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Building a replacement power supply

SentryP

May 28, 2011
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May 28, 2011
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I have three DS0-142L power supplies that aren't working. They are for a 16 port HP KVM and I can't find replacements.
The issue is I'm new to electronics and I don't know how to troubleshoot this.

I have given up troubleshooting them and would like to build a replacement.
I have seen lots of how to's on the internet on building a power supply but none of them meet my voltage requirements.
Could you please help me understand what I should build to replace the power supply. I assuming I could do it with a wall-wart and a some transistors.
Either way I guess I would need a parts list and a drawing. I can solder!

Any help would be great.
I have attached a picture that I found on the internet.


Thank you
 

davenn

Moderator
Sep 5, 2009
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ok so replacing the faulty caps didnt get the supply working again ?

in you pic I assume you incorrectly stated the output V and A values ( the ones at the bottom of the pic ?
I assume the block diag notes at the top are the corrct values ?

Dave
 

SentryP

May 28, 2011
5
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May 28, 2011
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Yes you are correct!
I did try replacing the caps on two of them and it didn't work.

The voltage at the top of the page is correct.
The sticker on the power supply reads, +5.1V / 2.4A, -5 V / 0.5A

THANK YOU for helping me with this!
 

davenn

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Sep 5, 2009
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ok :)

Are you getting any voltage out at all ? even just 1 or 2 V on the 5V rail ?
how about the -5V rail ? is there any voltage on the input pin of the 7905 regulator ?

Is the fuse on the primary side intact or blown ?

Dave
 

SentryP

May 28, 2011
5
Joined
May 28, 2011
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Are you getting any voltage out at all ? even just 1 or 2 V on the 5V rail ? -- None
how about the -5V rail ? -- None


is there any voltage on the input pin of the 7905 regulator ? - a little but it seems to be jumpy I get a max of 2 volts

Is the fuse on the primary side intact or blown ? Intact
 

New2Me

Dec 6, 2011
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Dec 6, 2011
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DSO-142L Replacement

I tried to find one to no avail. In the meantime, I used an ATX power supply from an old computer that was lying around. I cut the three wires for the 3 pin connector off of the DSO-142L and connected them to the power supply motherboard connector - I tinned the ends and they fit nicely into the female connector. You must find an ATX supply with a white wire, that is the -5 volt supply needed for your DSO white wire. The red goes to a red for +5 volts, and the black to black for common. The ATX power supply that I used also needed its green wire connected to a black to power it on. I removed the on-off switch from the back of the KVM case, installed a grommet, and ran the wires out through it. I used hot glue to fashion a "connector" out of the three wires so that I can plug in to another power supply if this one dies. I zip tied the supply to the back of the rack. Worst part of the whole deal was KVM removal/installation in the rack, there wasn't a lot of room!
 
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