Dropping LED voltage on 17IPS20

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  • speedypro
    Badcaps Veteran
    • Feb 2013
    • 561
    • United Kingdom

    #1

    Dropping LED voltage on 17IPS20

    Continuing from this post, I like to update on my other finding, before I conclude it's a led strip issue.

    Removing where the led wire connects to on the psu, I placed a MM to read the voltage. It reads 50v but keeps going down; down below 30v! Is this normal? What causes the voltage to be dropping.
    Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer
  • Dannyx
    CertifiedAxhole
    • Aug 2016
    • 3912
    • Romania

    #2
    Re: Dropping LED voltage on 17IPS20

    Originally posted by speedypro
    Continuing from this post, I like to update on my other finding, before I conclude it's a led strip issue.

    Removing where the led wire connects to on the psu, I placed a MM to read the voltage. It reads 50v but keeps going down; down below 30v! Is this normal? What causes the voltage to be dropping.
    Does this TV turn on AT ALL ? What you're describing sounds very much like a failed backlight LED. The power supply has just cut the power going to the LED strips, so those volts you're getting is the caps discharging after they've received some brief power. With the TV off, the red lead going to the LEDs should read around 24v from what I know. When you switch the set on, it should first jump to 100+ volts, then stabilize at around 85v with a functional backlight. A faulty backlight will still shoot up to "something" volts briefly, but will begin dropping as you describe because the IC in control of the backlight senses there's no load and shuts off. This is a very common issue on Vestels.
    Wattevah...

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    • ReeceyBurger123
      Never Give Up !
      • May 2014
      • 7325
      • Britain

      #3
      Re: Dropping LED voltage on 17IPS20

      Your Psu is faulty if you have only 50v but thats only possible if the Pfc is dead. Ips20 will be in standby 120v float on the Led connector no lower then boosted to 160 for 40" and 220 for 50" full array its different for edge lit though so if you have 50v your psu is dead. What is the model lf the Tv first ?
      Last edited by ReeceyBurger123; 10-13-2016, 03:02 PM.
      Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

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      • speedypro
        Badcaps Veteran
        • Feb 2013
        • 561
        • United Kingdom

        #4
        Re: Dropping LED voltage on 17IPS20

        Originally posted by ReeceyBurger123
        Your Psu is faulty if you have only 50v but thats only possible if the Pfc is dead. Ips20 will be in standby 120v float on the Led connector no lower then boosted to 160 for 40" and 220 for 50" full array its different for edge lit though so if you have 50v your psu is dead. What is the model lf the Tv first ?
        CELCUS
        Model: dled39167fhd
        Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer

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        • speedypro
          Badcaps Veteran
          • Feb 2013
          • 561
          • United Kingdom

          #5
          Re: Dropping LED voltage on 17IPS20

          Originally posted by Dannyx
          Does this TV turn on AT ALL ?
          TV turns on. Picture shows except backlight. When powers on, backlight comes on and off in a flash.
          Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer

          Comment

          • Alastair E
            Chief Womble
            • Mar 2013
            • 1963
            • U.K.

            #6
            Re: Dropping LED voltage on 17IPS20

            Dead LED in string....

            Strip panel, test LED's.
            TELEFIX

            How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
            http://www.irf.com/technical-info/appnotes/an-1088.pdf
            PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

            Comment

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