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HX650 doesn't output 5V!


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I've just received my PSU back from RMA.

Got a brand new HX650 as replacement for a dead HX520, fine with that.


However, I just put it back in my system and was worrying about no hard drive powering up as system started :confused:

Thinking the dead PSU killed my hard drives, I've plugged another one, working for sure.

It won't power up either :confused:


However system starts fine.

Into the BIOS, I can check that all voltages are OK.

Fans attached to the 4-pin Molex cables start OK.

USB devices power up.


So what's wrong?


I've measured with my multimeter voltages on the 4-pin Molex.

12V is OK, but there is no 5V at all!


Faulty cables? Impossible, they were fine before. Tested with new ones aswell.


So I've taken voltages directly from the peripherals modular socket, and here is what I've found:

This must be understood as PSU fan facing up, socket holes from top to bottom, this way:



Based on the Molex cable wiring, here is what I should measure:

[?]   o--

[5V]  o--\                    -----o
         |-- 5V
[GND] o--/                    -----o
                                        Molex plug
[GND] o--\                    -----o
         |-- 12V
[12V] o--/                    -----o

But here are my results:


   |-- 0V       [b](-> Should be 5V!)[/b]

   |-- 12.10V   [b](-> OK)[/b]

o   |    
   |-- 3.40V
o   |



What's wrong with this PSU?

Have I received a faulty unit, as it seems?


Besides, I won't pay 25 euro more to send this unit back to Netherlands again! Only because I received a faulty unit.


Thanks for your help.



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After rereading what you've written, I think I misread what you've posted. Sorry about that. Have you checked within your BIOS to see if it is detecting your hard drives? In all likelyhood it won't see them in which case you'll need to contact Corsair to see about getting some help in regards to shipping costs on a second RMA. Usually on a second RMA they'll pay both ways.
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As you said, obviously, the BIOS won't detect any hard drive as they are off!


I see you've edited your post... You've previously written:

I see five voltages measured off of four wires. This would lead me to suspect that you don't know how to check voltages off of a molex.

Just to make things clear... 5V should be there in the first figure (see my first post), but it isn't.

So I've checked what is at the end of each plug...



BTW, I've used ATX PSU as standalone DC power sources, without any motherboard connected. Even with no motherboard at the end of the 24-pin plug, the PSU should output 5V and 12V at the end of Molex cables.



I've contacted Corsair via the contact form, because I don't want to initiate a new RMA, without the option of an advance RMA and return postage paid by Corsair.

Still no news from them. :confused:


When I asked for a RMA for the former HX520, I've got my RMA number within the hour... :roll:

I expected having some answers from Corsair Tech Support on this board :(:

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Yep, after rereading your post I realized I'd lost track of which symptoms went to which post on which forum. Should have reread it before writing anything. Something's definitely wired wrong internally. Reviewing your diagrams from top to bottom, assuming the chamfered corners are correct and looking into the end of a molex or peripherals socket: First should show 12volts with the red multimeter plug touching the top lead in your diagram and the black lead touching either of the two middle ground wires (that's not what you're seeing); Second diagram should be reading 12volts, not 3.4volts; Third diagram, the 8.7 volts, is wrong to, normally jumping, outermost lead to outermost lead, from the +12volt lead to the +5volt lead with a multimeter will result in you seeing around negative 6.65volts (approximately -7volts, basically 5-12); Fourth Diagram should be reading 5volts when the red lead of the multimeter is touching the bottom lead in your diagram and the black lead is touching either of the two center grounds. In diagram form, following your corner chamfering scheme, looking into the end of the molex connector, a molex looks like this:


o---\-- +12v



o---/-- +5v

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Definitely! :roll:

That's what I was trying to demonstrate.

To sum up, in the right way, on the Molex:


o---\-- +5v •



o---/-- +12v


•= There is nothing at this end.


BTW, I've edited my first post to make things clearer (and correct typo mistakes). It wasn't well arranged so you misundertood the way I was disclosing the issue, and I also lead myself into the wall :(: Sorry about that.

There is no 3.4V on the Molex cable obviously! But on the peripheral socket on the PSU. But this is normal since SATA power needs 3.3V also. :):

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If your looking into the end of the molex, your drawing has the +12v and the +5v flipped from the way it actually is:




Your reedit does make it much clearer. In my reedited post above, fixing my missunderstanding and blended symptoms issue, the description of what you should be seeing and what you're actually seeing still stands. There's no way around it, that supply is definitely wired wrong internally.

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Yes it's flipped, but my drawing shows the way it is on the PSU socket, PSU fan facing up, so Molex pin-4 on top ;):

I conducted new tests, just to be sure, with another motherboard, and also with PSU standing alone with the paper clip trick.


This PSU has no 5V output on modular peripheral sockets.

5V is present on the 24-pin motherboard socket however.


Is there anyone at Corsair interested in fixing my issue :confused:

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As I've predicted, and despite I've asked for return postage paid and advance RMA, I've received a standard RMA approbation! :(:

Case number is 2459543.

No, no, I won't send back to Corsair this faulty unit at my own expense!

Please help regarding this!

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