Hi there.

If i take one board and desolder all electrolytic capacitors and measure them capacity and it`s good value is there a bad value of ESR and if i see "it" to trash the capacitor?

thanks

 

Yes there is aprox good / bad values. These are values on the front of my ESR meter.

 

if i dont have this device for thousand dollars /haha/ and work with basic 10$ esr meter between which and which is good ?

 

What is the meter you are using?

 

I have the same meter as debe post #2. It has proved to be invaluable over the years of using if in my business of servicing electronic equipment.
Do note though, that the quoted figures where taken by the designer from testing many hundreds of new capacitors and so represent an average.
Depending on the application, the actual esr maybe critical or not. High duty electrolytics in power supplies, audio amplifiers, as just a couple of examples, need to be low esr types so that they do not heat up and dry out when passing heavy currents. You really need to look at the function of a capacitor in the circuit to decide whether or not the esr reading is critical. Probably this is where years of experience helps, but as a general guide, if you have two or more of the same type and value and one has a much higher esr than the other, you can safely bin it!!
The general appearance of the capacitors is a good guide too, is it swollen? has it leaked around the pins? is it close to hot running components etc. all these things and more all good clues.

 

Hi,
No need to check the capacitor ESR in the board you desoldered. The good thing is what capacitor value you need to be use for
a given task you are doing,then such time is require to check . I meant what you need now is what you look for it.
And leave the rest,to save your effort in doing it

 

When I was screening the capacitors from a power supply for ESR, most of my new replacement caps were in the area of 1 ohm or less. A couple of the used ones were up around 30 ohms. I replaced all of them so I don’t know what the critical level was. That would depend on the application anyway, so there’s not a single answer to your question.

 

Placing capacitors in parallel is done for three reasons that I can think of--1. provides more capacitance, 2. enables capacitors to fit within a specified space, 3. reduces ESR.

 

Hi,
No need to check the capacitor ESR in the board you desoldered. The good thing is what capacitor value you need to be use for
a given task you are doing,then such time is require to check . I meant what you need now is what you look for it.
And leave the rest,to save your effort in doing it

Ummm! no, I disagree, you have no idea what the board is, and the question in the heading is .........
Are there good/bad ESR values ?

 

Ummm! no, I disagree, you have no idea what the board is, and the question in the heading is .........
Are there good/bad ESR values ?

And the answer is a resounding YES. Capacitors fail, and when they do it's usually ESR first and capacitance last, and only rarely a visible indication. This may all happen together in an instant when they explode, but it's more normal for the capacitor's increased ESR to bring down the circuit function long before there is any detectable problem with their measured capacitance or visible appearance.

 

if i dont have this device for thousand dollars /haha/ and work with basic 10$ esr meter between which and which is good ?

AFAICR: it was a cheap kit that had a pass table on the front, my old DSE might be one of them.

What's good or not is very dependent on the application - SMPSUs need very low ESR, some state of the art designs running in MHz can't tolerate even the best electrolytics.

The ESR meter speeds up service work - but only if you understand its limitations and what else is going on.

There are various clues that will help you understand what the ESR meter is telling you - any deformity of the top of the aluminium can is a warning sign, often they bulge and rupture (you don't need the meter for that one). failing electrolytics tend to run hot - sometimes that's obvious from the state of the plastic sleeve. Dodgy electrolytics tend to feel abnormally light if you take them out and hold in your hand. At the end of the day - I also test the replacement before fitting it. There really isn't any point in replacing it with something worse - even a brand new something worse!

 

For the protocol i have
TS-M8N Transistor Tester Diode Triode Capacitance ESR Meter MOSFET NPN/PNP

it`s about 10$