using 12V power adapter on a 9V wifi modem?!

Discussion in 'General Electronics Chat' started by rezamoezzi, Dec 28, 2015.

  1. rezamoezzi

    Thread Starter New Member

    Dec 28, 2015
    1
    0
    I used an 12V adapter for my modem(philips SNB5600) instead of 9 volt.
    It was working but just after 10 seconds it made a noise and It didn't work anymore.
    So I want to ask,what exactly happened and is there any hope to fix it and how can I repair it?
    Thanks
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    You will have burnt someting inside the modem.
    It was rated for 9 Volts and you applied 12 Volts, so over voltage might lead to over current and burning stuff.

    Bertus
     
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  3. JohnInTX

    Moderator

    Jun 26, 2012
    2,342
    1,024
    The adapters may also have had different polarities - zap!
     
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  4. Roderick Young

    Member

    Feb 22, 2015
    408
    168
    If you have a multimeter, check the voltage on the 12V adapter. Is it really 12 volts? Maybe it was an old unregulated type, and due to the light load, had a much higher voltage.

    As to what happened, was the sound like something popping? What did it sound like? Was there a smell, especially a burning smell? Open the modem, looking especially for burned components or bulging / leaking capacitors. Post a picture here, if you can. The most reliable thing to do would be to simply get a new modem rather than trust one that has been exposed to overvoltage, but I'm assuming you're interested in what happened.
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,791
    1,103
    Any resistive component receiving 12V instead of 9V would generate 78% more heat than it was designed to! Not surprising if something fried :(.
     
  6. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
    619
    No one can tell you exactly what happened or how to repair it.

    Chalk it up to experience. Buy a new one and pay more attention to details in the future.
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    783
    Wouldn't have worked for a while if that happened.

    Most modems I've ripped for parts, had at least 3 SMPS regulators for on board rails - some are buck with series control transistor/MOSFET, if they fail short circuit; the unregulated juice hits the logic supply rails and its game over.
     
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