Antec SL450P Smart Power Exploded!

[goodpsusearch]

Today I went at university storage department and I had there over 30 psus to check (and take whatever I liked). Among them there were 2 antec, clearly the best, theoretically at least...

The 2 antecs were identically same: SL450P Smart Power 450watt output.

The first one did not work at all, no output voltages or fan movement.

The second one when connected to AC with the psu on sorted with ground, it exploded with a loud sound and sparks coming from inside.

I got the first one home and opened it... Nothing seems to be bad. Crappy caps everywhere but noone bulged or leaked or exploded. Psu is brand new, has no dust in it... Maybe they got it dead on arrival.

I upload some photos to see for yourselves. Do you know possible failure reasons?

[weirdlookinguy]

Re: Antec SL450P Smart Power Exploded!

PSU has seem some use, not brand new. If you look carefully there's a very light coat of dust at various places, especially on the fan blades and the primary caps.

[Toasty]

Re: Antec SL450P Smart Power Exploded!

>>Do you know possible failure reasons?<<
Yes. Bad caps.

Where's the one in the thread title? I came to see death, carnage, and dismemberment...

[Toasty]

Re: Antec SL450P Smart Power Exploded!

Check for 5vsb power.

[goodpsusearch]

Re: Antec SL450P Smart Power Exploded!

weirdlookinguy you are absolutely right...

I think I found why its dead. See the MOV...

Also, are these traces of water in the backside of board?

I guess I have no choice but return it.

[Toasty]

Re: Antec SL450P Smart Power Exploded!

Not MOV, PTC current limiter. Probably shorted primary switchers or bad mains caps, or both.

Not water. Flux residue from solder process.

Toast

[momaka]

Re: Antec SL450P Smart Power Exploded!

Not MOV, PTC current limiter.

It's a NTC actually (resistance decreases with increased temperature).

If fuse is intact, replace the burned NTC with one from a junk PSU. Sometimes those NTCs burn out for no reason. Replacing them usualy makes the PSU work fine again after that. If I remember correctly, etnietering here had a similar problem with a cheap Logisys PSU.
If fuse is blown, don't bother with it (i.e. use for parts only).

[Toasty]

Re: Antec SL450P Smart Power Exploded!

Yup, NTC. Thinking of TV degauss again... DOH!

[etnietering]

Re: Antec SL450P Smart Power Exploded!

momaka is right, my 15 dollar logisys unit popped it's current inrush limiter. Mine didn't just blow a side out, it shattered the whole thing! I have it around here someplace....
Anyways, the rest of the PSU was fine, and it ran for more than a week after I replaced the CIL before the replacement PSU showed up. Replacing it with one from a junked PSU would be fine, and they don't seem to be in short supply for you!
Here's the thread about my logisys, and all the improvements I've made to it: https://www.badcaps.net/forum/showth...3&page=1&pp=20
I'll try to dig up the picture of my exploded CIL from that power supply

[etnietering]

Re: Antec SL450P Smart Power Exploded!

well, turns out I didn't get a picture of the blown CIL, but I did take pictures of the nicely toasted ATX12v -> EPS12v adapter...


and here is the adapter-ectomy I performed so that the computer would run again:

[goodpsusearch]

Re: Antec SL450P Smart Power Exploded!

The fuse was blown too. I took it to uni and with a guy in charge there we tried to make it work again. We put out the fuse, removed pfc to see if that was failed, but finally it did not work. A mosfet (I hope I name it right) was dead.

Sorry for bad english and terms.

[Toasty]

Re: Antec SL450P Smart Power Exploded!

Check those mains caps and replace -all- the Fuhjyyu caps while you're there. Mains cap going short/open will take fuse, surge limiter, and switcher(s) FET's. 3 this week.

[goodpsusearch]

Re: Antec SL450P Smart Power Exploded!

...both units are now used for spare parts by the university guy :P

[goodpsusearch]

Re: Antec SL450P Smart Power Exploded!

I had a long time ago those 2 antec psus, that tried to revive... The one was completely dead, we made some attempts with my friend, the tech guy that provides me all that stuff, but we had no luck and decided to use it for parts. The other, when connected to the mains, made sparks and a loud sound and the room's automatic switch went down. After that I was too scared to even touch that antec to take out its parts


6 months later I have 2 more antec smart power psus to play, that are identical to the previous ones.

I got the first yesterday and checked its fuse and ntc thermistor and found them ok. Then I checked its caps and found 1 of its 2 main 470uF caps to be completely dead. I replaced it temporarily with a 560uF cap measured 420uF and tried to connect it to mains. Again, sparks, a popping sound and my room went dark...

The psu's fuse and thermistor are still working..

I don't know what is the next thing I should check... if there is anything to do before quitting again..

[Krankshaft]

Re: Antec SL450P Smart Power Exploded!

How did you determine the cap was shot? Also there are two caps on the primary of passive PFC switching supplies active PFCs only have one.

With a major short like that probably either the bridge rectifier (one of the internal diodes) or the switching FET is shorted.

You can't just replace a component plug it in and cross your fingers without checking the surrounding circuitry for the cause of failure or you could easily blow the parts you replaced.

I find it odd that the fuse didn't blow unless you've got a real sensitive circuit breaker reacting faster than the fuse or the fuse is faulty.

[Scenic]

Re: Antec SL450P Smart Power Exploded!

Also there are two caps on the primary of passive PFC switching supplies active PFCs only have one.

not in antecs

my TruePower 550EPS also has 2 200V input caps with an active PFC.

seems like antec just piggybacked an active PFC PCB on top of the area where the primary caps are and connected it to where the rectifier on a non-PFC model would be. probably went with an active one as there wasn't enough space for a passive one... poor antec couldn't cut corners here as they usually do (fuhjyyu anyone?)

makes me wonder if those PSUs weren't designed for the european market in the first place (PSU's without any PFC (active or passive) are banned in the EU)

pics
https://www.badcaps.net/forum/showthread.php?t=9365

[goodpsusearch]

Re: Antec SL450P Smart Power Exploded!

How did you determine the cap was shot? Also there are two caps on the primary of passive PFC switching supplies active PFCs only have one.

I tested the cap with micro esr meter, and got esr:- (too high), capacitance: 0,1 when the other cap gave 420uF esr 0.12

You can see in the photos attached that there are 2 main caps and an active pfc circuit above them.

With a major short like that probably either the bridge rectifier (one of the internal diodes) or the switching FET is shorted.

Is there a way to check them with a multimeter and see if they are good or shorted?

I am not sure, but I think the sparks came from the area marked in red in the photo.

[momaka]

Re: Antec SL450P Smart Power Exploded!

Yes, you can check FETs and diodes with a multimeter.

To check a diode, measure the resistance across its terminals (or use diode check function), then reverse the probes and measure again. If you get a reading of a few Ohms or short circuit both ways, then the diode is shorted.

For FETs, it's the same as diodes - check with multimeter between Source and Drain and see if there are any shorts.

Keep in mind that if testing in-circuit, your readings may be inaccurate. For example, some PSUs have low-ohm resistors (I've seen as low as 4.7 Ohms) on some of the output rails. If you're testing an output schottky rectifier on a PSU like that, you will see this low-ohm reading between anode and cathode regardless of you measured it with your multimeter and you might conclude that the rectifier is shorted (when in reality, it might not be!)
Therefore when testing diodes and FETs in-circuit, always check what the rest of the circuit does.
*OR* if it's easier for you, just take the diode/FET out from the circuit and then check it.

Like Krankshaft suggested, first check the bridge rectifier, then move in on the rest of the circuit (FETs, protection diodes, etc.). If the PSU is tripping your circuit breaker, it's more likely that there is something shorted on the primary side.

[mur]

Re: Antec SL450P Smart Power Exploded!

I would check the APFC mosfet. I think it's quite a common failure in those psus. This is also what failed in my truepower 380w which has identical APFC board. I replaced it with another mosfet. When plugged in, +5vsb came on fine. When I shorted the ps-on with the ground the fuse immediately blew and replacement mosfet was shorted. Than i just replaced the wires that go to the PFC board with bridge rectifier. Psu worked fine. If you omit the PFC circuit like that, you would probably also need to increase primary caps capacitance.

[goodpsusearch]

Re: Antec SL450P Smart Power Exploded!

Success

I checked the fets and the bridge rectifier with my multimeter and found the apfc mosfet to be completely shorted!

The mosfet is a 2SK2996 and I got 3 more of these that all came from the pfc circuit of 3 antec smart power 450w psus (or what have remained of them).

Only 1 was found not shorted so I put that apfc on the psu I tried to repair and... the fan spins!

All voltages were found ok, so I am going to make a recap list soon.

The case of those psus is similar with that one:
https://www.badcaps.net/forum/showthread.php?t=2474

About the other antec I have, I don't think it is going to work if I remove the apfc and replace the pfc cables with a bridge rectifier, because there is also a red wire going from apfc to pin 7 of the pwm ic UC3844B that is the Vin of the chip.

I measured the red cable of my working antec and it was ~18V.

I don't want to mess with that stuff so I think it's a better idea to replace the shorted mosfet 2SK2996. From a quick search at rs site I found that:
http://gr.rsdelivers.com/product/stm...v/4857428.aspx
Do you think this is a suitable replacement?