Difficulty trying to match ESR of a replacement capacitor

[Ady2017]

Hi all

I am trying to find a replacement capacitor for a CapXon KM 100uF 400V. I have read that the big ones really go wrong but it is the last one left on the power supply board that has not been changed and the TV is still playing up so it is getting swapped too.

I have read that I need to find a replacement cap with the same or higher ripple and the same or lower ESR, with all the usual being matched. The ripple is easy to match but the ESR seems to be a challenge.

From the KM datasheet I have got, dissipation factor = 15% (therefore 0.15).
I have put that into the equation from here,
https://forum.digikey.com/t/calculat...-from-tan/2633
This has given me an ESR of 1.99

Looking at the equation on that site, if 'f' and 'C' are the same then if the dissipation factor is matched then then ESR will also be matched.

So I have been trying to find a 100uF 400V cap with a dissipation factor of 0.15 or less but am struggling. The best I have found so far is 0.2

Am I doing this wrong? It is confusing as the CapXon KM is not specifically listed as a low ESR capacitor but more of a high temp general purpose cap.

Thanks

[stj]

Re: Difficulty trying to match ESR of a replacement capacitor

that's on the mains input right?
so esr dont matter at 100Hz - ripple is the key - higher = better.
and if you can up to a 420 or 450v it would be better.

[Ady2017]

Re: Difficulty trying to match ESR of a replacement capacitor

Yes, it is on the main input.

I finally found one or two with a low dissipation factor but they have got a short life of about 2000 hours. Others with a slightly higher ESR are often 10,000 hours. I was expecting to find something specifically designed for power supply applications but no luck yet. I have found ones for 'ballast' applications, whatever that is?

Does anyone have any experience with the Panasonic EE series? Specifically this one,
EEUEE2G101

[stj]

Re: Difficulty trying to match ESR of a replacement capacitor

when you read "power supply applications" it will be refering to the output not the input.
for high voltage caps you should look at Rubycon - they have the biggest range,

[momaka]

Re: Difficulty trying to match ESR of a replacement capacitor

Don't worry about the dissipation factor here. Just get a quality Japanese 105C-rated cap that meets the ripple current and has the longest lifetime/endurance (usually will also have the biggest case size, so watch the dimensions.)

And if the PSU has an APFC circuit, upgrade the cap to 420V or even 450V, as stj noted. A lot of PSU manufacturers cut corners here when they use a 400V on a PSU with APFC. And as a result, most APFC PSUs with failed primary caps typically feature 400V caps.

Of course, if this is a regular flyback PSU without APFC (most likely the case, especially if the PSU is under 60W or so), then 400V cap will be fine.

[Hitto]

Re: Difficulty trying to match ESR of a replacement capacitor

Chemicon KXJ is a good replacement. Being 12.000H/105°C, it will outlast that TV. Do not worry about dissipation factory for the reasons written above.