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Thread: DM500s Power supply repair.

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    Senior Member z80's Avatar
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    Default DM500s Power supply repair.

    Got a bit sick of these cheap clone 500s power supplies failing.

    Got a few in the junk box now, even though they are cheap i find they fail at the worst possible times.

    so...pulled one apart and found that they all had the same fault.

    It's one of two 25v/470uf caps.

    The usual chinese crap....of course the jaycar replacement with identical specs is bigger.

    any way....so you don't have to re-invent the wheel here are the photos.

    (as always...be careful...deadly voltages inside for a few minutes after power removed)


    Just wack the PSU flat on the ground and the seal will release for access.
    (Araldite will reseal it with some tape to hold in place while it sets.)



    The FAULTY cap is marked red at the top...






    Here it is all fixed.




    TOTAL cost?.....$1.10c Australian....

    Enjoy...



Look Here ->
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    thanks ...
    It is a hobby so mileage varies
    Loving IPTV with XBMC and android M8
    Join in the XBMCHUB community and visit me at http://tvaddons.ag/

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    Wow. The recession must really be biting

    Yep, the 470uf caps can be a bit of aproblem.
    I've changed them before.
    I would recommend changing all the electrolytic caps while it's open. The same as any other SMPS
    Reality is an invention of my imagination.
    ಠ_ಠ

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    so when you wack the psu the case comes apart fairly easily? Or do you really need to wack them?

    Leroy

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    Good one z

    KK.

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    About as much of a knock with a hammer as for driving home a small nail. Nice sharp taps are the answer
    Reality is an invention of my imagination.
    ಠ_ಠ

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    Good info there z80,..

    cheers

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    just gave my dead supply a "squeeze" and it popped open


    ahhh - dead 470uF



    thank you

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    Senior Member z80's Avatar
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    Quote Originally Posted by Fernbay View Post
    Wow. The recession must really be biting

    Yep, the 470uf caps can be a bit of aproblem.
    I've changed them before.
    I would recommend changing all the electrolytic caps while it's open. The same as any other SMPS

    I'm much too tight arsed to change them all....

    ( I unsolder them from used Intel 486 motherboards...LOL)

    @Guys- thanks for saying thanks, makes it worthwhile to share info.

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    Quote Originally Posted by z80 View Post
    Got a bit sick of these cheap clone 500s power supplies failing.

    Got a few in the junk box now, even though they are cheap i find they fail at the worst possible times.

    so...pulled one apart and found that they all had the same fault.

    It's one of two 25v/470uf caps.

    The usual chinese crap....of course the jaycar replacement with identical specs is bigger.

    any way....so you don't have to re-invent the wheel here are the photos.

    (as always...be careful...deadly voltages inside for a few minutes after power removed)


    Just wack the PSU flat on the ground and the seal will release for access.
    (Araldite will reseal it with some tape to hold in place while it sets.)



    The FAULTY cap is marked red at the top...


    TOTAL cost?.....$1.10c Australian....

    Enjoy...
    Quote Originally Posted by Fernbay View Post
    About as much of a knock with a hammer as for driving home a small nail. Nice sharp taps are the answer

    You haven't seen my knock Fernbay lol. Thanks guys. I'm sure this will come in handy!

    Leroy

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    Quote Originally Posted by z80 View Post
    so...pulled one apart and found that they all had the same fault.
    It's one of two 25v/470uf caps.
    Interesting. The PSU that failed on me awhile back, had 1000uF/16V caps installed instead of 470uF/25V.
    Replaced them and all was ok

  • #12
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    God bless the people that made Caps $$$$$$$$$$
    When you do things right, people won't be sure that you have done anything at all

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    Thanks for sharing, good to know.


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    Thanks z,

    Another one for the archives.

    Will come in handy down the track, as did the Humax PS problem/fix.

    Thanks to vk6xlr for the input/update

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    the same happens with the clone 7020s, the cap on them is 47uf 400v, i replaced one only last week to bring one back to life at a cost of 1.06 GBP

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    Thanks Zed, the clock is ticking, im sure mine will fail with time.

    At least i know what to do now.

    Thank you.

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    I can't believe after all the effort of taking out the old capacitor you replace it with another worn out one! Now that really is tight arsed!

    Nice work, thanks for sharing.

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    Hes being green and recycling.

    (Read looking after his pockets).

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    Exclamation

    Safety reminder to people working on switchmode power supply
    1. As Z80 said, unplug and allow a few minutes for it to discharge before handling.
    2. Always use a capacitor of equal or higher voltage rating (never lower!)
    3. Always observe correct polarity (insert it the right way around)
    4. Check area around power supply is clear of anything metal before powering back on.
    5. Don't work in bare feet or around moisture
    6. Keep fingers, children and cat well away while plugged in!


    If you're the paranoid type like me, after waiting for discharge you can manually quench each dangerous capacitor, ie any with voltage rating over 63V. Ideally you'd do so using a , but if you know it's 95% discharged already you can get away with a screwdriver.

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    I repaired one of my power supplys last week,same cap etc.The symptom my supply had was a pulsing on and off as seen by the green led flashing. I was lucky to get my supply open by twisting it and getting the glue to give way at one end then using a small watch maker screwdriver to clip the two halves apart.

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