Corsair RM1000e - Help identify 5VSB Zener diode

[прямо]

Also worth to check the 5VSB feed back as well just to make sure nothing is wrong with it. Next to its output caps there should be a TL431 and a voltage divider resistor network that set its 2.5V reference voltage, which then get feed back to the TNY chip through an optocoupler.

If one of that voltage divider resistor network fails (very rarely happens), or if the TL431 itself fails, or the optocoupler fails (happens quite often), then the TNY chip will not be able to regulate 5VSB to the correct 5V voltage.

[hobostove]

I found a shorted transistor on the hot side with a thermal cam. Replaced it and 5VSB started up. Now I can see that I'm missing 12v1, and 12v2 is at 11V. 3.3V is fine. Time for more troubleshooting!

[hobostove]

Nvm, I have 12v1 and 12v2, tester connector was a little loose. However, they're only 10.8V. And after 10-15 seconds I can hear a relay click and the supply shuts down.

[hobostove]

Adding some photos here

[прямо]

Nvm, I have 12v1 and 12v2, tester connector was a little loose. However, they're only 10.8V. And after 10-15 seconds I can hear a relay click and the supply shuts down.

That's the protection mode kicking in, because 10.8V for 12V rails is an under voltage condition.

[Per Hansson]

It might not work without a load: connect something you don't care about, some old hard drives for example or a couple 12v car light bulbs to 12v and 5v outputs.

[CapLeaker]

That's the protection mode kicking in, because 10.8V for 12V rails is an under voltage condition.

Would be the slowest acting “protection mode” in the world. I haven't seen any protection mode that is that slow. I wonder what kind of voltages the op gets on the main filter cap?
I think the supervisor is a WT7527rt. It shuts the PSU down less than a half of a second.

[прямо]

Would be the slowest acting “protection mode” in the world. I haven't seen any protection mode that is that slow. I wonder what kind of voltages the op gets on the main filter cap?
I think the supervisor is a WT7527rt. It shuts the PSU down less than a half of a second.

Don't need to be sarcastic. Just tell me that I'm wrong, I can accept. I'm an adult, not a 5 year old kid.

[CapLeaker]

Don't need to be sarcastic. Just tell me that I'm wrong, I can accept. I'm an adult, not a 5 year old kid.

Not sarcastic at all. Just didn't make any sense! All you needed to do is to look for a detailed review of this PSU.

Here (page 3 is where the goodies are): https://hwbusters.com/psus/corsair-r...-psu-review/3/

Pull the data sheet of the Supervisor IC: https://www.techpowerup.com/articles...ges/WT7527.pdf

Read it, and it gives you all kinds of information on how it works and how to disable it. Now all major chips are listed in that review and thus you can pull up all the data sheets too! Carry on! 😉

[hobostove]

It might not work without a load: connect something you don't care about, some old hard drives for example or a couple 12v car light bulbs to 12v and 5v outputs.

I attached a load (3 old 3.5" drives), and now it's shutting down immediately and staying dead until it's left unplugged for a few minutes.

That's the protection mode kicking in, because 10.8V for 12V rails is an under voltage condition.

So definitely seems like protection mode kicking in. Maybe without a load 10.8V was just near the threshold of an undervolt condition, and with the load it droops into a definite protect.

Datasheet seems to agree.

Would be the slowest acting “protection mode” in the world. I haven't seen any protection mode that is that slow. I wonder what kind of voltages the op gets on the main filter cap?
I think the supervisor is a WT7527rt. It shuts the PSU down less than a half of a second.

I'm seeing 167V on the main cap. 120V mains here.

So 12V is low and it's shutting down. Where to go from here?

[CapLeaker]

Does your PFC work? At 167VDC at the main filter cap doesn't seem to be the case.
If you want to know if the supervisor IC WT7527 is shutting things down, measure the FPOB pin. If it latches high, the protection is on.

[hobostove]

10.2V then it shuts down

12V


5V


3.3V

[hobostove]

Does your PFC work? At 167VDC at the main filter cap doesn't seem to be the case.
If you want to know if the supervisor IC WT7527 is shutting things down, measure the FPOB pin. If it latches high, the protection is on.

FPOB is high @ 5V. Datasheet says it's an open drain. Shouldn't it go low if the protection is tripped?

[CapLeaker]

From what I see, I would expect the supervisor to shut the primary down.
Follow the trace from the FPOB pin. You'll end up on an optoisolator. Measure each of the 2 pins on the optoisolator on the secondary side against secondary GND. If both pins are at 5V the little led built inside the opto cannot light up, shutting the primary side down.
You can however disable that supervisor IC and force the PSU to stay on by grounding out the FPOB pin.
What's the VDC on the main filter capacitor when you plug the PSU in and turn it on? If you get only 167VDC your Power Factor Correction circuit isn't working in the primary. You should have something around to 380VDC. If you don't get that voltage on the main filter capacitor, no wonder the supervisor IC is shutting things down. No PFC means there will be no high power on the secondary.

[hobostove]

Both led pins of that optocoupler are indeed high. I think I follow now. If the supervisor IC is happy, it'll open a ground path for that led. If it's unhappy, it'll disconnect itself and the gnd side of the LED is normally pulled up somewhere.

I get 167V on the main cap, so next step is try to work out what's wrong with the PFC I suppose.

Going back a bit, before I got 5VSB to come up, I had to solve a short. Looking at it now, it was a transistor headed into the little PFC daughterboard. Probably more than coincidence. I'm looking at that area now.

[hobostove]

The transistor that was shorted was Q3 on this typical application schematic for the PFC IC (CM6500UN). I replaced it last week and the short is gone. Maybe the PFC chip is dead?

Worth noting the schematic here shows one mosfet, this psu has two. Also, I'm missing the 10ohm resistor and diode between the transistors and the mosfet gate. I do have the 10ohm leading back to PFC OUT though.

https://www.kediman.com/attaches/2017/04/906-vempt0.pdf

[hobostove]

PFC OUT signal looks like this on the scope, pretty much nothing

[CapLeaker]

Yeah… no. Your PFC isn't working. You need to fix that first. When the MOSFET shorted all 3 pins, it dumped full power to the gate drive circuit all the way back to the PFC IC. You have to inspect ever single part. Obviously your PFC IC doesn't do anything… depending where you got your parts from could be fake or fluke DOA. Look at the data sheet of the PFC control IC and compare your measurements on all pins. Could be the PFC IC is in under voltage lock out or VCC is missing, a component near by open, a busted trace or something. But if it's the original PFC IC replace it.

[hobostove]

Found an open resistor near the PFC IC, has a hole in it. Replaced it and now 5VSB is shorted again. Getting there!

[CapLeaker]

Hmm… how can a resistor change kill the 5VSB?