Recapping my PSU (non PFC) & a little modification

[yanz]

Well I want to practice first before make any attempt to recap pricier PSU (Tt, Fortron, hec, etc...).

So I pick the cheap one, ATK (AIBO) 380W ATX PSU. I got it with the $40 case, the psu itself maybe cost $20. It has been powering my duron1300 rigs since a year ago, running folding@home 24/7.

The original look before modification, this unit is very silent when operate even outside the case:



Spec:



The original bulk caps (hey can somebody tell me what brand is it? Looks like planet Saturn's.. :P) :





The PCB trace (back). Notice the green wires, I made a switch (green wires <--> ground) so no mobo required to power on the psu:






I was searching for snap in type (bulk) caps from the shop/distributor for value => 470uF 200V. I have no clue what should i get. They give me the KMM chemicon caps. I don't know if it is suitable for my needs (high ripple, low ESR, long life). But the shop tells me that they are good for audio power supply. So, I take it. When in doubt, buy it! That's my motto... The price is almost $2 a piece. Wow!

Fortunately, after i check the data from chemicon website, these caps are the good ones.









From the data above I draw conclusion that what I should get are (in order): KMH, KMM, LXQ, LXM

I make a quick comparison between them:



KMM is really good compared to the higher spec LXQ. The endurance is 3000hrs though (@105C). That's should be enough.

The recapping isn't really difficult.




Notice the EMI filter. I don't know if installing an EMI filter will make any good for the non pfc psu. But I did it anyway, because I can... lol I have some PSU w/APFC that already have it.





Btw the original caps in secondary side are some Su'scon and Koshin.

Caps that I use for this project:

Brand & Series		Capacitance	Volt	Dimension	Pieces	Ripple Impedance/ESR
----------------------------------------------------------------------------------------
Panasonic FC		680uF		16V	8x20mm		2	995 	65	
Rubycon ZL		1500uF		16V	12.5x20mm	6	2360	21
Panasonic HFQ		2700uF		16V	16x25		1	2070	28
Chemicon KMM		680uF		200V	25.4x40		1	780		366

Some original caps under 100uF were replaced with some Panasonic KG, TE, MH.




The hard part is that I have to desoldered the wires (ground, 12V, 5V) first. That makes recapping a lot easier. In the end, all caps seat nicely, no need to bend the legs or any tricks...


.

[yanz]

Re: Recapping my PSU (non PFC) & a little modification

more pics uploaded...

[linuxguru]

Re: Recapping my PSU (non PFC) & a little modification

You don't really need to change the primary side caps - they rarely fail, except for one small cap, 22 uF or 47 uF near the auxiliary flyback transformer. Also, you've probably used a bunch of 16v caps where 6.3v or 10v would do, on +5vsb, +5v, -5v. You only need 6.3v caps on +3.3v. You can use either 16v or 25v caps on +12v and -12v. 1000uF/25v is sometimes very inexpensive and available easily, and usually has a higher ripple current rating than 1000uF/16v of the same series.

Other than that, the specs are fine - overkill, actually.

[linuxguru]

Re: Recapping my PSU (non PFC) & a little modification

BTW, the original PSU was probably no more than 200W, notwithstanding the 380W spec.

[kc8adu]

Re: Recapping my PSU (non PFC) & a little modification

looks like an allied.
they are often packed with ost and swcon/rulycon(rubycon fakes)

[Newbie2]

Re: Recapping my PSU (non PFC) & a little modification

I have seen those same Saturn main caps in an L&C LC-B450 E 450W power supply before.

Is the exterior of the cheap 380W 120MM fan power supply still the same?

Post an after photo of the exterior of the power supply if you can.

[Reina]

Re: Recapping my PSU (non PFC) & a little modification

Hi,

i modified the same model too, it is very nice build but has poor output capacitors and week shottky diodes. i changed that and build a better thermal-control for the fan too.

i got a nice silent low power supply (with maybe 250W)

greetings.

[linuxguru]

Re: Recapping my PSU (non PFC) & a little modification

Cool - it looks like the topology for the auxiliary (+5Vsb) flyback converter includes an optoisolator and does not have the Achilles heel (a small primary-side cap) typically found on these supplies. Does it have a Topswitch TOP221 or similar TO220 device as the primary switch on the auxiliary supply? The TOP22x provides excellent regulation and a simple topology, but less protection against mains spikes. An MOV on the input is highly recommended to protect the FET.

[linuxguru]

Re: Recapping my PSU (non PFC) & a little modification

BTW, if it's a TOPswitch, you need to stick with the recommended values of the capacitors on the secondary-side pi-filter for +5Vsb. IIRC, it's ~330uF or so - if you go much higher, it will alter the transient response and stability. Anything over 1000uF is probably too high.

[PeteS in CA]

Re: Recapping my PSU (non PFC) & a little modification

One curiosity to look for with TOPswitch has to do with the start-up function. If you turn off AC power to a P/S, there may be enough energy in the I/P lytics that the TOPswitch will try to start. It immediately shuts down again, but if you have a 'scope on the +5V Stby, set for 1 second/division, you'll see several pulses from start-up attempts.

[japlytic]

Re: Recapping my PSU (non PFC) & a little modification

The PCB has a lot of space on top, because there are a lot of SMD components underneath. Why didn't the manufacturers put provisions for extra electrolytics in large areas of unused circuit board space on the top?

[yanz]

Re: Recapping my PSU (non PFC) & a little modification

actually i wrote a long post but lost it because power outage..

@japlytic
maybe because it's cheap (~$17).. i found a bunch of LC PSUs in the same shop.

@Reina
Thanks! That's the same board as mine Can you describe more about the mod you did with your PSU? I want to see if I can do the same...


@linuxguru
Yup, overkill.. that's what I want it to be Imagine a bunch of those here (~20 of them) expected to be lasting for 5 years (no kidding), how can i rely that mission to the crappy taiwan caps?

Actually, at first attemp to recap months ago, I use some rubycom mbz 10v. But then I changed my mind & replace them with pannys hfq & fj 16v. The fj seems to be getting too hot while touching the toroid. So, while thinking that i should bend (desolder) the torroid a little bit to the heatsink direction (done), i said why don't I change all the caps to rubycon zl 16v? It clearly has higher ripple and lower esr than any of the hfq and fj (and elna rjj and rubies yxf) while has the same price. So be it Now the jungle of caps looks more homogen..

I have a bunch of those 1500uF 16V ZL. I run out of stock for the 1000uF RJJ, YXF, and 1500uF HFQ. No more supply of them from the distributor. All of them have 12.5mm diameter. he price for the ZL is ~20 cent($) per piece. However i'll try to be wiser for the next mod..

Btw sorry for my noob, can you explain where and what is the auxiliary?

BTW, if it's a TOPswitch, you need to stick with the recommended values of the capacitors on the secondary-side pi-filter for +5Vsb. IIRC, it's ~330uF or so - if you go much higher, it will alter the transient response and stability. Anything over 1000uF is probably too high.

How to know if that replacement for the caps need not to be over 330uF? is 680uF 16v okay? What is the "TOPswitch"?

@Newbie2
I dug some pics, and can only find this.. it's really just a simple box..

[Rainbow]

Re: Recapping my PSU (non PFC) & a little modification

I had a fan like that (the same "brand" but 8cm) and it died after a couple of months. So prepare to replace that too.

[Newbie2]

Re: Recapping my PSU (non PFC) & a little modification

I had a fan like that (the same "brand" but 8cm) and it died after a couple of months. So prepare to replace that too.

That's what happened to me too in a cheap L&C LC-B450 E 450W power supply after a few months. The 8MM (or 8CM) version is very silent but also very weak. Instead of the white sticker it had a blue sticker. The sleeve bearing doesn't last as long as a ball bearing, so the best replacement is a good 120MM (or 12CM) ball bearing fan that has good airflow.

The "saturn" brand is no good. I believe they also make the main caps for current L&C power supplies.

[linuxguru]

Re: Recapping my PSU (non PFC) & a little modification

> Btw sorry for my noob, can you explain where and what is the auxiliary?

The section of the PSU that supplies both +5Vsb as well as the Vcc for the controller IC. In this case, it is the circuitry around the small yellow transformer furthest away from the main (larger) transformer. It is usually 'on' all the time that the PSU is plugged in.

> How to know if that replacement for the caps need not to be over 330uF? is 680uF 16v okay?

Check the original values and try to stay within about +100% of the original capacitance. 680 should be OK.

> What is the "TOPswitch"?

It's a 3-terminal Power IC that includes a High-voltage Power FET as well as an SMPS controller circuit on the same die. It's usually in a TO-220 3-pin package, or an 8-pin DIP. It allows building a low-power (upto ~20W) flyback SMPS with very few components, and is commonly used as the switching device in the auxiliary power supply of ATX PSUs.

[PeteS in CA]

Re: Recapping my PSU (non PFC) & a little modification

tw sorry for my noob, can you explain where and what is the auxiliary?

With ATX forward, there is a section of the P/S that is always on (if AC is applied). This is called the "standby" or "auxilliary". It supplies power to the MB logic that enables or shuts down the main P/S converter.

TOPSwitch is a trademarked name for Power Integrations' IC, described above by linuxguru. STMicro was working on a functionally similar product back in 2000, but I don't know whether they ever marketed it.

[yanz]

Re: Recapping my PSU (non PFC) & a little modification

Thanks, that's the explanation I need.

I had a fan like that (the same "brand" but 8cm) and it died after a couple of months. So prepare to replace that too.

I'll search for 12mm panaflo fan.. they are reliable and quiet.. (@7V). Thanks for the info..

[Newbie2]

Re: Recapping my PSU (non PFC) & a little modification

DEER makes a power supply that looks to me identical. L&C, a DEER company, uses those blue "saturn" main caps, and also uses the generic "saturn" fans. DEER doesn't have them in 380W, but the closest they make are 350W and 400W. In one of those photos yanz posted, I saw half of the "P4 Support" warranty sticker, and it is commonly on DEER and L&C power supplies. I included yanz's picture with a red oval on the half of the warranty sticker. Have a look for yourself.

http://www.deer-group.com/switch-12cm.htm

[Newbie2]

Re: Recapping my PSU (non PFC) & a little modification

Here's for comparison:

[gonzo0815]

Re: Recapping my PSU (non PFC) & a little modification

@linuxguru
I have a few Seasonic SS400FS here, if an topswitch is an 3 pin to 220 switching ic including the fet, than i have some questions. As far as i see, all 4 SS400fs i own, have an bulging 470uF / 10V Fuhjyyu capacitor close to the auxiliary transformer on the secondary side. Now, as i didn`t found any datasheet for those 3 pin switcher, i used an 1500uF MCZ Rubycon. At the moment the PSU are running well on the test rig (K7s5A Pro, Duron 700@933@1.87Vcore) runing Prime95.
But you stated, above 1000uF ther could be problems. What kind of problems will ocure and are they critical? I messured the Vsb with a DVM and it is about 4.95V as usual.
Should i replace that 1500Uf MCZ? And if yes, should this be an low esr type again?

Is the input capacitor (i mean that low voltage capacitor on primary side, not the high volt bulk ones, probably the power supply for the switcher itself)) critical for the PSU, i.e would do the psu cause catastrophic failure if that cap will gone?

if you coild link an datasheet this would be very helpful to me.