ESR reading?Good/ BAD ESR value? surface mount capacitor cause ripple wavy LCD?

[[email protected]]

I have a LCD monitor that is wavy and produces more ripple as the
resolution goes up.
I have just replaced 2 surface mount capacitors, their ESR ( using Dick
Smith meter) readings are 88 and 97 respectively, so there must be bad
..
However, the monitor is still wavy after the repair.

There are couples of 16V 10uF that goes around 10-17, and according to
the chart on the meter , good rating should be around 1.6

Question1: What ESR value is considered to be bad? How many times the
bad one has to be larger than the good value on the meter's chart?

Question2: Is it possible that the ripple is caused by something other
than the dying capacitors?

 

[ray13]

What ESR value is considered to be bad?

Depends on the Value of capacitance as you can tell from the meter
chart.

How many times the bad one has to be larger than the good value on the meter's chart?

The times depends of the type of cap, there are low ESR caps and low
leakage caps. Towit the higher ESR the less ripple that cap can take
out compared to a low ESR. of the same value of capacitance. The Lower
the ESR the better.

Good luck
KC8OJU
Raymond Borowiak

 

[[email protected]]

Instead of trying to pass/fail a electrolytic based only on the chart
it is wise to compare the readings with several new caps from your
parts bin..... same value obviously.
electricitym
..
..

 

[427Cobraman]

Are you zero-ing the meter and discharging the caps before taking your
readings?

 

[Sam Goldwasser]

Are you zero-ing the meter and discharging the caps before taking your
readings?

Also may be confused in-circuit if there are inductors nearby.

I usually consider a difference of 2:1 significant, not 10 or 20 percent. Your
10:1 is definitely bad if this was measured out of circuit.

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[[email protected]]

I measured a new one, Panasonic FK serires 16V 10uf(Low esr), the ESR
reading is 1.4, and the old one are about 10-17(the cap's brand is
unknown)

The good value on the chart is 1.6.

Should i replace them if they are at least 6 times larger than the
value on the chart?

To consider a cap is bad ,How many times the ESR value has to be
larger than the good one ?

 

[Chris Jones]

I measured a new one, Panasonic FK serires 16V 10uf(Low esr), the ESR
reading is 1.4, and the old one are about 10-17(the cap's brand is
unknown)

The good value on the chart is 1.6.

Should i replace them if they are at least 6 times larger than the
value on the chart?

To consider a cap is bad ,How many times the ESR value has to be
larger than the good one ?

When the ESR is too high, the circuit doesn't work That is the
criterion that really matters in the end.

Some circuits are more sensitive to the ESR of the capacitors than other
circuits. An increase of 10 times means that it is worth replacing the
cap, even though this is no absolute guarantee that it will fix your
monitor. The ESR is sufficiently high that it *might* be the problem, and
at least when you have replaced it, you will have ruled out that component
and you can move on. Also if you don't replace it, then it might stop
working soon anyway.

Chris

 

[Arfa Daily]

I measured a new one, Panasonic FK serires 16V 10uf(Low esr), the ESR
reading is 1.4, and the old one are about 10-17(the cap's brand is
unknown)

The good value on the chart is 1.6.

Should i replace them if they are at least 6 times larger than the
value on the chart?

To consider a cap is bad ,How many times the ESR value has to be
larger than the good one ?

Although I've said on many occasions that the Dick Smith meter gives
unambiguous readings, that statement has to be tempered with a degree of
experience. Interpreting ESR readings is a mixture of art and science, and
if you deal with the subject a lot, you will rapidly get a " feel " for bad
caps. As others have said, a lot depends on capacitor type, and where it is
located in the circuit, as to whether its going to cause trouble. Surface
mount electros tend to have a higher ' natural ' reading than their
corresponding-value conventional types, so it's often a good plan to do a
comparison with a known-good similar type.

I use a Dick Smith virtually every day, and the chart on the front is, in
general, a very good guide, but it should be used as just that, not a
definitive good / not good indicator for all cap types. In normal
circumstances, I would consider anything giving a reading of twice or more
the *expected* value, to be at least on its way, if not truly u/s. Other
indicators help with the suspicion of a bad cap. These are -

Its proximity to anything that gets hot

The ripple ( or other 'AC' ) circumstances under which it normally works,
and how hot this causes it to normally run

To some extent, the normal voltage that's across it, compared to its rated
voltage

Arfa

 

[Bob Parker]

That's an excellent explanation, mate! You wouldn't believe how
many times I've been asked "What's a good and bad ESR reading?" as
though it's a hard and fast value for a capacitor like its working
voltage is.
I'm going to make it into a text file and send it to people when
they ask me that question. Thanks!!

Regards
'Terry'

 

[Arfa Daily]

That's an excellent explanation, mate! You wouldn't believe how
many times I've been asked "What's a good and bad ESR reading?" as
though it's a hard and fast value for a capacitor like its working
voltage is.
I'm going to make it into a text file and send it to people when
they ask me that question. Thanks!!

Regards
'Terry'

Hi Bob

Ha ! Fame at last ... Please feel free. What's with " Terry " ?

Arfa

 

[Bob Parker]

Hi Bob

Ha ! Fame at last ... Please feel free. What's with " Terry " ?

Arfa

Just a nickname I pinched from the Minder TV series....

Bob

 

[Arfa Daily]

Just a nickname I pinched from the Minder TV series....

Bob

Duh !! How could I be so dumb ... ???

Arfa

 

[Tom MacIntyre]

Just a nickname I pinched from the Minder TV series....

Bob

Minder...he was cool!

Tom

 

[Arfa Daily]

Minder...he was cool!

Tom

I always loved the whole prog, from the first episode of the first series,
to the last of the last - hence my tribute to the main character Arthur
Daley. Dave, the barman, always used to call him " Arfa " so Arfa.Daily is
my little tribute to a great piece of British TV.

Arfa