12 V 1.25 Supply

Discussion in 'General Electronics Chat' started by ihateCaptcha, Mar 8, 2012.

  1. ihateCaptcha

    Thread Starter New Member

    May 10, 2010
    7
    0
    I have a 12 volt, 1.25 amp supply for my wireless router. Every two weeks or so, the zener diode inside shorts out. I'm tired of replacing it. Is this because I plug it directly into the outlet with no protection or is it a design flaw. Will buying a proper UPS solve my issue ? Thank you for reading this. :)
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    Where is the zener diode placed? What value has it? Did youcheck on the net if others experiencend the same problem?
     
  3. ihateCaptcha

    Thread Starter New Member

    May 10, 2010
    7
    0
    the diode is placed at the very end of the circuit. (just before the output) and it's a 1n4004 (if I see it correctly). Of course the easy solution is to buy it online, but for the sake of tinkering, I'd like to know what's going on.
     
  4. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    That's not a zener diode. Looks like the rectifier diode of the transformer. Is that correct? What else is connected to the diodes cathode? Capacitors etc. What is the routers power consumption?
     
  5. ihateCaptcha

    Thread Starter New Member

    May 10, 2010
    7
    0
    you are right, it's not a zener. I can barely make out what's going on because the components are filled with that white goo, to keep em' in place i guess. 2 caps are connected to it.
     
  6. ihateCaptcha

    Thread Starter New Member

    May 10, 2010
    7
    0
  7. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    Ok this IS probably a zener. See also the component name (ZD1). Do you still have the original one?

    It then cannot be the 1N4004.

    If you want to know why it gets damaged and what it is for you will need to draw that part of the schematic diagram.

    Somewhere there should be a resistor in series with it...
     
  8. ihateCaptcha

    Thread Starter New Member

    May 10, 2010
    7
    0
  9. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    It advertises "for any device that requires stable DC power. ", so I guess it is also a switched mode power supply (as yours probably is, it has a ferrite core transformer).

    Just compare the polarity of the connector you have and the one you want to buy. The one on the website has the + pole inside. Also it's dimensions.
     
  10. ihateCaptcha

    Thread Starter New Member

    May 10, 2010
    7
    0
    I'm not that worried about the connector. I could just chop off the one attached to this supply. The center is the positive.
     
  11. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    Then go and spend some money. :D

    Or try to repair your power supply and learn something. ;)
     
  12. ihateCaptcha

    Thread Starter New Member

    May 10, 2010
    7
    0
    I'll just do both. After I'm done fixing it, I can always plug it back it or have it as a backup.
     
Loading...