Light Bulb Trick for power supply testing with blown fuse

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  • jstiene
    Senior Member
    • Feb 2013
    • 148
    • USA

    #1

    Light Bulb Trick for power supply testing with blown fuse

    Hello.

    I am trying to locate an article or get direction on how to use a light bulb while troubleshooting a PS that is blowing fuses. I am using a 75w bulb across the fuse junction, but what i am trying to understand is what I should see in terms of the bulb lighting/etc after I replace the suspect parts. Also, will the TV actually power up with the light bulb in place? Any help would be appreciated.

    Thanks!
    Joe
  • Caleb
    Smokin IC's
    • Feb 2013
    • 645
    • USA

    #2
    Re: Light Bulb Trick for power supply testing with blown fuse

    If you still have a short the bulb will glow bright the whole time, the shorted component(s) will warm up first, so you can use canned air upside down to freeze components and see what warms up first. After you get the short cleared the bulb should come on for a second or two then go out after the main caps are charged. Depending on the wattage your power supply is trying to power you may get it to power on with the bulb in place but most likely not, you can put two 100 watt bulbs in parallel to provide more juice and possibly get it to power on.
    Liberating magic smoke one part at a time

    Comment

    • tibimakai
      Badcaps Legend
      • Jan 2012
      • 3680
      • USA

      #3
      Re: Light Bulb Trick for power supply testing with blown fuse

      Budm has a thread on this somewhere.

      Comment

      • selldoor
        Slow Learner
        • Dec 2010
        • 7870

        #4
        Re: Light Bulb Trick for power supply testing with blown fuse

        Perhaps try typing "light+bulb" into the search facility above - not all will relate but you
        should find enough to help
        Please upload pictures using attachment function when ask for help on the repair
        http://www.badcaps.net/forum/showthread.php?t=39740

        Comment

        • momaka
          master hoarder
          • May 2008
          • 12170
          • Bulgaria

          #5
          Re: Light Bulb Trick for power supply testing with blown fuse

          Generally the TV won't be able to do a full power up with the light bulb in series. The light bulb trick is only good to see if everything is okay initially (i.e. the PSU doesn't blow up parts after a major repair).

          It's normal for the light bulb to light up for a second or two after you apply power, but if the bulb stays lit, you still have a problem somewhere. For PSUs with APFC, the bulb may cycle ON-and-OFF very rapidly for a few seconds. This is normal. However, if the light bulb doesn't dim or turn off, you have a problem.

          Comment

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