Sinotec STL-55D2000 VLED SOLVED

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  • Grunder
    Badcaps Veteran
    • Jan 2016
    • 323
    • south africa

    #1

    Sinotec STL-55D2000 VLED SOLVED

    Hi Everybody,

    This set came in with the 2 secs to black fault. I managed to get the backlights going again by replacing two of the faulty leds with a 9v1 zener diode. (guessing this would deal with 2x 4.5v across these two leds)

    Photo 001 shows the faulty leds.
    I cleaned around the leds to get solder flowing, & had to use a 100w Iron, as the heatsink gobbles up heat making soldering difficult.

    Photo 002 shows the leds removed, & prepared for repair.
    Unfortunately not a clear photo.

    Photo 003 shows the 9v1 zener (revese bias of course) soldered in place making sure not to touch the other print on the pcb. I used double sided tape on the frame so as the zener wouldnt short there either.

    The double sided tape came with a kit of leds I had bought for another repair and didn't use. Hoping that it would deal with any heat generated by the leds. (the leds got very hot whilst testing with the led pcb not secured to the heat sink.)

    Photo 004 shows the lamp house sealed & working, just short of replacing the LCD film/ layer, and closing up.

    Photo 005 all done and ready for collection.

    PS. I'm not sure if the 9v1 zener will handle the current. the set has run for an hour so far, and looks like only time will tell if it can??

    Could one of the more elucidated members please comment on the zeners ability here? (shucks I don't want to open this set again)
    Attached Files
  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #2
    Re: Sinotec STL-55D2000 VLED SOLVED

    If 200mA is flowing through those LEDs, then the zener is dissipating approx power 9.1 * 0.2 = 1.82 watts.

    That is too much for that small zener, so it is likely to fail.

    The max power rating for a glass packaged zener like that will not be more than 0.5 watts, so maximum current will be 54mA. That is pretty low for a string of LEDs like that.

    If you know the total strip voltage and the typical power consumption of the TV, you can make an estimate. Or you can measure the current by using an ammeter.

    A resistor would be a better choice in place of the zener.
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

    Comment

    • Grunder
      Badcaps Veteran
      • Jan 2016
      • 323
      • south africa

      #3
      Re: Sinotec STL-55D2000 VLED SOLVED

      Thanks Tom, I'll only have myself to blame when the set comes back. it was a bugger to open. thanks again.

      Comment

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