just got my blue meter...have a couple questions

[shibby_cbs]

so i got the meter today and went on testing a few bad projector psu's i had waiting to be fixed. all caps had an esr rating well below the limit but there were a couple that were pretty much right at the line and one way higher than it should be indicating a bad cap. but what about the ones that are right on or close to the limit line. do these need replaced?...at what point does a cap esr reading warrant a bad cap?...anything over the line?...anything close to the line?...also i read somewhere here on the forum about replacing caps with other caps that arnt the exact same value...i wasnt able to find this thread again but is there some rule to follow when doing this or a chart i can consult?..thanks for any and all responses and i look forward to cruisin the forums with you guys as i plan on bein around a while as i dive deeper into this electronics repair venture

[bigbeark]

Re: just got my blue meter...have a couple questions

so i got the meter today and went on testing a few bad projector psu's i had waiting to be fixed. all caps had an esr rating well below the limit but there were a couple that were pretty much right at the line and one way higher than it should be indicating a bad cap. but what about the ones that are right on or close to the limit line. do these need replaced?...at what point does a cap esr reading warrant a bad cap?..

I would suggest that if the ESR shown on the meter is more than 70% of the "limit", then that cap should be replaced.

Anything at or near the limit is toast. The cap still works, but it is putting an unnecessary load on the system.

A fully recapped board works SO much better than one with semi-okay caps.

[shibby_cbs]

Re: just got my blue meter...have a couple questions

I would suggest that if the ESR shown on the meter is more than 70% of the "limit", then that cap should be replaced.

Anything at or near the limit is toast. The cap still works, but it is putting an unnecessary load on the system.

A fully recapped board works SO much better than one with semi-okay caps.

got it thanks...then thats what ill do. also...any tips getting an esr reading on caps over 250v?

[PCBONEZ]

Re: just got my blue meter...have a couple questions

so i got the meter today and went on testing a few bad projector psu's i had waiting to be fixed. all caps had an esr rating well below the limit but there were a couple that were pretty much right at the line and one way higher than it should be indicating a bad cap. but what about the ones that are right on or close to the limit line. do these need replaced?...at what point does a cap esr reading warrant a bad cap?...anything over the line?...anything close to the line?...also i read somewhere here on the forum about replacing caps with other caps that arnt the exact same value...i wasnt able to find this thread again but is there some rule to follow when doing this or a chart i can consult?..thanks for any and all responses and i look forward to cruisin the forums with you guys as i plan on bein around a while as i dive deeper into this electronics repair venture

ESR in data sheets is given as a specific value, so where are you coming up with some range that has a limit?
[Just asking...]
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Also note that the ESR given in data sheets is the worst case where the cap is considered to be within factory specs.
Caps [especially new ones] with ESR a bit lower than shown in their data sheets is quite normal.
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[This applies to Low ESR caps.]
Those few manufacturers that say anything about it consider caps failed if ESR has doubled.
While that might be true when considering only the cap, that doesn't mean a given circuit will work right if the cap's ESR doubles.
.

[bigbeark]

Re: just got my blue meter...have a couple questions

ESR in data sheets is given as a specific value, so where are you coming up with some range that has a limit?
[Just asking...]
-
.

I suspect he is referring to the table of UF value, voltage, and maximum ESR that comes with ESR meters, intended as a general guideline. I know the Blue meter has such a chart, I've seen references to it here. I don't have the Blue meter, but my meter has such a chart on the front face of the meter.
Not perfect at all, but gives a definite idea of the scope of the recapping job
required. If at a minimum, you were to replace all the caps that are suspect, you would reasonably expect the board to boot and load an operating system.

[PCBONEZ]

Re: just got my blue meter...have a couple questions

I suspect he is referring to the table of UF value, voltage, and maximum ESR that comes with ESR meters, intended as a general guideline. I know the Blue meter has such a chart, I've seen references to it here. I don't have the Blue meter, but my meter has such a chart on the front face of the meter.

AFAIK those charts are based on GP caps as in TV sets and so forth.
Not useful for Low ESR caps at all.
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Also the +/-20% Tolerance stated for caps only applies to the uF.
.

[mockingbird]

Re: just got my blue meter...have a couple questions

Is this bluemeter the same as Rusmike's meter? What are your opinions on multimeters that have built-in capacitance testing. Crude, perhaps, but is it useful at all?

[PCBONEZ]

Re: just got my blue meter...have a couple questions

They are both based on [reworks of] Bob Parker's ESR meter.
AKAIK insofar as the ESR function the only differences are kind of leads and cosmetics.
I have one of Bob Parker's Mk-II version which I prefer as the leads connect via banana plugs so I can change leads when I feel the need.

"multimeters that have built-in capacitance testing"
I've never had one as I have a few actual capacitance meters around.
From what I've seen most don't have much of a uF range.
If you can find one with an appropriate range I imagine they are fine.
.

[Krankshaft]

Re: just got my blue meter...have a couple questions

The only DMMs with decent uf range capacitance functions are the high end (non graphing) Flukes my 87-5 can do up to 9,999uf at 1% accuracy. I'm curious what the accuracy of Rusmikes is? I'm not talking it down just curious.

During my DMM purchase research earlier this year. I quickly discovered how most meters had very low capacitance ranges some maxed out in the high pF range while others went to a whopping 10uf.

I came to the conclusion that unless you're willing to shell out big bucks for a DMM with a large capacitance range you're looking at either a used LCR meter or a homebrew rig if you need capacitance.

On the usefulness of a cap meter. Occasionally a caps ESR can be fine but it's capacitance can drop this is where a cap meter would be more useful however this occurrence is fairly rare.

On the the usefulness of the meters with the max capacitance in the pF range I personally find them useless. Because in most cases the caps with these tiny values are virtually trouble free.

[mockingbird]

Re: just got my blue meter...have a couple questions

$320 for that model, I checked... I would rather have ESR measurement than capacitance for sensitive applications, but I can see where capacitance measurement would be useful.