Are these caps low ESR?

[nima158]

I replaced my capXon caps in my monitor with these nichicons and there's a high pitched noise which i suspect is from overheating due to one of these caps being high in ESR?

Black ones are 820uF 25v.

Brown one is 330uF 25v.

Thanks.

[mockingbird]

Re: Are these caps low ESR?

My guess is the ESR for the Nichicon HV caps you used is too low. Too low an ESR causes coil whine from what I understand.

FYI, HV is miniaturized HD. The ESR for your particular cap is 0.019.

[PCBONEZ]

Re: Are these caps low ESR?

Mockingbird probably called that right.
You may have shifted a frequency or rerouted some ripple through a coil.
[Plainbill would never buy it though. "Ignore the specs. Just use FM for everything."]

Anyway..
Hard to say without knowing more about what you did.
What did Capxon series did the HV replace?
.

[nima158]

Re: Are these caps low ESR?

Mockingbird probably called that right.
You may have shifted a frequency or rerouted some ripple through a coil.
[Plainbill would never buy it though. "Ignore the specs. Just use FM for everything."]

Anyway..
Hard to say without knowing more about what you did.
What did Capxon series did the HV replace?
.

I believe the old CapXon caps were the GL series, for both 820uF and 330uF caps. (Ive attached pictures)


As for what exactly I did, I replaced the following on the SyncMaster 216BW PSU:

5x CapXon 820uF 25V
1x CapXon 330uF 25V

with the nichicons i mentioned before.


I appreciate the help, Thanks again.

[PCBONEZ]

Re: Are these caps low ESR?

Usually noise in these is caused by a loose coil or transformer winding in which the length of the loose part happens to be a harmonic of a frequency passing through it.
- It vibrates.
Heat-up and cool-down cycles can sometimes make it appear or disappear by moving the winding a bit.
Changing the frequency may start a loose one vibrating that didn't before.
'Brapping' a coil or transformer can loosen a winding that wasn't loose before.
[Some kinds of transformers/coils can be fixed by adding a dab of varnish.]

There's also a more unusual condition called "singing MOSFETs" among other things which amounts to vibrating transistors. If you didn't have it and now you do that would mean some frequency changed.
I'm not suggesting that is the problem. It's pretty unusual.

Those things usually don't cause any problems other than the user maintaining sanity.

If you can power this up WITHOUT zapping yourself.....
Take a piece of soft tubing [so you don't hurt your ear] and use it like a stethoscope to see if you can tell where the noise in coming from for sure.
If the tube is non-conductive you can touch things enough to block the end of the tube which sometimes will cause a tone change or, if it's the wrong part the noise in your ear should get a little quieter.
Tubing [soft type] for automotive windshield washers works great.
So does aquarium air tubing if it's not too big
3/16 to 1/4 inch ID is about right.

On to the caps...

GL 330uF 25v 10mm , Ripple -740 mA , ESR - 0.082 ohms
PW 330uF 25v 10mm , Ripple -760 mA , ESR - 0.090 ohms
Raising ESR is not a good thing but 0.008 ohms [10%] isn't going to kill it or anything.
The GL specs are likely that far off anyway... LOL

GL 820uF 25v 10mm , Ripple -1460 mA , ESR - 0.043 ohms
HV 820uF 25v 10mm , Ripple -2180 mA , ESR - 0.019 ohms
More than 1/2 might be a problem. Isn't always. Just sometimes.
-
Look at where the 820's went in the circuit and thinking about where Ripple would go consider if any are likely to pull more Ripple through a coil or transformer.
If the make-shift stethoscope suggests that is the area the noise is coming from then that/those cap[s] are what you need to 'de-rate' back closer to original specs.
.

[mockingbird]

Re: Are these caps low ESR?

There's also the chance that the caps he didn't replace have a very high ESR because they have failed.

Replace -ALL- the caps, not just the ones that have bloated. I think most Samsung logic boards you SMD polymers so no need to touch those.

[nima158]

Re: Are these caps low ESR?

Usually noise in these is caused by a loose coil or transformer winding in which the length of the loose part happens to be a harmonic of a frequency passing through it.
- It vibrates.
Heat-up and cool-down cycles can sometimes make it appear or disappear by moving the winding a bit.
Changing the frequency may start a loose one vibrating that didn't before.
'Brapping' a coil or transformer can loosen a winding that wasn't loose before.
[Some kinds of transformers/coils can be fixed by adding a dab of varnish.]

There's also a more unusual condition called "singing MOSFETs" among other things which amounts to vibrating transistors. If you didn't have it and now you do that would mean some frequency changed.
I'm not suggesting that is the problem. It's pretty unusual.

Those things usually don't cause any problems other than the user maintaining sanity.

If you can power this up WITHOUT zapping yourself.....
Take a piece of soft tubing [so you don't hurt your ear] and use it like a stethoscope to see if you can tell where the noise in coming from for sure.
If the tube is non-conductive you can touch things enough to block the end of the tube which sometimes will cause a tone change or, if it's the wrong part the noise in your ear should get a little quieter.
Tubing [soft type] for automotive windshield washers works great.
So does aquarium air tubing if it's not too big
3/16 to 1/4 inch ID is about right.

On to the caps...

GL 330uF 25v 10mm , Ripple -740 mA , ESR - 0.082 ohms
PW 330uF 25v 10mm , Ripple -760 mA , ESR - 0.090 ohms
Raising ESR is not a good thing but 0.008 ohms [10%] isn't going to kill it or anything.
The GL specs are likely that far off anyway... LOL

GL 820uF 25v 10mm , Ripple -1460 mA , ESR - 0.043 ohms
HV 820uF 25v 10mm , Ripple -2180 mA , ESR - 0.019 ohms
More than 1/2 might be a problem. Isn't always. Just sometimes.
-
Look at where the 820's went in the circuit and thinking about where Ripple would go consider if any are likely to pull more Ripple through a coil or transformer.
If the make-shift stethoscope suggests that is the area the noise is coming from then that/those cap[s] are what you need to 'de-rate' back closer to original specs.
.

LOL, quite the idea with the stethoscope, I should also mention that the high pitched noise only sounds after 10-20 minutes after the monitor has been running, and doesn't go away until I turn it off for a few minutes to "cool down" which is what led me to think it was overheating.

I guess the most "relevant" culprit is a loose transformer, correct?

There's also the chance that the caps he didn't replace have a very high ESR because they have failed.

Replace -ALL- the caps, not just the ones that have bloated. I think most Samsung logic boards you SMD polymers so no need to touch those.

It seems plausible, however does that include the large 450-volt cap?

Also, sorry for the noob question, but what exactly is an "SMD" polymer?

[PCBONEZ]

Re: Are these caps low ESR?

I guess the most "relevant" culprit is a loose transformer, correct?

Sounds like it because as the transformer warms up the wire gets [or 'wants' to] a little longer which can cause it to move if it's loose.

It seems plausible, however does that include the large 450-volt cap?

No.
That caps smooths the ripple just after the input bridge rectifier but before the SMPS section [switching section] of the PSU.
It is not exposed to the higher switching frequencies [up roughly around 100kHz].

Also, sorry for the noob question, but what exactly is an "SMD" polymer?

SMD = Surface Mounted Device.
Just means it doesn't use through-hole mounting.
Both lytics and polymers can come that way.
.

[nima158]

Re: Are these caps low ESR?

Sounds like it because as the transformer warms up the wire gets [or 'wants' to] a little longer which can cause it to move if it's loose.


No.
That caps smooths the ripple just after the input bridge rectifier but before the SMPS section [switching section] of the PSU.
It is not exposed to the higher switching frequencies [up roughly around 100kHz].


SMD = Surface Mounted Device.
Just means it doesn't use through-hole mounting.
Both lytics and polymers can come that way.
.

Oh, Okay thanks, I'll do the stethoscope idea you mentioned earlier on the weekend, and I'll let you guys know where exactly the sound is coming from.

Thanks alot!