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Building a replacement power supply

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Discussion in 'Power Electronics' started by SentryP, May 28, 2011.

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  1. May 28, 2011 #1
    SentryP

    SentryP

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    May 28, 2011
    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.
    [​IMG]

    Thank you
     
  2. May 28, 2011 #2
    davenn

    davenn Moderator

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    Sep 5, 2009
    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
     
  3. May 28, 2011 #3
    SentryP

    SentryP

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    May 28, 2011
    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!
     
  4. May 28, 2011 #4
    davenn

    davenn Moderator

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    Sep 5, 2009
    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
     
  5. May 28, 2011 #5
    SentryP

    SentryP

    5
    0
    May 28, 2011
    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
     
  6. Dec 7, 2011 #6
    New2Me

    New2Me

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    Dec 6, 2011
    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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