Mike_ wrote on 2026-04-28, 05:52:

Hmm, would you think it'd be worth the effort to recap that Enermax, even though output seems to be fine or just wait and see? I'd actually like to have that in working condition as it's a pretty nice PSU otherwise, so it would be a lot more likely to see actual use than the Fortron.

What is worth is up to you, but I wouldn't trust those CEC caps holding up at all.

How did you measure the voltages, because just your basic "multimeter voltage" won't show you how the caps are working. You need to look at ripple and how "dirty" the voltages are and you need oscilloscope for that.

Example from real life: I just replaced caps on a 1980s 286 PSU. At first everything seemed to work just fine, but when I brought the system inside from workshop, the systems soon became very unstable and LCD screen in front of the case went haywire. I also smelled bad caps. Caps most likely started to puke their insides out when I started to use the system for longer periods of time and re-enwrgized them.

And guess what? Based on multimeter readings the voltages were still fine and completely in spec. As a matter of fact, even the capacitance of those leaked caps was in spec, only ESR was extremely high, like 5-8ohms for all the caps. Your basic voltage measurement doesn't necessarily show if something is already wrong. You notice it when your system starts behaving badly. Or smelling bad.

Ehh, it looks like there's lots of that yellow goo and even a couple of daughterboards with a bunch of small caps in them... If it's just a so-so PSU, I'd probably prefer not to spend the time for it.

It is up to you, but I wouldn't worry about the goo. It is often so brittle that you can just easily wiggle the cap off. And if not, you can cut it easily with exacto knife. It is not a problem or a hurdle.

And like I said before, just change the voltage rail filtering caps. Those small caps in the regulation and protection circuits are 99% chance just fine and stay that way for years. I personally change them for the most part, because with desoldering gun changing these caps is extremely fast if you have mapped them beforehand and you have the replacements at hand. I do it basically because it is not a significant effort at that point, not because I'm that much worried about those caps.

Okay one last question then before I decide to buy. I found this cheap FSP Fortron that has pretty good 5V and 3.3V, but it says that it's an Active PFC one. Do you think it could work or should I ignore any active PFC PSU entirely?

Also another silly question, how do you find out if a PSU is non-active PFC? I wouldn't have guessed this one was an active one if it wasn't for this huge sticker on it lmao. I know good rule for me is to look for PSUs with beefy 3V and 5V but some modern ones have them good too and yet they are not recommended for retro hardware.

Visual inspection of my whining ATX-400PNF PSU revealed one bulging 3300uf 10V Teapo cap. There is another 3300uf 10V and two 2200uf 16V Teapo caps right next to it, that I will also be replacing, just in case.

Caesum wrote on 2026-04-28, 21:00:

Okay one last question then before I decide to buy. I found this cheap FSP Fortron that has pretty good 5V and 3.3V, but it says that it's an Active PFC one. Do you think it could work or should I ignore any active PFC PSU entirely?

Also another silly question, how do you find out if a PSU is non-active PFC? I wouldn't have guessed this one was an active one if it wasn't for this huge sticker on it lmao. I know good rule for me is to look for PSUs with beefy 3V and 5V but some modern ones have them good too and yet they are not recommended for retro hardware.

https://www.elektroda.pl/rtvforum/topic1329491.html
And the following topics

PSUs with APFC emerged in response to the significantly increased power demands of the AM2/S775 era and graphics cards such as the 8800 GTX.
As a result, they are more complex and were used in more demanding conditions.
Whilst a unit without an APFC has most likely been sitting on a shelf for the last 15 years, one with an APFC has most likely been in operation somewhere in an office for the entire 20 years since its release.

appiah4 wrote on 2026-04-28, 23:07:

Visual inspection of my whining ATX-400PNF PSU revealed one bulging 3300uf 10V Teapo cap. There is another 3300uf 10V and two 2200uf 16V Teapo caps right next to it, that I will also be replacing, just in case.

Yeah, begone with them! PSUs are packed and hot, no happy life for a cap. And then the age on top of it.

CharlieFoxtrot wrote on 2026-04-28, 14:08:

What is worth is up to you, but I wouldn't trust those CEC caps holding up at all. […]
Show full quote

What is worth is up to you, but I wouldn't trust those CEC caps holding up at all.

How did you measure the voltages, because just your basic "multimeter voltage" won't show you how the caps are working. You need to look at ripple and how "dirty" the voltages are and you need oscilloscope for that.

Example from real life: I just replaced caps on a 1980s 286 PSU. At first everything seemed to work just fine, but when I brought the system inside from workshop, the systems soon became very unstable and LCD screen in front of the case went haywire. I also smelled bad caps. Caps most likely started to puke their insides out when I started to use the system for longer periods of time and re-enwrgized them.

And guess what? Based on multimeter readings the voltages were still fine and completely in spec. As a matter of fact, even the capacitance of those leaked caps was in spec, only ESR was extremely high, like 5-8ohms for all the caps. Your basic voltage measurement doesn't necessarily show if something is already wrong. You notice it when your system starts behaving badly. Or smelling bad.

I know, I even included a picture of oscilloscope screen in previous page...

Guys, I checked AKYGA site again for their PSU specifications and... It seems they are actually making Passive PFC units too. Look at this power supply:
https://www.akyga.com/products/3-power-supply … 1-420-420w.html

That's the PSU I was thinking about buying at the start of the topic before everyone suggested not trying this brand (I still won't buy it, I was just curious). Frankly I am surprised as I thought nobody makes passive PFC units anymore. Although they say it should be used with "current and next generation of platforms". Akyga is a Polish brand if anyone wonders.

On second thought, I guess I could recap that Fortron PSU.

I happen to have 3300µF 6.3V chemi-con KY series caps around that have been left unused, I bought them several years ago for recapping a motherboard but ended up not using them. So could I use them for replacing those 10V 3300µF caps? It sounds like it should be fine, as those caps must be for 5V rail. Or is there any reason why this would be a problem?

Mike_ wrote on Yesterday, 19:18:

On second thought, I guess I could recap that Fortron PSU.

I happen to have 3300µF 6.3V chemi-con KY series caps around that have been left unused, I bought them several years ago for recapping a motherboard but ended up not using them. So could I use them for replacing those 10V 3300µF caps? It sounds like it should be fine, as those caps must be for 5V rail. Or is there any reason why this would be a problem?

https://theswissbay.ch/pdf/Datasheets/ATX12V_ … _public_br2.pdf
page 29
Strictly speaking, of course not.

On the other hand, given that the voltage is 7V instead of 5V across the entire PC, the failure of two capacitors in the power supply unit is a minor issue.
In terms of ESR and ripple current, they’re perfectly fine.
https://chemi-con.com/wp-content/uploads/2021 … 5/KY-Series.pdf
https://nishioka.com/misc/teapo-sc.pdf
As for their diameter, it will be difficult to fit them into their mounting places on the circuit board.

shevalier wrote on Today, 06:07:

https://theswissbay.ch/pdf/Datasheets/ATX12V_ … _public_br2.pdf page 29 Strictly speaking, of course not. […]
Show full quote

https://theswissbay.ch/pdf/Datasheets/ATX12V_ … _public_br2.pdf
page 29
Strictly speaking, of course not.

On the other hand, given that the voltage is 7V instead of 5V across the entire PC, the failure of two capacitors in the power supply unit is a minor issue.
In terms of ESR and ripple current, they’re perfectly fine.
https://chemi-con.com/wp-content/uploads/2021 … 5/KY-Series.pdf
https://nishioka.com/misc/teapo-sc.pdf
As for their diameter, it will be difficult to fit them into their mounting places on the circuit board.

Yes, I'd also say that if the voltage ever gets up to 7V, there are worse problems... 😁

Anyways, that datasheet lists diameter of these caps at 12,5mm... that's curious...

Mike_ wrote on Today, 07:18:

Anyways, that datasheet lists diameter of these caps at 12,5mm... that's curious...

The attachment chemicon_KY.jpg is no longer available

Capxon LZ has become widely available in shops in my country.
This has been the case since the 2000s.
Not Lelon, Tiapo or Jamicon.
So, 99% of these are fakes that have absolutely nothing to do with Capxon.
The only way to tell is by measuring them with a ruler and comparing them to the datasheet.
See the image.
3300μF*10V – doesn’t exist in reality
3300μF*6.3V – genuine
4700μF*16V – doesn’t exist.
There are also 3300μF*6.3V ones on sale that are 5–10mm shorter, but these will swell up after a year just from sitting in the packet.

For reference, Capxon is now part of Tiapo and is used, for example, in Apple’s original chargers.

Where did you say you bought your Chemiсon? 😀

shevalier wrote on Today, 07:47:

Capxon LZ has become widely available in shops in my country. This has been the case since the 2000s. Not Lelon, Tiapo or Jamico […]
Show full quote

Capxon LZ has become widely available in shops in my country.
This has been the case since the 2000s.
Not Lelon, Tiapo or Jamicon.
So, 99% of these are fakes that have absolutely nothing to do with Capxon.
The only way to tell is by measuring them with a ruler and comparing them to the datasheet.
See the image.
3300μF*10V – doesn’t exist in reality
3300μF*6.3V – genuine
4700μF*16V – doesn’t exist.
There are also 3300μF*6.3V ones on sale that are 5–10mm shorter, but these will swell up after a year just from sitting in the packet.

For reference, Capxon is now part of Tiapo and is used, for example, in Apple’s original chargers.

Where did you say you bought your Chemiсon? 😀

It was some smaller online shop in 2010s. And yeah, I had the exact same thought. 😁

I bought around 400 caps today. Low ESR Samyoung and Samwha mostly for 1000uf and above, some Koshin for 470uf and below. Panasonic/Rubycon/Nichicon are just too expensive and difficult to obtain for me, I had no issue with these brands so far..