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Just barely, and only over a fairly long time period (months). ThereHi , after changing many capacitors that were leaking on the power
supply board , cannot turn on the television.
Power LED is blinking.
Can these 2200uF capacitors damaged something else on the board ?
hereOn Mon, 24 Jan 2011 10:57:29 -0800 (PST), benitos <pothier@cae.ca
wrote:
Hi , after changing many capacitors that were leaking on the power
supply board , cannot turn on the television.
Power LED is blinking.
Can these 2200uF capacitors damaged something else on the board ?
Just barely, and only over a fairly long time period (months). There
are many different types of electrolyte. Some are mild acids, but
most are water or alcohol based.
http://en.wikipedia.org/wiki/Electrolytic_capacitor#Electrolyte
Just clean up the mess, replace the big caps (even if they haven't
blown up yet), and be done with it. If you have an ESR tester, it
might help identify which caps are the likely culprits.
More:
http://www.badcaps.net/forum/showthread.php?s=f467f8a95fa3c34842bd4bbc39d50a2e&t=13045
esr meter !is an esr meter repository to choose from a schematic to build your own
is an esr meter repository to choose from a schematic to build your own
esr meter !
http://kripton2035.free.fr/esr-repository.html
If one takes that literally, the scope probes /will/ be connected directlySet the audio gen to about 100kHz and connect the output
across the electro under test -- then connect the scope probes
directly to the same cap (not the generator). You should see a
small voltage at 100kHz on the scope.
Nope, it IS connected directly to the generator.Set the audio gen to about 100kHz and connect the output
across the electro under test -- then connect the scope probes
directly to the same cap (not the generator). You should see a
small voltage at 100kHz on the scope.
If one takes that literally, the scope probes /will/ be connected directly
to the generator.
Did you leave something out?
Set the audio gen to about 100kHz and connect the output
across the electro under test -- then connect the scope probes
directly to the same cap (not the generator). You should see a
small voltage at 100kHz on the scope.
If one takes that literally, the scope probes /will/ be connected
directly
to the generator.
Did you leave something out?
Nope, it IS connected directly to the generator.
And the capacitor across both.
Skimming through a bunch of ESR meter schematics, this seems to be theOn 1/24/2011 6:40 PM, William Sommerwerck wrote:
Set the audio gen to about 100kHz and connect the output across
the electro under test -- then connect the scope probes directly
to the same cap (not the generator). You should see a small
voltage at 100kHz on the scope.
If one takes that literally, the scope probes /will/ be connected
directly to the generator.
Did you leave something out?
Nope, it IS connected directly to the generator.
And the capacitor across both.
You see a reduced value of signal due to the ESR of the capacitor
vs the source impedance of the signal generator.
Pretty simple.
Not direct reading, but accurate comparison.
Retch.On 1/24/2011 6:40 PM, William Sommerwerck wrote:
Set the audio gen to about 100kHz and connect the output
across the electro under test -- then connect the scope probes
directly to the same cap (not the generator). You should see a
small voltage at 100kHz on the scope.
If one takes that literally, the scope probes /will/ be connected directly
to the generator.
Did you leave something out?
Nope, it IS connected directly to the generator.
And the capacitor across both.
That would work if you knew the exact source resistance of theYou see a reduced value of signal due to the ESR of the capacitor
vs the source impedance of the signal generator.
Nothing is simple, but these examples might help:Pretty simple.
Not direct reading, but accurate comparison.
Jeff
Skimming through a bunch of ESR meter schematics, this seems to be the
game plan for most of them:
Oscillator --> attenuator --> cap under test --
op amp/comparator --> rectifier --> meter
(osc. is usually around 50-100 kHz)
(the attenuator delivers only millivolts to the cap being tested, avoiding
electrolytic polarity issues and any semiconductor junction resistances)
So the cap goes before the scope leads?"Jeffrey Angus"
William Sommerwanker
Set the audio gen to about 100kHz and connect the output across the
electro under test -- then connect the scope probes directly to the
same cap (not the generator). You should see a small voltage at
100kHz on the scope.
If one takes that literally, the scope probes /will/ be connected
directly
to the generator.
Did you leave something out?
Nope, it IS connected directly to the generator. And the capacitor
across both.
** Connection of the scope direct to the electro cap is important.
Otherwise, the inductive reactance of the cable from the generator ( at
100kHz ) to the cap becomes included in the scope display of ESR - and
is often more than the ESR of a good cap.
..... Phil
** What kind of POS scope do you have ???If you have 1 volt of output swing, and an assumed function generator
output impedance of 50 ohms, the short circuit current will be about
20ma. Shove that into a 0.5 ohm electrolytic cazapitor, and you'll
measure maybe 10mv across the cazapitor. That's kinda hard to see.
** Utter bollocks !!!Of
course you could supply more than 1 volt but then you will have some
problems trying to use this technique without removing the cazapitor
from the PCB.
** Just set it to max and that's it for ESR testing.For what it's worth, I did it this way until I bought an ESR meter.
Later, I decided to actually measure the output impedance of my
function generator. The data sheet said 50/75 ohms, but it was
anywhere between 30 and 100 ohms depending on the position of the dial
and output step attenuator.
** More bollocks.If you look carefully at the schematics supplied below, most of them
put a known series resistance at the output of the generator section
to the cazapitor. You could do the same thing with the function
generator. 100 ohms in series with an alleged 50 ohms will not
magically make the method more accurate, but it will reduce the error
to a tolerable level.
Tek 2247A. I have several others, but that's the one I like to use."Jeff Liebermann"
If you have 1 volt of output swing, and an assumed function generator
output impedance of 50 ohms, the short circuit current will be about
20ma. Shove that into a 0.5 ohm electrolytic cazapitor, and you'll
measure maybe 10mv across the cazapitor. That's kinda hard to see.
** What kind of POS scope do you have ???
Read what I wrote again. I said "1 volt of output swing" which means10mV rms = 28.3 mV p-p.
Mine goes down to 2mv/div. About 1/3 of that is noise. My guess(tm)My scope goes down to 5mV per division - then has a 5X mag switch if
needed.
How so? If the cazapitor happens to appear across a semiconductorOf
course you could supply more than 1 volt but then you will have some
problems trying to use this technique without removing the cazapitor
from the PCB.
** Utter bollocks !!!
As your own example proves.
Lets just say I don't like running my test equipment flat out into anFor what it's worth, I did it this way until I bought an ESR meter.
Later, I decided to actually measure the output impedance of my
function generator. The data sheet said 50/75 ohms, but it was
anywhere between 30 and 100 ohms depending on the position of the dial
and output step attenuator.
** Just set it to max and that's it for ESR testing.
True, except that the variation between what's considered a good and aIf you look carefully at the schematics supplied below, most of them
put a known series resistance at the output of the generator section
to the cazapitor. You could do the same thing with the function
generator. 100 ohms in series with an alleged 50 ohms will not
magically make the method more accurate, but it will reduce the error
to a tolerable level.
** More bollocks.
The vast majority of electros have less than 1 ohm ESR values - so any
error in the calculated drive current is TINY in comparison to a 50 ohm
source.
Huh? I've taken bags of brand new electrolytic caps and tested themThe variation in ESR values between new electros of the same type is far
more.
Who said anything about 0.1uF?With any ESR meter there are 'gotchas' to beware of. Any
ceramic caps in parallel with a 'lytic will mask the true condition of
the 'lytic.
** Totally insane BOLLOCKS !!!!!
A 0.1uF ceramic has an impedance of 16 ohms at 100KHz - while a typical
100uF electro has an impedance of 0.16 ohms at 100kHz. That is 100 times
less !!!
Imbecile.
If it reads bad, it IS but if it reads good it might not be.
** Only time that is ever true is if the electro is shorted - internally
or
externally.
May times I've run into boards with many caps of the same value.
If one of those is bad I change all of that value figuring if one is
bad the others aren't far behind.
** Not a bad idea - if all the electros have been subjected to the same
temps for the same times.
Also, the output caps in SMPS need to be nearly perfect.
** Well, that may be so in some cases.
But designers usually leave a margin for component variations and some
deterioration in electros.
Once the ESR of an electro rises by more than 50%, it may be time for
replacement - cos it is now gonna keep rising.
Not likely to do much better than the MUL3333 ESR meter from MatOn 1/24/2011 5:20 PM Jeffrey Angus spake thus:
On 1/24/2011 6:40 PM, William Sommerwerck wrote:
Set the audio gen to about 100kHz and connect the output across
the electro under test -- then connect the scope probes directly
to the same cap (not the generator). You should see a small
voltage at 100kHz on the scope.
If one takes that literally, the scope probes /will/ be connected
directly to the generator.
Did you leave something out?
Nope, it IS connected directly to the generator.
And the capacitor across both.
You see a reduced value of signal due to the ESR of the capacitor
vs the source impedance of the signal generator.
Pretty simple.
Not direct reading, but accurate comparison.
Skimming through a bunch of ESR meter schematics, this seems to be the
game plan for most of them:
Oscillator --> attenuator --> cap under test --
op amp/comparator --> rectifier --> meter
(osc. is usually around 50-100 kHz)
Gots to build me one someday ...
(the attenuator delivers only millivolts to the cap being tested,
avoiding electrolytic polarity issues and any semiconductor junction
resistances)
--
Comment on quaint Usenet customs, from Usenet:
To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.
If you have 1 volt of output swing, and an assumed function generator
output impedance of 50 ohms, the short circuit current will be about
20ma. Shove that into a 0.5 ohm electrolytic cazapitor, and you'll
measure maybe 10mv across the cazapitor. That's kinda hard to see.
** What kind of POS scope do you have ???
10mV rms = 28.3 mV p-p.
Read what I wrote again. I said "1 volt of output swing" which means
1 volt peak to peak.
** My ESR test idea uses a sine wave.Also, all the ESR test circuits I've seen use a square wave,
** Then 10mV rms is easy to see and measure.My scope goes down to 5mV per division - then has a 5X mag switch if
needed.
Mine goes down to 2mv/div.
** Think again - Mr bullshitartist.I think the X5 or whatever magnification on your unspecified model
scope usually refers to the horizontal sweep, not the vertical gain.
** Cos the residual voltage on the cap under test is only 10 mV !!!!!!!!!!!Of
course you could supply more than 1 volt but then you will have some
problems trying to use this technique without removing the cazapitor
from the PCB.
** Utter bollocks !!!
As your own example proves.
How so?
** Just set it to max and that's it for ESR testing.
Lets just say I don't like running my test equipment flat out into an
AC short circuit (the cap under test).
** Absolute NONSENSE !!If you look carefully at the schematics supplied below, most of them
put a known series resistance at the output of the generator section
to the cazapitor. You could do the same thing with the function
generator. 100 ohms in series with an alleged 50 ohms will not
magically make the method more accurate, but it will reduce the error
to a tolerable level.
** More bollocks.
The vast majority of electros have less than 1 ohm ESR values - so any
error in the calculated drive current is TINY in comparison to a 50 ohm
source.
True, except that the variation between what's considered a good and a
bad electrolytic is sufficiently small that source impedance makes a
difference.
** Yes.The variation in ESR values between new electros of the same type is far
more.
Huh?
Also, your math is wrong hotshot.
** No it ain't.
Go get fucked you stupid cunt.
Yeah, it is. 0.1uF to 100uF is 1000 times, not 100 as you wrote.
"** Totally insane BOLLOCKS !!!!!Quote from you
I said nothing of parallel cap values.