Corsair HX 450W shuts itself down after a while

[Paar]

Hi. I have bought used Corasir HX 450W power supply and have an annoying problem. I have a PC case with PSU situated on the top of it. Whenever I install this PSU in it and close the cover the computer shuts down after a while. If I let the case open everything is fine. I'm using mATX AM3 motherboard with integrated graphics and am cooling the CPU with big Scythe cooler. With it the CPU idles at circa 40°C/104°F.

I tried two different PSUs and none of them shows this symptom. The integrated GPU (in the northbridge) gets pretty hot but I'm sure it's not hot enough to overheat the PSU. When I put my hand on the vent side of the PSU I can feel warm air but nothing dramatic. I presume there is something broken inside but I have no idea where to look. Will somebody help me? I have some skill with soldering iron.

I have attached some photos of the internals of the PSU. Thanks in advance!

[stj]

Re: Corsair HX 450W shuts itself down after a while

i would solder a few wires onto the psu - ground, 5v-standby, and one of the main voltages.
then hook them to a meter and see which is dropping when it dies.

go from there.
because you need to narrow it down.

btw, did you inspect the back of the board for cracked soldering?

[Paar]

Re: Corsair HX 450W shuts itself down after a while

Well I have checked the underside of the board and it looks pristine. Some flux residue but that's that. About testing the voltage rails - you mean I should check both of them (+5V STB and e.g. +12V) with two multimeters and see which rail gets shut down first, that means first which hits 0V?

I've tried the PSU with another AM3 motherboard and it's the same. I have even tried to use it in my Pentium II machine which is primarily dependant on +5V rail and no shutdown occured. The insides got warm as the CPU hit 40°C and I have Geforce 256 and Voodoo 2 in there, both which are rather on the warm side of cards.

[stj]

Re: Corsair HX 450W shuts itself down after a while

i would not expect the standby to go down if the main fails,
but the other way it would because the main psu chips are usually powered from the standby supply.

to simplify it - just meter the standby voltage

[ChaosLegionnaire]

Re: Corsair HX 450W shuts itself down after a while

whats the voltage printed on the rubycon primary cap? 400v or 420v? cant see from the pics. i wanna bet its the apfc section that focked up and overvolted the primary cap and now the psu is wonky because the primary cap may be partly damaged from apfc overvoltage, so it shuts down during high 12v load.

[Paar]

Re: Corsair HX 450W shuts itself down after a while

The voltage is 400V, as seen on the attached photo. Would this problem be affected by case temperature? It seems that higher temperature speeds up the shut down. I have capacitor tester if that helps, I can desolder it and measure it. However it will show me only capacitance and ESR value.

[momaka]

Re: Corsair HX 450W shuts itself down after a while

Probably silly to ask this, as I'm sure you've checked, but does the PSU fan run when the PSU is upside down? If yes, does the fan appear to spin freely regardless of which orientation you have the PSU in (check by spinning the fan by hand and seeing how long it takes to stop - it should gradually slow down with a "wobble" before it stops and not slow down and stop quickly.)

Can you also post some pictures of the PSU's PCB solder side? Seasonic (the OEM that built this PSU) has fairly decent soldering, but still worth a check. Also check both the solder joints and the cable connections on the modular PCB.

[Paar]

Re: Corsair HX 450W shuts itself down after a while

Yeah I have checked the solder side of the PCB and everything looks fine. I'm attaching a photo so you can see.

The fan itself spins freely when upside down so that won't be a problem. There must be something else. The seller I have bought the PSU from has another one (650W variant) and when he puts it in a case so the fan is facing the inside, it shuts down too. He contacted Corsair support hoping that they would give us some advice.

It's just weird that nobody noticed such a problem with this series of PSUs. Probably showed up after some years of use.

[stj]

Re: Corsair HX 450W shuts itself down after a while

you have a cracked solder joint on the main transformer
given that they pull on the solder when upside-down, re-solder all of them.

[Paar]

Re: Corsair HX 450W shuts itself down after a while

Do you see the crack on the picture? Because I have disassembled the whole PSU, inspected the bottom side with magnifying glass and couldn't find any crack.

[stj]

Re: Corsair HX 450W shuts itself down after a while

yes, i see it - pin on the lower left in the photo is pulling out of the solder.
trust me - i see things like that long before most other people because i'v seen it so many times.

[Paar]

Re: Corsair HX 450W shuts itself down after a while

To clarify - are you talking about pins that are circled out, specifically the one with the orange arrow? I cannot see anything there but I'll do as you say and resolder them all, just to be sure.

[stj]

Re: Corsair HX 450W shuts itself down after a while

yes, that one.

[CapLeaker]

Re: Corsair HX 450W shuts itself down after a while

i'd heat certain things up inside and see what makes it quit.

[Quaddro]

Re: Corsair HX 450W shuts itself down after a while

well, based of my experience, if it works but after a while shutdown (not restart), mostly mean a component(s) is overheated.
Mostly due to overheated ic.

try to replace your 5vsb generator ic.

[Paar]

Re: Corsair HX 450W shuts itself down after a while

I've tried to open the PSU right after a shutdown and (carefully) placed my finger on every component I could reach. The only thing that produced any kind of warmth was the transformer and even it wasn't so hot it would bother me.

I have resoldered the pins of both transformers. Currently I don't have a PC I could test it on but I'll do it as soon as it'll be possible.

[momaka]

Re: Corsair HX 450W shuts itself down after a while

well, based of my experience, if it works but after a while shutdown (not restart), mostly mean a component(s) is overheated.

Yes, that might indeed be the case here, since the cooling can vary inside the PSU based on orientation, even if O/P says everything inside the PSU feels cool to the touch.

With that said, we shouldn't jump to the conclusion that it's an IC that is failing, especially the 5VSB IC. IME, ICs rarely fail, unless the PSU was designed poorly... which this one isn't really.

I suggest proceeding next with the tests that sjt suggested in post #4:
https://www.badcaps.net/forum/showpo...37&postcount=4
That is, see if the 5VSB goes out when the PSU shuts down. If the 5VSB circuit goes out, then so will the whole PSU. But if 5VSB is working OK all the time, then the problem is more likely on the main PS somewhere.

I've tried to open the PSU right after a shutdown and (carefully) placed my finger on every component I could reach. The only thing that produced any kind of warmth was the transformer and even it wasn't so hot it would bother me.

Interesting.

I expect the heatsinks should be the hottest parts in a PSU (and they usually are, at least from various PSUs I've tested.) The transformer should not be the hottest part by any means.

Perhaps try power-cycling the PSU and running it on again and again a few times until you can get it a bit hotter. Then see if anything changes inside, in terms of temperature.

[rayfloyd170]

Re: Corsair HX 450W shuts itself down after a while

To clarify - are you talking about pins that are circled out, specifically the one with the orange arrow? I cannot see anything there but I'll do as you say and resolder them all, just to be sure.

did you solve this problem by re-soldering the TX terminals?

[sam_sam_sam]

Re: Corsair HX 450W shuts itself down after a while

Do you see the crack on the picture? Because I have disassembled the whole PSU, inspected the bottom side with magnifying glass and couldn't find any crack.

What I see is several soldering joints that a lot of flux around the bottom of the joints or on top of the joints but I would also recommend that you put your soldering iron on the soldering joints on the switching power transformer as well you do not always see cracks on the outside of the joints sometimes it is component leads that the cracks appears but are to see