ESR 400V & 450V caps?

[60 oldjohn]

Can anyone tell me what a maximum ESR for a good 400v 47uf CapXon should be?

John.

[Marconi_MPT4]

Does the CapXon have a series identifier such as KM, KW, KC, or KF etc?

Rich

[60 oldjohn]

Hi Rich, KY105c P1430 It is out of a PS board from LED TV that will not switch on. Show red for 10seconds then green 10 seconds red.... Before I go to the trouble of replacing cap and all the assembly, just wondered if this was lightly to be the cause.

John.

[Radio Wrangler]

It's fair possibility.

Look up that value in the data sheet of a reputable brand (Nichicon, Nippon Chemi-con, Rubycon, Panasonic) and see what their spec is. Measure and compare your suspect one and see how far off the ideal it is.

David

[60 oldjohn]

New cap 450v 0.03 R original cap 400v 0.13 R

John.

[Sideband]

Rubycon are excellent capacitors.

I have a feeling that CapXon were suspect from a few years ago. Wasn't that the manufacturer that apparently got hold of an incorrect formula from another company and then produced a load of dud caps??

[Marconi_MPT4]

Hi John,
Looked up several data sheets past and present for the CapXon KY series and none so far provide ESR values (!). Interesting these capacitors only have a rated 2000 hour life span.

Might be worth checking for any other CapXons lurking in the PSU as this type of fault is often associated with expired capacitors in and around the regulated +5V (or 3.3V these days) supply. Normally they bulge but have had a few recently that gave no external indication of failure.

Rich

[jamesperrett]

Originally Posted by Marconi_MPT4

Hi John,
Interesting these capacitors only have a rated 2000 hour life span.

That's almost certainly measured at maximum temperature. The life span should be much longer at lower temperatures.

I bought some similar 450V 100uF Multicomp capacitors (CPC code CA08629) which all show an ESR of around 0.5 ohms on my Chinese component tester with a Vloss of 0.5%. The old capacitor actually showed a lower ESR of 0.2 ohms but a higher Vloss of 0.9%. One PSU was working intermittently with the old capacitor in place while another wouldn't work at all but both worked fine with the new replacements so something was obviously different when high voltages are used.

[Maarten]

Originally Posted by Sideband

Rubycon are excellent capacitors.

I have a feeling that CapXon were suspect from a few years ago. Wasn't that the manufacturer that apparently got hold of an incorrect formula from another company and then produced a load of dud caps??

I think it was indeed one of the manufacturers, but that scandal was only one factor during a limited number of years roughly 20 years ago in the somehwat wide spread failure of capacitors and the formula was very specific for low voltage low ESR capacitors.

That said, Capxon high voltage capacitors aren't particularly prone to failure, and high voltage capacitors in equipment that hasn't seen 10 years of continuous usage are also not the first on the list of suspects, though they can occasionally fail.

The OP might be better of posting the brand, type and possibly other details of the set. It might even be going into protection for defective backlight.

[Maarten]

Originally Posted by jamesperrett

That's almost certainly measured at maximum temperature. The life span should be much longer at lower temperatures.

Life span in modern electrolytics is almost always specified at max ambient temp and max ripple. For every 10 degrees below max temp, life span will double. Applying less ripple will also increase life span by some arbitrary curve that isn't usually found in datasheets. Less ripple means less heating of the core, so that factor probably largely depends on thermal conductance from the core to outside and from the ambient temperature.

1000 hours is the lower limit for budget series and cheap brands; 2000 hours can even be considered some form of "long life".

[trobbins]

And for the CapXon KY that is 2,000hrs at 105C, not 85C (at which the life could be estimated at 8,000hrs, or 1yr continuous), and that life is for a change in parameters that may not even be noticed in the application, so actual ok service life in even a warm environment starts to look like a decade at least.