Disk array power supply pinout/wiring


Sorry for crossposting this, but I've had no answers from the more specific groups.

I'm in the process repurposing a power supply from a scrapped Sun Microsyst ems StorEdge D2 array which was working perfectly well when decomissioned.

It is a Japanese made 360W FDK PEX737-40, +5V/30A and +12V/23A. Impressively well built hardware and in mint condition.

The final objective is to have a PS with solid +12 and +5 outputs which may eventually power USB charging ports and other assorted stuff needing quali ty power.

The plug at the back of the slide-in box/canister has 24 pins just like the typical male Molex 39-01-2240 connector for ATX MBs but with a different p inout and keying(?) and without all the usual ATX voltages, which makes sen se as it is not a for a motherboard.

Of the 24 pins, 19 have 18AWG and 5 have 24AWG cables.

With the unit plugged in and the rear switch 'on', I get these readings:

18AWG-red -> 0.00V to GND 24AWG-red -> 3.0mV to GND 18AWG-orange -> 0.00V to GND 18AWG-yellow -> 0.00V to GND 24AWG-green -> 0.00V to GND 24AWG-grey -> 0.00V to GND 24AWG-blue -> + 5.08V to GND + 3.0mV to GND

This would make the blue cable PS_ON but the unit will not latch_on when I short it to GND and although there's no continuity between the green cable and GND, the unit does latch_on when I short blue+green.

The five +5V cables are on the same rail as they show 0.1 ohms between them , same for the three +12V cables.

The remaining red cable shows 10.2 ohms to the other +5V cables.

The yellow +12V cable shows 3.80k ohms with respect to the other +12V cable s and is probably destined to one of the two redundant fans the array had.

With the unit plugged in, the rear switch 'on' and green+blue shorted, the unit latches_on and I get these readings:

18AWG-red -> + 5.11V to GND 24AWG-red -> + 5.10V to GND 18AWG-orange -> +12.29V to GND 18AWG-yellow -> +12.01V to GND 24AWG-green -> + 5.07V to GND + 5.06V to GND + 5.10V to GND + 5.10V to GND

So my guess is that the blue cable is PS_ON, the grey cable is PWR_OK and t he green cable GND (?).

What I would need to know is this:

The 24AWG-red cable has no voltage when the unit is not latched_on, so it d oes not seem to be +5VSB: what is it for?

What would be the proper use of the brown cable? Is it a sense cable like every other ATX PS?

Do I need to put in a dummy load (10 ohm/5w sandbar resistor) to insure sta bility?

I'd be grateful for any input on this.

Thanks in advance.


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Found blue+green mentioned in the last post here as power on.

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24AWG-red on a 10ohm resistor (trace it?) connected to the main 5v rail, I'd guess would be a power_good indication. The Sun array might be in a redundant dual PSU configuration, and this could be just a monitoring wire.

Likewise with the brown.

I wouldn't get too hung up with checking deviations from the ATX standard which possibly isn't valid here anyway. However, I would as an exercise check with a meter or a scope, voltage stability at low current draws.

I'd think seriously about adding properly fuses in the output, when attaching anything to it - or being especially careful with it. I have personally experienced burning cables (and skin!) on things less potent.

Adrian C
Reply to
Adrian Caspersz

That was me. 8^) I was attempting to reach the poster who knew the solution was blue+green, hoping he'd know about the brown and red cables.

No, haven't traced it but it is on the same rail as there's continuity.

Wouldn't that be the grey 18AWG wire? The front panel on the array had an amber/green status LED. Green for 'no error condition' and amber for drive/fan/PS or temperature error.

Yes, it is very well designed: redundant PSU and Fan canisters.

That is what I've been thinking, especially being 24AWG. But if it is a voltage monitoring function like the 3.3V sense wires in the ATX design maybe(?) would be necessary for stablility.


Yes, I have to set up a test rig once I get everything mounted. But no scope, just a mid-quality RMS meter.

Of course.

I still have draw up how I'll divide this all. Probably two separate +12V posts, two separate +5V posts and two stacked USB charging plugs, everything properly fused.

I still have to decide if I'll be using 5x20mm panel fuses/holders or maybe spend a bit more and wire in polyfuses, particularly on the USBs.

Thank you very much for taking the time to answer.



Reply to
Julius Henry Marx

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