12v rail dead, Q-Tec 550w

[Rub87]

Hi,

This evening I was chatting and making tasks for school when suddenly a reboot took place, when the bios screen appeared it was full of crap so I tought my new moddable x800 pro vivo could RIP, but when I look @ it, no external damage was visible, but I cleary smelled something had burned..

The smell came from my psu, just out of warranty :/

If I turn on pc, prommy starts cooling down, and when measuring with MM, 12v rail slowly drops down.. I shut the pc down @ 6v..

The last days I experienced higher cpu temps and sudden reboots and I wondered why the prommy fans ware spinning so slow..

I opened it up, nothing seems burned to me. I've took some hi-res pics.

Who knows were to start searching? 5v and 3.3v are fine!

If we need some more pics, just ask away!!

Greetz and thank in advance!!

[stealthbomber]

I use to have that PSU, ran 24/7 at full load no problems but once every few months it would give out this burning smell, I replaced the 80mm fans with more powerful ones to lower the PSU temps, I believe the PSU was pretty much running very near its output limit on my setup.

Its closer to a 350W PSU than a 550W one, I'd replace the unit ASAP.

[Jamo]

OMG, get rid asap, i had a qtec 550w that 'exploded' - sparks flew out the back and tripped the fusebox on the house, fortunately it didnt take any hardware with it and no other damage was done, i'm never going back to qtec in my life - i've heard of many such incidents i dont know how the hell they pass safety inspections at all, if they even have them, it wouldnt suprise me if they just stick the pass stickers on in the factory without even being inspected - THESE THINGS ARE A SERIOUS DANGER! sorry i'm so irrate, its just a good job i was on my pc at the time, if not it could have burnt my bloody house down

[Rub87]

I use to have that PSU, ran 24/7 at full load no problems but once every few months it would give out this burning smell, I replaced the 80mm fans with more powerful ones to lower the PSU temps, I believe the PSU was pretty much running very near its output limit on my setup.

Its closer to a 350W PSU than a 550W one, I'd replace the unit ASAP.

Yeah, but 12v rail is dead :/

I'll search for antec or so...

Or wich other supllie do you guys recommend price/quality..

I'm planning to put a 148w on my x800...

[persivore]

Its probably one of the regulating MOSFETs which has died, or the inductor/transformer associated with the 12v line. Are there any signes of any damage to any of the MOSFETs?

[Butcher_]

Not worth fixing really. It's a low quality piece of crap PSU, you might as well just replace it.

[Rub87]

Nope, I don't see much damage, maybe on the second pic?But I think its glue and not a "bulb" on the mosfet..

Wich psu should I buy? Are Tagan supplies ok?

Ok, Then I'll buy a new and try to fix this as backup or for normal usage in my sisters pc ..? Do you know wich the 12v mosfets are?

12v isn't completely dead, when you trun pc on, I've around 10v, and then it drops and drop until prommy doesn't get enough voltage anymore...

[jimborae]

Ditch that psu now, they're are awful, well know for blowing up in a big way. Get yourself a PCP&C or OCZ Powerstream, very powerful & have a long warranties.

[Jamo]

yeah i run a tagan 480w, absolutley fine

well after my experience as well as reading of numerous other horror stories i wouldnt use it again, but its up to you if you want to risk it in your sisters pc

[Rub87]

Lol, 12v line isn't even regulated..

Check pic, I think this is how the 12v rail works,

Transfo --> 2 diodes --> output..?

Prolly one of the diodes or both ed up...

Maybe I'll just use it to power a pelt because It's real crap

[Rub87]

wHOOPPS

[persivore]

Lol, 12v line isn't even regulated..

Check pic, I think this is how the 12v rail works,

Transfo --> 2 diodes --> output..?

Prolly one of the diodes or both ed up...

Maybe I'll just use it to power a pelt because It's real crap

I think most PC PSU's use a regulator on the primary side of the transformer to control the output voltage.
If you are still getting a voltage on the 12v line, and it decreases, the problem might be a capacitor in the 12v regulator somewhere. I'm not very familiar with the exact operation of PC power supplies, and switched-mode power supplies can be very difficult to trouble-shoot/repair.

[Rub87]

I just bench tested it and seems to work ok, but I don't trust it, it costs plenty of time to reInstall it and why did the 12v line drop out? As I was experiencing instability for since a few days I'll buy a new one.. tagan 480w, ocz is kind'a expensive or am I seeing this wrong?

If you use a regulater on the primary side It isn't possible to regulate te rails separatly..

[jimborae]

Yeah OCZ is expensive but a psu isn't some thing I'd scrimp on as a good one will last years.

[Rub87]

Ordered OCZ 520w psu...

Atm the q-tec is revived..

Just modded my X800, 148w pelt and ramsinks installed...

Overdrive say's gpu temp is @ -5°C so tat's not bad .. I forgot to include me thermal probe in the isulation so I'll have to do it with soft readings..

12v is atm with pelt @ 11.50v, but I haven't run 3d tests so let's hope this thing pull it until my ocz arrives..