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Old 06-24-2014, 04:31 AM   #1
Darksteel
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Default What can you tell me about this...PSU?

This one is from 2003 or older. It used to power my old P4 1.8Ghz system. I had used this PSU for one or two years. After that, it was laying around.

Recently, I needed a 12V power supply to be used as a car cigarette socket. I'm planning to use this with a 12V 10A air pump. From the look of the internals I'm not sure it will provide 10A without exploding.

What could you tell me from the pictures please?











http://s15.postimg.org/8fdgdmtnv/IMG...623_195656.jpg
http://s15.postimg.org/p5ou2ys2z/IMG...623_200046.jpg
http://s15.postimg.org/npdbktp63/IMG...624_144119.jpg
http://s15.postimg.org/44ysi1okr/IMG...624_144154.jpg
http://s15.postimg.org/csgl9srsb/IMG...624_144331.jpg
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Old 06-24-2014, 01:37 PM   #2
Gabriel Torres
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A piece of ****.

Old half-bridge design with regular diodes at the secondary. Doesn't even have a transient filtering stage.

It probably has 70% efficiency.

Last edited by Gabriel Torres; 06-24-2014 at 03:20 PM.
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Old 06-24-2014, 03:13 PM   #3
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I wouldn't put that in a computer (Unless you really don't case if it kills it). If you are using it to power anything else, then it might work, but it looks like it only has two 3A diodes on a bracket for the 12V rectifier, meaning that the 12V rail is not theoretically capable of more than 6A. If you are good with a soldering iron, then you could replace it with something like a 16A fast recovery rectifier and it might do OK for something like your pump.

Personally, though, I would just give it a good hit with a sledge hammer and give it to the metal recyclers.

Last edited by c.hegge; 06-27-2014 at 03:26 AM.
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Old 06-25-2014, 05:56 AM   #4
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Your replies just made my day.
Thank you.

I thought that old psu could be converted into a 12V source for non sensitive car accessories like an air pump or incandescent light bulbs.

I was planning to add something like this:


If this one was a more reliable psu, a power box with different connectors and voltages could be made with it.

I've abandoned the idea, for it's not worth the effort.
Maybe, when I find some time spare time, I can replace those diodes with a mbr2545 and see what happens under heavy load.

But now, I'm looking into DIY sledge hammer projects!
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Old 06-25-2014, 02:01 PM   #5
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The MBR2545 only has a PSU repetitive reverse voltage (VRRM) of 45V. A part with a VRRM of 100V or higher is recommended. I know of others who have used similar parts with 45V VRRM on other pert supplies - only to have them fail after a few minutes.
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Old 06-26-2014, 06:37 AM   #6
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Quote:
Originally Posted by c.hegge View Post
The MBR2545 only has a PSU repetitive reverse voltage (VRRM) of 45V. A part with a VRRM of 100V or higher is recommended. I know of others who have used similar parts with 45V VRRM on other pert supplies - only to have them fail after a few minutes.
You know PSU's like the back of your hand.
It was impossible to read the diodes so I disassembled them.

No surprise, FR302 s.
3A each like you said in your previous post and 100V.

I'll find something like mbr20h150ct, stpr1610-1620 or something similar.

There are signs of overheat at the back of the PSU PCB. Where those FR302s were connected. Dust gathered around that area burned/melted.
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Old 06-27-2014, 03:26 AM   #7
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One of those two rectifiers would work fine. The heat discolouration you see on the PCB is because of how undersized those diodes are. 6A is really pushing it on a P4 system (where the CPU is powered solely by the 12V rail, and that will cause them to run very hot (and probably have a very short lifespan).
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