Rebuilding a Seasonic SS-300ET

[jsog]

This supply has been in use since 2009, no problems. I'd read lately about this series using cheap capacitors. So I swapped it out, planning to replace the caps and maybe the fan.

Now, I'm not sure it's worth it. First:


Yes, that's a resistor and capacitor hanging by one leg. The IC is crooked, so probably the unattached leg should also be stuffed in with the chip but slipped out before soldering. Probably.

One largish cap of unknown brand, marked CE(M), UQ 85 deg C, 180 uF, 400V, 8306K. Thirteen OST capacitors, many in hard-to-reach places or glued down with that brown glue, or both:


RLX, LP, RLS series. No idea what to use for replacements.

Is it worth rebuilding this? Any recommendations for a better-quality supply? This system only draws about 80W in use, so a small one is fine.

[Th3_uN1Qu3]

Re: Rebuilding a Seasonic SS-300ET

That's a compensation network on that optocoupler there, i guess they wanted to install that but changed their mind on the way. Probably a slip on the production line.

As for the OST caps, they have datasheets on the website.

[jsog]

Re: Rebuilding a Seasonic SS-300ET

OST's web site is broken in places, but I think I found replacements. The ripple rating is really high on the larger OST caps, higher than Panasonic FM. Can you recommend replacements for these bigger ones (maybe poly?):

2200uF 16V RLX, 10x25, ESR 0.21, ripple 3000mA
2200uF 10V RLX, 10x20, ESR 0.21, ripple 3000mA
3300uF 10V RLX, 10x25, ESR 0.014, ripple 2780mA

[Behemot]

Re: Rebuilding a Seasonic SS-300ET

Don't worry, shitty caps are usually overrated, true is most PCB manufacturers realize that and make the circuits able to somehow work only a fragment of the specs (like bulged caps etc).

I usually dont even look at datasheets of this craps (you can't find them mostly anyway) and use Samxon RS and Chemi-Con KY caps just fine. RS were workign liek charm in my SS-500ET-F3. Pity I blast whole +5 V SB rail than, year after recap when swapping cables The input one was Panasonic IIRC.

[jsog]

Re: Rebuilding a Seasonic SS-300ET

Yes, the input one looks like it has the Matsushita "M" (in addition to the tolerance code M). Strange lower-case "t" vent, not the Panasonic swoop T. That one can stay.

The OST datasheets don't even show some of the sizes used in this supply. The 3300uf 10V, which is 10x25mm, appears to not exist anywhere. Badcaps.net has a 10x30 Samxon RS, though.

[Behemot]

Re: Rebuilding a Seasonic SS-300ET

Quite common are 10x35 or something like that, 4700 uF, Teapo I think. Don't know whether it actually has at least 3300 uF when it's brand new…

As for the dimensions, they may be custom order. Also Joe has this RS for 16 V (together with some small GF) custom made, Man Yue does not make them normally.

[PCBONEZ]

Re: Rebuilding a Seasonic SS-300ET

. The 3300uf 10V, which is 10x25mm, appears to not exist anywhere.

Any 10x25mm in the same series will have about the same specs.
From a 'real brand' it would be exactly the same.
ESR varies within a series with the physical size and shape of the cap, not uF or volts.
.
RS might not be good enough.
If you look at the rest of the RS series the specs given for the custom size are clearly bogus.
.

[Behemot]

Re: Rebuilding a Seasonic SS-300ET

Well yeah I didn't even know what Joe has on web, I know it's most likely quite inaccurate. Most important is they are low-ESR, that's all what I need to know.

Only problem I ever had was the Chieftec where probably whole compensation was made for craps, anything of better quality than the originals has lower ESR which means problem. Otherwise three years of experience using Samxon RS in pretty much every PSU which goes through my hands.

[jsog]

Re: Rebuilding a Seasonic SS-300ET

Is there any reason I shouldn't reconnect the loose RC lead? That strikes me as a manufacturing error. The bending of the capacitor leg makes it fit to pin 3 of that optoisolator, although I'd like to see another one to be sure.

The chip is a NEC 2561. The resistor in heatshrink is 3.3K, the capacitor 0.47uF, and pins 3 and 4 of the optoisolator are the output/phototransistor side. Filtering out high-frequency noise?

[Th3_uN1Qu3]

Re: Rebuilding a Seasonic SS-300ET

That is a compensation network. If the power supply does not squeal or anything (you don't have an oscilloscope don't you?), remove it. It may cause other problems if it's not the right compensation.

[seanc]

Re: Rebuilding a Seasonic SS-300ET

Can we get a full top down picture? I'm thinking it looks to be the same layout as my Seasonic S12-II & Antec EA380.

[Behemot]

Re: Rebuilding a Seasonic SS-300ET

Yeah it is, evolution of the original Tornado. This design is with us for some seven years now, pretty damn good one. From Tornado to S12, S12-II, S12-II Bronze and many OEMs including Seasonic's own OEMs (SS-x00ET).

But I don't remember any such a resistor with capacitor over optocoupler in my former SS-500ET-F3…

[jsog]

Re: Rebuilding a Seasonic SS-300ET

Full board, without the OST capacitors removed earlier today. Hanging cap/resistor is top center.


Hadn't noticed the "ATX400W" until now. Evidently a generic board.

[Th3_uN1Qu3]

Re: Rebuilding a Seasonic SS-300ET

I wouldn't call it generic. There are Corsair labels on the transformers and the layout isn't typical. And i'm quite sure someone DID test this at the factory and decided the RC combo isn't needed, maybe they got a batch of optos with wide tolerances, and some of them needed it, some didn't. The sloppy mounting of the opto is a good evidence of that.