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[update: added trace of pins]

I needed a chunky 12V power supply, and I have found one of these HS0550 which is rated to supply 12V @ 45.2A according to the spec; enter image description here

enter image description here

It was surplus from an old HP StorageWorks XP20000 system. However none of the pins on the back seem to be giving +12V relative to what I think is GND. (there are pins with +3.6v and +4.68v)

enter image description here

Googling the product code suggests it's manufactured by Hitachi as a "HITACHI 5529219-A USP-V DKU POWER SUPPLY"; http://www.serverworlds.com/hitachi-5529219-a-usp-v-dku-power-supply/

Unfortunately, I can't find any docs on either the code 5529219-A or "HS0550"

I don't recognise the pinouts, but those connectors are actually adapters and can be removed, which gives 5 blocks of 6 pins;

enter image description here

I presume that these supplies use something similar to the ATX power supply standard, and require shorting across pins, or some other signal to enable to the 12V line; http://www.techpowerup.com/articles/other/22

But I can't find any explanation of what power standard this PSU is using...

Some general troubleshooting seems to suggest that the unit is working, as I can find 9v at some points on the board when powered up, and there is a test point which is reading something like 418v DC;

enter image description here

Here are some shots of the top and bottom of the board;

enter image description here enter image description here

I've traced out the pins, and the brown trace looks like it should by the one carrying 12V. I think the blue trace is the signal for connection pin.

There are 3 opto couplers in the centre which I think are being used to switch on the main 12V circuit. 2 are connected to one daughter board, and then the other to a separate daughter board with the 12V level adjustment.

enter image description here

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This PSU activates if you short pins 5-3 on J05 with a 1-1.5K resistor. If you change the voltage regulator (500Ω) to 1K, this PSU can output 14.2-14.5V (for charge 12V acid battery up to 400 Ah). For the best cooling, it is recommended to close the top and side vent, only open the backside.

PSU photo

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  • \$\begingroup\$ I haven't got the unit anymore to test it, but it sounds like it would be the correct answer! ;-) \$\endgroup\$ – Tom H May 28 '18 at 15:49
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It should be "relatively easy" to find the 12v source. Since it is capable of supplying 42A, it will have wide lands going to the output socket(s). Typically, this voltage comes out a voltage regulator (which looks like a transistor), which typically is mounted on a heat sink. If the current is distributed, it might be the case that you have 6 regulators, each providing 7A. If it is only one, then it would be even easier to find, it is the one with the largest heat sink!
If there is no over voltage, over current protection, you might need a load resistor to be able to "see" the voltage (try a 12 ohm 25W).
Once you locate the regulator you should find one lead at 0v, one at > 12v and one at <= 12v. This last one is your 12v output source.

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  • \$\begingroup\$ I've probed most of those obvious points, and I am fairly convinced that the board is looking for a signal to enable the 12V. In the centre (marked in yellow) are 3 opto-couplers which I think are used as part of that mechanism. \$\endgroup\$ – Tom H May 9 '15 at 6:57

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