Startup of server PSU "N7K-AC-6.0KW"

[Gady159]

Hello,

At the beginning, I would like to apologize that I write in English on the German forum, I am from the Czech Republic and I only know English and Russian So I hope it won't be a problem..

I recently purchased a Delta "N7K-AC-6.0KW" server power supply used in Cisco servers.

Unfortunately, there is very little information about these resources on the Internet, specifically I found only one page on reddit where the resource was addressed, I found suitable information there.

https://www.reddit.com/r/Cisco/comments ... kac75kwus/

(This is a 7.5kW version, but it should be basically the same source)

I found more posts on this forum regarding other cisco resources.. for example:

viewtopic.php?t=63559
viewtopic.php?t=64061
viewtopic.php?t=64921
viewtopic.php?t=64921

I have one of these PSUs and they will turn on as I connect 230VAC to both AC inputs and turn the switch ON.



But this N7K-AC-6.0KW blinks red LED fault as I connect 230VAC to both inputs, turning switch ON does nothing. Seller sold these PSUs as Used but fully functional. So i dont know if its broken or i just need to bridge some digital pins at the back.

So I would like to ask if anyone has experience with this source and how to turn it on.

Thank you very much everyone in advance!

Images:
https://imgur.com/a/bw9ZAKe

[reklm]

Hey Gady,
I think it should work if you put a load on it, like a high ohm resistor. Some server power supplies need a load to start. Maybe that will solve the problem. Greetings from Germany

[Gady159]

Hi, thanks for reply..

I tried with load but still RED LED blinks (Fault)

I guess whole PSU is OFF like (power supply + PFC is both OFF)

[reklm]

Are the 2 230V AC Inputs the same Phase or did you use different ones.
Nevermind: ...or using just one input will produce lower output power levels.
1x 220V ==> 3000W

[Gady159]

I used same phase and Green LEDs Input 1 and Input 2 is lighting up.

According to informations on internet only voltage is important with these PSUs...

USA 110V is low (half power), EU 230V is full power and same think if you use only one PSU...

[reklm]

Did u try the things from reddit.
"You can turn it on by shorting the middle pin of the top to the bottom middle one, it will still show failure but it will turn the output on "

[Gady159]

Yes i read this but i did not understand from what angle ot view of ports is bottom and top middle connector...

You know am worried about shorting something and destroying that PSU forever.

Did you understand better than me which pins it can be?

[reklm]

I thought the upper Control/Data Pins but it seems that they are even so there is no middle one. I also got a Cisco PSU but not the same as you and it just works without any other modifications. I think it can work if two pins are connected but we dont know which ones. Can u look inside thru the ventilation or so . Maybe there is a green wire and we can connect it to ground like the atx psu.

[Thunderbolt]

I have few SUN power supplies that need two pins shorted together to start (I think one of the pins is +5Vstby).

try probing the Control connector to find some supply voltage (5V or something), from that you can tell where GND is
then probe every pin against GND.

then you can grab a resistor of ~1k or something and start connecting each pin to +5V and measure the voltage on the pin against GND
the do the same thing with the 1k resistor agains GND

if you're lucky the PSU will start.
otherwise you at least have a starting point to see what pins might be inputs

[Gady159]

Inside is row of grea cables like IDE cables from HDD if you remember.. so by color i cant define which pin will that be....

[gamerpaddy]

Looks like theres a atmega64 or 2560 working in it


can you take that board out, take proper pictures and measure where each pin goes (inputs are usually opto coupled or buffered before doing anything, by the direction the opto or buffer is you can determine if its a in or output.

[Gady159]

Ohhh nice

I suppose you find it somewhere what are you using for searching?
Yes i will make clear photos and send it here and try measure things...
I will try measure if pin is supply (like +5, +12 or +3,3V) or data pin going through buffers to MCU.

But I'm a little nervous about the fact that not only pull-down or pull-up but some specific voltage to the analog input of the ADC will not be necessarily to activate the PSU (I'm just guessing).

How should I figure it out then?

[gamerpaddy]

check which pin goes to a ADC or analog input pin the atmega.. thats a analog pin then

but i doubt it, it probably just a few pins to bridge. worst case might be a digital protocol like can bus, spi, i2c etc. to send activation commands

[Gady159]

Yes there is ATMEGA 64A and some buffers LTC4303.

I have different batch of this board. 2 6 or 8 layer boards soldered together... so probing where signal trace go will be kinda hard...

[Thunderbolt]

Yes there is ATMEGA 64A and some buffers LTC4303.

I have different batch of this board. 2 6 or 8 layer boards soldered together... so probing where signal trace go will be kinda hard...

The the procecure I suggested might be the way to go
at least it worked for my SUN 48V/30A server power supplies