SlantS

I bought this Mad Dog 550W modular psu refurb (poorly refurbished) with an expired warrenty. It was only 10.00 to me so it seemed worth it at the time.
Item was supposed to be tested and working.
This psu has sata/pcie connections, the 4 pin p4 connection, and a 20/24 pin atx connection.
This psu failed to even make a noise when I hooked it up to an older P3 setup.
I also tried jumping the psu with a wire from green to black (pins 14 and 10 I believe), and still nothing.

I only located one fuse and it does not appear to be blown, but I am not sure if these fuses even look any different when they do go out.

Could it be that I am not correctly testing this psu? I do not want to hook it up to my new setup to test because honestly I do not want to risk a nice computer for a 10.00 psu.

I do not want to simply toss this psu given that most of the parts (including capacitors) should be in working order.

Does anybody have any ideas?


Fuse appears to be ok

shinji2k

It's hard to tell from the pic but is the fuse removable or soldered in? To tell if the fuse is blown the little wires inside will be broken (normally they span from end to end). It also sounds like you are jumping it properly. Try using different ground wires (black). There are a few in the mobo connector and sometimes you have to use a certain one to jump it. All in all, in doesn't sound like the PSU is in good shape.

edit: If the fuse is fine and you still can't jump it have a quick look around for anything that looks burnt or melted (but be careful not to touch any of the capacitors), pay special attention to the components screwed to the heatsinks. If something failed it will most likely be melted and/or burnt.

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Chozart

$10 refurb Mad Dog?

Don't even try. I would not even let a new Mad Dog get any closer than 1 mile from my rig. Get a good PSU. Please.

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shinji2k

Heh, nothing of value will be lost if it is dead .

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SlantS

The psu is supposed to be some sort of knock off from a larger company.
They sold these at comp usa as a surepower 550W for around 120.00 in 04.

The fuse is soldered in. I tried jumping the fuse with another inline fuse I had, and nothing. I also tried using a different black connection with no results.
I guess I will strip it down when I get bored, replace the fuse just to be sure, and see if there are any ovbious defects.
I know not to touch the capacitors, but I am even thinking of discharging or removing them before I really handle the main board. Just in case I slip up lol.

Any input would still be appreciated.

shinji2k

Sounds fun, I like tinkering with stuff too . Well, it's not a knock off (I don't think at least). It is built by Super Flower for Maddog. They can make some good stuff if they try but it is up to the client (Maddog) to determine what kind of quality to build.

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SlantS

Ok I believe I pinpointed the problem.
I stripped down the entire psu, no burns at all.
I still re-soldered all of the connections that looked like they could be faulty (and then some)
Replaced the fuse
And still nothing.

I tried running through the traces with a volt tester and came to this one spot where the current would not pass, plugged in or not. Yes, I briefly worked on it plugged in (Not the best idea ever)
I tested the current from one side of this piece to the other and got nothing.
Then I grounded my volt tester and hit the incoming side of this piece with the positive end
(set on ohm X1k) and the entire thing fired up!

Turned it off, did it again and it worked!

I did not test it on a computer, I want to replace this part just to be sure it is the problem. + I dont want to jump start a psu while it is connected to a computer.

I am definetly going to have to assume that this one piece is faulty. Anybody have any idea what it does or why it would go bad?


(forgive my sad sodering job on the fuse)

Btw, the left and right sides of this piece are connected on the back side.


There are some small numbers on the top. They are in this order:

C03M0 ( I am pretty sure but the writing is very small )
1070
B17
F42

In you know anywhere to find these please post a link, that would be sick.

And how about a +rep for the find!?

mrtn400

Asking for rep for finding the answer to your own question. FFS man.

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SlantS

dragonxwas

the part you pinpointed is an opto isolator or also known as an opto coupler ,


this is the weakest link of every smps or psu,,
jus go to st.com type in the numbers written on it,you might find the part or an substitute for it,

jus radio shack it and replace in,your psu should function just.. fine