Custom Power Supply - Page 1
Forum section: electronics / beginners

author: ArnoldJRimmer
author_rank: Newbie
timestamp: August 12, 2015, 04:02:41 pm
content: I acquired 3 monster power supplies that were destined for the recycling center. They seem to be custom designed. They have a main power switch but do not have a 20 or 24 ATX connectors. I guess they power up from sensing load. As a newb with the courage ignorance I connected the molex connector to an old harddrive. It powered up alright and melted the two ground wires together. How could I bring them up to test their output safely?

author: mariush
author_rank: Super Contributor
timestamp: August 12, 2015, 04:23:05 pm
content: Looks like a Sirfa (Sirtec / High Power) or another OEM design...See that green wire that goes into the PCB and it says there PS-ON ? The power supply should start when you short that green wire to ground (a black wire).The odd 4wire connector in the second picture may be [power-on | ground | ground | 5v stand by ] but I'm not sure. Grab a multimeter, plug the psu in the mains and measure?The board has two dc-dc converters (the small boards with polymer capacitors) for 3.3v and 5v but I don't see any 3.3v wires .. I see only a pink wire which could be -12v but best to check it with multimeter.Keep the board on a piece of cardboard or something that would insulate it from everything and don't touch the primary heatsink, even though it should be safe to touch.The power supply in the picture looks like a 520-650w-ish model based on the two primary capacitors (too much capacitance for a ~ 400w psu) and the 4 pci-e connectors.later edit: if you get it working and you keep the power supply running for long periods of time you should add a fan blowing over the heatsinks.

author: Mephitus
author_rank: Regular Contributor
timestamp: August 12, 2015, 04:35:57 pm
content: Judging the build of it and its output rails, it looks like its a dedicated PSU for videocards being used in tandem. Looking around I cant seem to find anything that fits that exact build. Could be they threw it out because it wasnt operating within spec. It would probly be a good idea to use a dummy load to test it to make sure it doesnt blow up whatever you connect it to. Good find, would love to have one myself.Edit: Thinking about it some more and how it is without a case, I am willing to bet someone was using it for bitmining with GPU's in a custom rack. Since ASIC's have been made that now make that mining method obsolete, that could explain why it was thrown out.

author: ArnoldJRimmer
author_rank: Newbie
timestamp: August 12, 2015, 05:35:55 pm
content: Thanks for the info.They have cases with a fan that covers the entire surface of one side. There were over 100 going to be recycled from a discontinued product line from where my brother works. He works the warehouse and has no other info. Came bubble wrapped in white boxes without any labeling and no stickers on the case.The 4 pin connector that looks like a atx harddrive molex shows 3.3v on pin 4 and nothing on pin 1. Pin 4 leads to the board marked 5v. The first test was to power an old harddrive. Although it smoked the harddrive the fan came up. What could I use for a load to trick it into powering up?

author: Mephitus
author_rank: Regular Contributor
timestamp: August 12, 2015, 06:44:18 pm
content: As Mariush said, likely if you ground out the green wire, it should start up. Do you have a multimeter and soldering iron? If so, you can build a very basic/cheap dummy load like this:http://www.k4eaa.com/dummy.htmlYou can then use your meter to check the output from the board.If they really are dedicated graphics PSU's, as I suspect, I would nab as many as you realistically can.At the estimated 500w+ output from them, they can definately still find a good use. Hell, if nothing else, you can sell them on ebay as such for at least $50/piece. My PSU for my PC is 750w and I would still enjoy having a dedicated GPU power supply.

author: ArnoldJRimmer
author_rank: Newbie
timestamp: August 12, 2015, 08:02:39 pm
content: Thanks guys. Jumping the green wire to ground did the trick. I was a bit leery of trying that considering it smoked a HD connected to that plug. So I jumped it through a .8A breaker.Now I need to find a use for a PS with 10 12v taps.

author: Mephitus
author_rank: Regular Contributor
timestamp: August 12, 2015, 09:40:16 pm
content: What state are you in? I could use one for my current setup.