Teapo SC Series Datasheet: https://jamicon.teapo.com/upload/Capacitor/Series/SC.pdf
Samxon RL Series Datasheet: https://www.paullinebarger.net/DS/Samxo ... Series.pdf
Jun Fu HS Series Datasheet: https://www.junfu.com.tw/english/01_pro/downl … 21465371196.pdf

Teapo caps are garbage. Kemet polymer caps are excellent, if appropriate.

Samxon GF: https://www.paullinebarger.net/DS/Samxo ... Series.pdf

Samxon GF series was known to be failure-prone, but the rest of their caps seem okay (unless the RL series caps also failed). X-Con is Samxon's brand for polymer caps.

Teapo had an arrangement with Yageo back when they failed the most often (and before merging with Jamicon), but I don't know whether Yageo was the actual manufacturer of Teapo caps. Yageo does make electrolytic caps today, so they might have been. Yageo now owns Kemet, which makes their caps a little questionable. (Was that confusing enough?)

Elite caps are strangely expensive from US distributors, and I haven't seen many of them in stuff I tried to repair. Out of the few I've seen, none failed, but there are lots of pictures of blown ones in TV and monitor power supplies on Badcaps.

Thanks for the links and the info, guys! Yeah, most of these Teapo SC caps are leaked and bulged, but this PSU run perfectly fine for almost 15 years without any problems (I rarely shut down the machine with this PSU as it bears the role of main storage space/file server in my home network and this is the first time I opened the PSU after its refusal to power up the system last morning - actually PSU kept starting without any load), so these are not terribly bad 😀 Samxon RLs seems OK, but some of GFs are leaky too. Jun Fu HS caps (never heard of these) are all OK as they're on the small controller PCB, but I'll replace them too as their name seems very untrusty to me.

I see that all of the original electrolytic caps are with high ripple current (assume low impedance/ESR), so I'll go with available low ESR substitutes.

I have no idea if polymer capacitors are appropriate as replacement for electrolytic caps.

P.S. Ok, the new Samxon caps I can get are also from bad GF series, what about Samwha instead?

Teapo SC and Samxon GF are low ESR, you can replace those with Nichicon UPW series or equivalent.

Samxon RL and Jun Fu HS are general purpose (note the max. ripple being specified at 120Hz instead of 100KHz in the datasheets), so anything 105C rated should work there. Do try and get some decent brand though.

I would not use polymers on an old-ish power supply, their ESR is so low that it could affect the feedback circuit resulting in an unstable output. Here's what Panasonic has to say about it:

Panasonic wrote:

For Cout to minimize the output ripple voltage, low ESR is important. Accordingly, the effectiveness of low ESR conductive polymer electrolytic capacitors shown above is highly evaluated.
However, because low ESR of Cout may cause the switching power supply output to be unstable and even oscillate in some cases, attention is required.

Source: https://industrial.panasonic.com/ww/ss/technical/lc4

TheMobRules wrote on 2024-03-11, 06:14:

Teapo SC and Samxon GF are low ESR, you can replace those with Nichicon UPW series or equivalent. […]
Show full quote

Teapo SC and Samxon GF are low ESR, you can replace those with Nichicon UPW series or equivalent.

Samxon RL and Jun Fu HS are general purpose (note the max. ripple being specified at 120Hz instead of 100KHz in the datasheets), so anything 105C rated should work there. Do try and get some decent brand though.

I would not use polymers on an old-ish power supply, their ESR is so low that it could affect the feedback circuit resulting in an unstable output. Here's what Panasonic has to say about it:

Panasonic wrote:

For Cout to minimize the output ripple voltage, low ESR is important. Accordingly, the effectiveness of low ESR conductive polymer electrolytic capacitors shown above is highly evaluated.
However, because low ESR of Cout may cause the switching power supply output to be unstable and even oscillate in some cases, attention is required.

Source: https://industrial.panasonic.com/ww/ss/technical/lc4

Yes. Power supplies often need a min ESR to remain stable. Don't go ultra low ESR if not required.

TheMobRules wrote on 2024-03-11, 06:14:

Teapo SC and Samxon GF are low ESR, you can replace those with Nichicon UPW series or equivalent. […]
Show full quote

Teapo SC and Samxon GF are low ESR, you can replace those with Nichicon UPW series or equivalent.

Samxon RL and Jun Fu HS are general purpose (note the max. ripple being specified at 120Hz instead of 100KHz in the datasheets), so anything 105C rated should work there. Do try and get some decent brand though.

I would not use polymers on an old-ish power supply, their ESR is so low that it could affect the feedback circuit resulting in an unstable output. Here's what Panasonic has to say about it:

Panasonic wrote:

For Cout to minimize the output ripple voltage, low ESR is important. Accordingly, the effectiveness of low ESR conductive polymer electrolytic capacitors shown above is highly evaluated.
However, because low ESR of Cout may cause the switching power supply output to be unstable and even oscillate in some cases, attention is required.

Source: https://industrial.panasonic.com/ww/ss/technical/lc4

Thank you for these details. In this case I will not do any experiments with polymer caps. The new Samxon low ESR caps I can get are also from not so good GF series, what about Samwha instead? I'll replace Junk-Fu with some descent brand all purpose/regular caps (those are with smaller capacity 1 uF/50 V, 10 uF/25 V and 100 uF/16 V on the small controller PCB), but will it be a big problem if I replace the three Samxon RL with low ESR caps with same capacity and rated voltage - they're the ones with the lowest capacity on the main PCB: one 100 uF/16 V and two 220 uF/25 V (the rest are low ESR Samxon GF 1000 to 2200 uF/6.5 to 16 V)?

P.S. Now I see that "high ripple current" doesn't always go with "low impedance/ESR".

kingcake wrote on 2024-03-11, 06:15:

Yes. Power supplies often need a min ESR to remain stable. Don't go ultra low ESR if not required.

Understood, I will not use any polymer caps as substitutes.

analog_programmer wrote on 2024-03-11, 06:22:

Thank you for these details. In this case I will not do any experiments with polymer caps. The new Samxon low ESR caps I can get are also from not so good GF series, what about Samwha instead? I'll replace Junk-Fu with some descent brand all purpose/regular caps (those are with smaller capacity 1 uF/50 V, 10 uF/25 V and 100 uF/16 V on the small controller PCB), but will it be a big problem if I replace the three Samxon RL with low ESR caps with same capacity and rated voltage - they're the ones with the lowest capacity on the main PCB: one 100 uF/16 V and two 220 uF/25 V (the rest are low ESR Samxon GF 1000 to 2200 uF/6.5 to 16 V)?

Yeah, you should be OK using low ESR caps for the smaller ones (I suspect the 100uF/16V and 220uF/25 are used on the output of the -5V/-12V lines, pretty much anything will work there)... as long as you avoid ultra-low ESR electrolytics (which are not even produced anymore) and polymers for the reasons mentioned above you should be safe.

For the low ESR caps (SC and GF in this case) just try to find replacements that match the ripple and impedance @ 100KHz from the datasheet in addition to capacitance/voltage. More ripple tolerance is OK, and it doesn't need to be a totally strict match with the impedance, just stay in the ballpark and you'll be fine, the design of these circuits usually allows for some leeway as long as you stay between certain minimum and maximum values.

Try sticking only with good Japanese brands like Rubycon, Panasonic, Nichicon, and United Chemicon.
SamWha is -kind of- junky... about on par with Samxon GF: they'll probably last you a few good years in the PSU, if not more... but eventually, you will have to re-recap the PSU again. In contrast, quality Japanese caps will be a lifetime repair.
As for Elite... they are so-so too. I've seen them used a lot in LCD monitors, and depending on which series we are talking about, they can be anywhere from very decent to not very good. Also depends if they have been abused with heat. The ones that weren't do OK. But again, if better quality caps are available to you, I'd go with those. The price difference should be negligible.
As for Jun Fu... Junk Fu is putting it nicely. I'm not a fan of this brand.

Here are some series that should work with your PSU from the above Japanese brands:
Rubycon: YXJ, YXH, YXM, PX (general purpose series), ZLQ*, ZL*
Panasonic: FC, FK, FR*, FM*, FS*
Nichicon: PW, PS, PM, PJ, HE, HD, HW*, HV*
United Chemicon: LXZ, LXY, LXV, KY, KYB, KZE, KZH*, KZM*

* : I've used some of these in PSUs before, but their ESR may be a bit too low for some PSUs.

Just follow what TheMobRules mentioned about matching the replacements. Indeed most PSUs tend to be quite flexible in what they can take, so it's not critical to match ESR or ripple current exactly. +/- 30 to 50% for the ESR is fine. Ripple current - higher than the original would be better... but in a pinch, lower RC from a high-quality Japanese cap manufacturer will usually do fine too. And as far as capacity and voltage ratings go: anywhere you see 6.3V caps, you can safely use 10V caps and vice versa. For capacity, going a notch up or down is usually not a problem either... though it's preferable to go up if the right size is not offered - e.g. putting a 1200 uF cap in place of a 1000 uF cap. Actually, even 1.5x higher capacitance won't hurt (if anything, higher capacitance is better... within reasonable limits, of course.)

In regards to the big cap(s) inside the PSU: does it have 2x 200V caps or one (or more) 400V/420V/450V caps. The former is typically accompanied by a voltage-selector switch and means the PSU does not have an APFC circuit. The latter means your PSU does have APFC. This is important to note, because APFC tends to stress the primary caps a lot more than non- or PPFC PSUs. So if the primary cap(s) is/are not a Japanese brand from the ones mentioned above (or Hitachi), you may want to replace it too. Just note that this/these large 400V/420V/450V caps will be rather expensive. My general rule is: if the PSU will be seeing a lot of use at high load and if the original cap was only rated for 400V (and especially if it's not a Japanese brand), then it's better to replace it - preferably with a cap rated for 420V or 450V. The primary cap doesn't have to be low ESR... and you will see that you probably won't find it in the above series. For this one, it just needs to be rated for 105C and as high ripple current as possible... and make sure that it physically fits inside your PSU too.

TheMobRules wrote on 2024-03-11, 07:42:

Yeah, you should be OK using low ESR caps for the smaller ones (I suspect the 100uF/16V and 220uF/25 are used on the output of the -5V/-12V lines, pretty much anything will work there)... as long as you avoid ultra-low ESR electrolytics (which are not even produced anymore) and polymers for the reasons mentioned above you should be safe.

Unfortunately I can't find any circuit diagrams for this Chieftec PSU series. There's no -5 V line in this PSU, but there is -12 V and I think the only Samxon RL 100 uF/16 V is on the output of the -12 V line (have to check it with the multimeter for sure) and the other two Samxon RLs 220 uF/25 V are connected to one of the smallest transistors (I'm just guessing that it's a transistor) in the middle of the main PCB (I can not see exactly what is this transistor-like three-pin element because of the heatsinks shapes) - maybe they're related to +5 V stand-by voltage.

P.S. Ok, I found one circuit diagram for similar model CFT-650-14CS PSU here: https://drive.google.com/file/d/1AvUjao7uFNPY … 8wLJ9UX1PM/view

These are the three questionable all-purpose Samxon RLs, that I wonder if there will be a problem to be replaced by low ESR/impedance caps:

TheMobRules wrote on 2024-03-11, 07:42:

For the low ESR caps (SC and GF in this case) just try to find replacements that match the ripple and impedance @ 100KHz from the datasheet in addition to capacitance/voltage. More ripple tolerance is OK, and it doesn't need to be a totally strict match with the impedance, just stay in the ballpark and you'll be fine, the design of these circuits usually allows for some leeway as long as you stay between certain minimum and maximum values.

In worst case I'll go with Samxon GFs. The original ones lasted almost a decade and a half, so they're not so bad and seems better than Teapo SC. But first I'll check those Samwha low ESR - there's no info which series on the store's site. I think the Panasonic and Nichicon caps might be fake because of their listed low price.

momaka wrote on 2024-03-11, 08:30:

Try sticking only with good Japanese brands like Rubycon, Panasonic, Nichicon, and United Chemicon. SamWha is -kind of- junky... […]
Show full quote

Try sticking only with good Japanese brands like Rubycon, Panasonic, Nichicon, and United Chemicon.
SamWha is -kind of- junky... about on par with Samxon GF: they'll probably last you a few good years in the PSU, if not more... but eventually, you will have to re-recap the PSU again. In contrast, quality Japanese caps will be a lifetime repair.
As for Elite... they are so-so too. I've seen them used a lot in LCD monitors, and depending on which series we are talking about, they can be anywhere from very decent to not very good. Also depends if they have been abused with heat. The ones that weren't do OK. But again, if better quality caps are available to you, I'd go with those. The price difference should be negligible.
As for Jun Fu... Junk Fu is putting it nicely. I'm not a fan of this brand.

Here are some series that should work with your PSU from the above Japanese brands:
Rubycon: YXJ, YXH, YXM, PX (general purpose series), ZLQ*, ZL*
Panasonic: FC, FK, FR*, FM*, FS*
Nichicon: PW, PS, PM, PJ, HE, HD, HW*, HV*
United Chemicon: LXZ, LXY, LXV, KY, KYB, KZE, KZH*, KZM*

* : I've used some of these in PSUs before, but their ESR may be a bit too low for some PSUs.

Just follow what TheMobRules mentioned about matching the replacements. Indeed most PSUs tend to be quite flexible in what they can take, so it's not critical to match ESR or ripple current exactly. +/- 30 to 50% for the ESR is fine. Ripple current - higher than the original would be better... but in a pinch, lower RC from a high-quality Japanese cap manufacturer will usually do fine too. And as far as capacity and voltage ratings go: anywhere you see 6.3V caps, you can safely use 10V caps and vice versa. For capacity, going a notch up or down is usually not a problem either... though it's preferable to go up if the right size is not offered - e.g. putting a 1200 uF cap in place of a 1000 uF cap. Actually, even 1.5x higher capacitance won't hurt (if anything, higher capacitance is better... within reasonable limits, of course.)

In regards to the big cap(s) inside the PSU: does it have 2x 200V caps or one (or more) 400V/420V/450V caps. The former is typically accompanied by a voltage-selector switch and means the PSU does not have an APFC circuit. The latter means your PSU does have APFC. This is important to note, because APFC tends to stress the primary caps a lot more than non- or PPFC PSUs. So if the primary cap(s) is/are not a Japanese brand from the ones mentioned above (or Hitachi), you may want to replace it too. Just note that this/these large 400V/420V/450V caps will be rather expensive. My general rule is: if the PSU will be seeing a lot of use at high load and if the original cap was only rated for 400V (and especially if it's not a Japanese brand), then it's better to replace it - preferably with a cap rated for 420V or 450V. The primary cap doesn't have to be low ESR... and you will see that you probably won't find it in the above series. For this one, it just needs to be rated for 105C and as high ripple current as possible... and make sure that it physically fits inside your PSU too.

Thank you very much for all the detailed information! I've just sent you a PM, you'll see why 😉

The PSU is with Active PFC and one big mains filter capacitor Nippon ChemiCon SMQ 390 uF/400 V/85 C. I can't find any suitable replacement for this one due to its dimensions (nearby heatsinks and some transformers/chokes will interfere if I try to install slightly higher or wider capacitor), but the original one seems to be healthy enough and from a respected brand.