the HN would not just be taller but also be 10mm diameter versus 8mm on the KZJ so keep that in mind, you'd run into trouble if the current caps are already touching each other. but yes, otherwise those would be a very good replacement.

the poly cap you found is an SMD variant actually.

Ok thanks , I did not realize the Poly I found was a SMD
The HN actually has the same diameter 10x25 mm of the KZJ 10x16 mm so diameter will not be an issue as they are identical .

I was thinking if I'm going to the trouble of replacing caps that I'm better of using new caps ( Poly) and not NOS .
The problem I have is knowing which poly can I use to replace this KJZ ?

Ok , I found the correct poly on mouser that's actually a Radial and not a SMD https://au.mouser.com/ProductDetail/United-Ch … KFZ5rYqmgIC8%3D
2200uF 6.3V ESR 10 mOhms Ripple 5560 mA 10x12mm
Can I use this poly to replace my KZJ ?

i'd go for the polys then if you don't mind the higher price. the HN would probably be fine too though - there's certain standards in capacitor datasheets for how and how long they can be stored and i'd expect mouser would be following those. i also don't see NOS there anywhere but rather EOL, so they could be still fairly recent parts in theory.

i always understood that "half capacitance rule" as being more related to the fact that you simply couldn't get those high capacitance numbers as on wet caps for the longest time, yet lower capacitance polys could still be used because the VRM switching frequency on newer boards is high enough for this not to matter. this fairly recent thread seems to confirm that notion.

If the capacitors are used in a VRM or step down regulator it´s best practice to raplace them by some similar electrolytic capacitor model of the same type, a very low ESR Aluminium electrolytic with a high temperature range and a similar ripple current at high frequencies.
I would use this Panasonic "FM-A" here (assuming the hight 0f 25 mm is not a problem):
https://industrial.panasonic.com/ww/products/ … els/EEUFM0J222L

Using a different type with even lower ESR as the original incurs a risk of overloading other components or interfere with the proper function of the whole circuit.

majestyk wrote on 2021-03-27, 07:30:

If the capacitors are used in a VRM or step down regulator it´s best practice to raplace them by some similar electrolytic capac […]
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If the capacitors are used in a VRM or step down regulator it´s best practice to raplace them by some similar electrolytic capacitor model of the same type, a very low ESR Aluminium electrolytic with a high temperature range and a similar ripple current at high frequencies.
I would use this Panasonic "FM-A" here (assuming the hight 0f 25 mm is not a problem):
https://industrial.panasonic.com/ww/products/ … els/EEUFM0J222L

Using a different type with even lower ESR as the original incurs a risk of overloading other components or interfere with the proper function of the whole circuit.

Poly caps are known to work as replacements for ultra low ESR VRM applications. Select based on voltage withstand, lead spacing, ripple current, and ESR. Capacitance can be substantially different and not cause issues as the caps are usually at or close to self resonance.

The biggest problem with substituting caps of differing ESR is the changed feedback loop causing instability.

you'll be surprised once you figure out those SMD ones are actually identical to the radial ones, aside from the little bit of plastic and short bent pins.

I'm in the process of replacing all capacitors on a few power supplies I have here. I already desoldered all of them. How do I know if the original ones were low ESR or not? I do not see any interesting marks on them. Thanks!

Search their datasheets if they are from a reputable brand. If they're not, Panasonic FR series never failed me when it came to re-capping power supplies. Generally speaking, the caps in the primary side are general-purpose ones and secondary side are low-ESR but not ultra-low like those on motherboard VRMs.

I remember reading in more than one place that polymer caps are not a suitable replacement in PSUs designed around aluminum electrolytics, so make sure to 'do your homework' if you're gonna take this route...

quicknick wrote on 2021-04-05, 23:36:

Search their datasheets if they are from a reputable brand. If they're not, Panasonic FR series never failed me when it came to re-capping power supplies. Generally speaking, the caps in the primary side are general-purpose ones and secondary side are low-ESR but not ultra-low like those on motherboard VRMs.

I remember reading in more than one place that polymer caps are not a suitable replacement in PSUs designed around aluminum electrolytics, so make sure to 'do your homework' if you're gonna take this route...

I think that might be an issue, they range from no brand (that I can see) to teapo and fuhjyyu, nothing seems to be even "decent".

you should definitely be able to see a brand and usually series on the sleeve. if this is 90s stuff i would probably go with panasonic FC/chemicon LXZ or something like that with a bit higher ESR than panasonic FR, as you're already likely to undercut the original ESR and some PSU types are said to become unstable when you go too low on ESR. and on that note forget about polymodding PSUs, it's not reliable.