to 1.5 ohms while the "bad" ones were completely open. In reality, 2 of the 3 "good" electros were just about to fail open circuit.

Electro caps normally dry out and go high ESR fairly slowly, ones that test perfect one day and go DEAD the next are not playing fair.



..... Phil
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On Friday, February 2, 2018 at 4:19:20 AM UTC-5, Phil Allison wrote:
ones that test perfect one day and go DEAD the next are not playing fair.



.... Phil


Hate it when that happens.

But it's the reason we were required to Live Dead Live in the factory where I worked, to be sure power was off before doing a repair.

Live (testing a powered circuit) proves your meter works.
Dead proves your locked out circuit is safe, provided your meter didn't die in between.
Live again proves your meter was okay.


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On 2018/02/02 1:19 AM, Phil Allison wrote:
wrote:

------------------------

Actually the ESR meter was correct.


** The good reading was **misleading** you ****ing moron.


Actually I saw the 100 ohms and assumed that means bad.

I read too fast and thought too slow. You could have worded it
differently and I wouldn't have missed part of it.


** The Bob Parker ESR meter has an auto-ranging, two digit display that over flows above 99 ohms. It shows ESR values from 0.01 ohms to 99 ohms. The black button zeros the reading before measurements and also cycles the meter on and off.

http://i44.photobucket.com/albums/f9...SCF0045-86.jpg

The "good" 22uF, 500V electros showed readings close to 1.5 ohms while the "bad" ones were completely open. In reality, 2 of the 3 "good" electros were just about to fail open circuit.

Electro caps normally dry out and go high ESR fairly slowly, ones that test perfect one day and go DEAD the next are not playing fair.



..... Phil


I use (and sell) Bob's ESR meter kit (over 600 sold since 1999). The
only improvement I can suggest is to use a regular fixed range digital
ohm-meter in parallel with the leads to be sure the low reading isn't
actually a shorted component.

The meter is might also be useful for evaluating lead acid (and other)
batteries... UPS batteries for example - leave a pair of wires connected
to the battery (hanging out of the case) and check the ESR of the
battery once in a while.

John :-#)#

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John Robertson wrote:
-------------------------


** The Bob Parker ESR meter has an auto-ranging, two digit display that over flows above 99 ohms. It shows ESR values from 0.01 ohms to 99 ohms. The black button zeros the reading before measurements and also cycles the meter on and off.

http://i44.photobucket.com/albums/f9...SCF0045-86.jpg

The "good" 22uF, 500V electros showed readings close to 1.5 ohms while the "bad" ones were completely open. In reality, 2 of the 3 "good" electros were just about to fail open circuit.

Electro caps normally dry out and go high ESR fairly slowly, ones that test perfect one day and go DEAD the next are not playing fair.



I use (and sell) Bob's ESR meter kit (over 600 sold since 1999). The
only improvement I can suggest is to use a regular fixed range digital
ohm-meter in parallel with the leads to be sure the low reading isn't
actually a shorted component.


** Yes, a rare dead short in a capacitor hides its ESR from any meter PLUS caps wired in parallel have a "team ESR" that can hide bad member.


The meter is might also be useful for evaluating lead acid (and other)
batteries...



** Bob's design is most useful for all the common cells and low voltage batteries.

Lithium coin cells ( memory back up) are easily tested for ESR and a high reading means their useful life is nearly over.


..... Phil




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On Friday, February 2, 2018 at 9:55:03 PM UTC-5, Phil Allison wrote:
John Robertson wrote:
-------------------------


** The Bob Parker ESR meter has an auto-ranging, two digit display that over flows above 99 ohms. It shows ESR values from 0.01 ohms to 99 ohms. The black button zeros the reading before measurements and also cycles the meter on and off.

http://i44.photobucket.com/albums/f9...SCF0045-86.jpg

The "good" 22uF, 500V electros showed readings close to 1.5 ohms while the "bad" ones were completely open. In reality, 2 of the 3 "good" electros were just about to fail open circuit.

Electro caps normally dry out and go high ESR fairly slowly, ones that test perfect one day and go DEAD the next are not playing fair.



I use (and sell) Bob's ESR meter kit (over 600 sold since 1999). The
only improvement I can suggest is to use a regular fixed range digital
ohm-meter in parallel with the leads to be sure the low reading isn't
actually a shorted component.


** Yes, a rare dead short in a capacitor hides its ESR from any meter PLUS caps wired in parallel have a "team ESR" that can hide bad member.


Years ago I bought a portable ESR tester for my truck for working on PTVs and arcade monitors on site: http://www.drviragopete.com/resources/Eds88Aom.pdf

This meter will pick up a shorted cap or shunt circuit and display it as low DC resistance and not ESR.
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John-Del wrote:

----------------------



I use (and sell) Bob's ESR meter kit (over 600 sold since 1999). The
only improvement I can suggest is to use a regular fixed range digital
ohm-meter in parallel with the leads to be sure the low reading isn't
actually a shorted component.


** Yes, a rare dead short in a capacitor hides its ESR from any meter PLUS caps wired in parallel have a "team ESR" that can hide bad member.



Years ago I bought a portable ESR tester for my truck for working on PTVs
and arcade monitors on site:

http://www.drviragopete.com/resources/Eds88Aom.pdf

This meter will pick up a shorted cap or shunt circuit and display it
as low DC resistance and not ESR.



** Obviously, a shorted cap does not hide from an ohm meter, but will defy any meter trying to read its ESR.

Bob Parker's meter WILL read the ESR of caps in parallel with an inductor or transformer winding - not uncommon in SMPS and loudspeaker x-overs.



..... Phil
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On Thu, 1 Feb 2018 00:00:24 -0800 (PST), Phil Allison
wrote:


Hi,

few here would disagree that using an ESR meter is the fastest and surest way to find bad electros. If the meter reading is several times or more higher than normal, that electro must go.

This week, I saw a Fender tube amp with pretty obvious filter electro trouble that almost caught me trusting my (Bob Parker) ESR meter too much.

Under a steel cover were five, "IC" brand 22uF, 500V axial electros - from the symptoms I figured ones immediately following the rectifiers diodes must be bad. The ESR meter agreed, giving open ( 100ohms) ESR readings for two and good readings for the remaining three.

While extracting the bad pair from the PCB, I realised they were wired in parallel. The electros looked in good condition so my suspicions raised, I peeled back the case with nippers to loosen rubber bung and take peek inside.

Turned out there was NO metallic connection between the positive lead and the rest of the capacitor. The bung and lead stub simply fell off. I opened the other three and found two more in the same condition while the last was perfectly OK with all its connections in place.

The electros concerned are exactly like the ones in this pic:

http://www5.austlii.edu.au/au/legis/...9994/s268.html

The ESR meter was fooled by the fact (except for one) the caps had NOT gone high ESR, but had suffered severe corrosion of the plus leads where they entered the cap roll.

I have to agree with the author of the linked page, Illinois Capacitors have produced a bad batch and full replacement is the only smart option.




.... Phil




Grass Valley fiber cards had +15 -15 V power supplies where the 220uf
axial caps checked good for ESR with the Bob Parker meter in circuit
but were faulty.

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On Sunday, February 4, 2018 at 2:29:53 PM UTC-5, Chuck wrote:
On Thu, 1 Feb 2018 00:00:24 -0800 (PST), Phil Allison
wrote:


Hi,

few here would disagree that using an ESR meter is the fastest and surest way to find bad electros. If the meter reading is several times or more higher than normal, that electro must go.

This week, I saw a Fender tube amp with pretty obvious filter electro trouble that almost caught me trusting my (Bob Parker) ESR meter too much.

Under a steel cover were five, "IC" brand 22uF, 500V axial electros - from the symptoms I figured ones immediately following the rectifiers diodes must be bad. The ESR meter agreed, giving open ( 100ohms) ESR readings for two and good readings for the remaining three.

While extracting the bad pair from the PCB, I realised they were wired in parallel. The electros looked in good condition so my suspicions raised, I peeled back the case with nippers to loosen rubber bung and take peek inside.

Turned out there was NO metallic connection between the positive lead and the rest of the capacitor. The bung and lead stub simply fell off. I opened the other three and found two more in the same condition while the last was perfectly OK with all its connections in place.

The electros concerned are exactly like the ones in this pic:

http://www5.austlii.edu.au/au/legis/...9994/s268.html

The ESR meter was fooled by the fact (except for one) the caps had NOT gone high ESR, but had suffered severe corrosion of the plus leads where they entered the cap roll.

I have to agree with the author of the linked page, Illinois Capacitors have produced a bad batch and full replacement is the only smart option.




.... Phil




Grass Valley fiber cards had +15 -15 V power supplies where the 220uf
axial caps checked good for ESR with the Bob Parker meter in circuit
but were faulty.


How did they check out of circuit with the Parker meter?

Earlier in this thread I described a 33uf electro reading less than an ohm in circuit, and 350 ohms out of the circuit. The culprit was a surface mount 1uf film cap with an ESR of 1 ohm right if you can believe that across the 33uf fooling the ESR meter.
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Chuck wrote:

--------------


Grass Valley fiber cards had +15 -15 V power supplies where the 220uf
axial caps checked good for ESR with the Bob Parker meter in circuit
but were faulty.


** How uninformative.

Bob's meter tests ESR, far and away the most common, age related failure mode of electro caps.

It does not test for high leakage, being wrongly marked in the factory or installed backwards.


..... Phil



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"Grass Valley fiber cards had +15 -15 V power supplies where the 220uf axial caps checked good for ESR with the Bob Parker meter in circuit but were faulty. "

this can happen if there arew good caps in parallel with the one under test.. Like the supply itself might have a 220uF, but there could be a bunch of 1 uFs across the vcc/Vdd of a few ICs which will make it read good in circuit.

Same with banks of lytics. i have found that on many powwer supplies you oly have to bridge one in a bank to test the unit. this is from the TV days when we got in a TV that is dead, to put a bunch of caps in the PS oly to find it has screen or Tco problems and is not worth repairing. So I started just taking out one and putting one cap in its place, and I didn't even cut the leads, I let it stand up. I had a stash of caps at the bench for this purpose and saved some money, which of course was part of my job, we weren't wasting a bunch of caps anymore. Once you cut the leads it is alot harder to install on a sometimes overcrowded PC board.

Same thing applies to computer motherboards. just one will get it to work. They use alot of them because of ESR, ESL and ripple current. they might have five of them in there adding up to 10,000 uF, but a single 1,000 will get it working temporarily. One time I did that and it turns out the problem corrupted the BIOS and the system did "hang permanently" in the lingo of the manufacturer.

Everything is so cheap now servicing is all about saving money. People don't care because you can get a new one so cheap, and they don't care that the quality is even worse. Some do, or are comfortable with their old equipment. People who finally learned the whole menu on their TV or whatever, or have older high end stereo equipment. Even then you can't waste money without good reason. Some people want ten buck caps and all thin film resistors in the audio path, change them all. But they are willing to pay, the average sheeple is not.

And those cap values in uF are not that critical. And contrary to popular belief it is NOT good to up the voltage rating. the parameter that really matter are theesr and ripple current cpacity. You really think am SMPS running at 100 KHz needs 10,000 uF worht of filtering ? ****, 10 uF will do it if it can handle the ripple current and has low ESR. and the two go hand in hand. higher ESR causes an AC voltage drop which produces heat by actual power dissipation in the cap. That destroys it prematurely. they got it timed so it lasts through the warranty, and they hope not much longer. Only a few companies build everything so if you need to buy a new one they benefit anyway.

That is one of the main reasons I do not fix TVs anymore. Actually most newer equipment, **** it. Built cheap and specifically hard to service. I got tired of fighting it. And they are winning beause they REALLY control the parts ow. You can get two TVs the same model and there could be five different variations on the chassis, and almost none of the parts are interchangeable. And then there is alot of software and firmware that gets corrupted, and bad caps can cause that.
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"It does not test for high leakage, being wrongly marked in the factory or installed backwards. "

I heard of lytics marked wrong. The shop that got them said they all blew up. Turs out when they paid a bit more attention the negative lead was longer than the positive lead.

I remember a very long time ago in a small Sony TV the rectifiers were marked backwards, and so was the board ! That was a fun one.
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On Monday, 5 February 2018 10:57:40 UTC, wrote:

"It does not test for high leakage, being wrongly marked in the factory or installed backwards. "


I heard of lytics marked wrong. The shop that got them said they all blew up. Turs out when they paid a bit more attention the negative lead was longer than the positive lead.

I remember a very long time ago in a small Sony TV the rectifiers were marked backwards, and so was the board ! That was a fun one.


I once found a stuffing error I'd made many years before. A 16v lytic was in backwards on a 21v rail - had never caused any problem though.


NT
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On Sun, 4 Feb 2018 13:32:17 -0800 (PST), John-Del
wrote:

On Sunday, February 4, 2018 at 2:29:53 PM UTC-5, Chuck wrote:
On Thu, 1 Feb 2018 00:00:24 -0800 (PST), Phil Allison
wrote:


Hi,

few here would disagree that using an ESR meter is the fastest and surest way to find bad electros. If the meter reading is several times or more higher than normal, that electro must go.

This week, I saw a Fender tube amp with pretty obvious filter electro trouble that almost caught me trusting my (Bob Parker) ESR meter too much.

Under a steel cover were five, "IC" brand 22uF, 500V axial electros - from the symptoms I figured ones immediately following the rectifiers diodes must be bad. The ESR meter agreed, giving open ( 100ohms) ESR readings for two and good readings for the remaining three.

While extracting the bad pair from the PCB, I realised they were wired in parallel. The electros looked in good condition so my suspicions raised, I peeled back the case with nippers to loosen rubber bung and take peek inside.

Turned out there was NO metallic connection between the positive lead and the rest of the capacitor. The bung and lead stub simply fell off. I opened the other three and found two more in the same condition while the last was perfectly OK with all its connections in place.

The electros concerned are exactly like the ones in this pic:

http://www5.austlii.edu.au/au/legis/...9994/s268.html

The ESR meter was fooled by the fact (except for one) the caps had NOT gone high ESR, but had suffered severe corrosion of the plus leads where they entered the cap roll.

I have to agree with the author of the linked page, Illinois Capacitors have produced a bad batch and full replacement is the only smart option.




.... Phil




Grass Valley fiber cards had +15 -15 V power supplies where the 220uf
axial caps checked good for ESR with the Bob Parker meter in circuit
but were faulty.


How did they check out of circuit with the Parker meter?

Bad.
Earlier in this thread I described a 33uf electro reading less than an ohm in circuit, and 350 ohms out of the circuit. The culprit was a surface mount 1uf film cap with an ESR of 1 ohm right if you can believe that across the 33uf fooling the ESR meter.


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