Thank you to the guys at HEGE supporting Badcaps [ HEGE ] [ HEGE DEX Chart ]

Announcement

Collapse
No announcement yet.

philips 55pft5500/12 Backlight issue. What am I doing wrong?

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
    #1

    philips 55pft5500/12 Backlight issue. What am I doing wrong?

    TV philips 55'' no backlight (image ok).
    I tested the backlight with my led tester from the unplugged connector cable and it lights up. I had voltages at the motherboard connector, but anyway I order a new psu. Same problem, same voltages. Disassembled the TV and checked every strip with my led tester, they all light up, same voltage for every pair of strip (they go two by two).
    What am I missing?

    And something else I don't understand. I checked and I have 3v Leds, 10 per strips. Why every pair of strip (so 20 Led) take about 32v when powered up with my led tester 🤔
    2 Photos
    Last edited by SMDFlea; 04-17-2024, 12:39 PM. Reason: philips 55pft5500/12
    Tags: None
    #2
    Sometimes main board is culprit. I am not familiar with this TV at all, but I hav seen some tvs backlights not working because of main board. Main board sends signal to turn on BL and it doesn't. What is the legend for the PSU to MB show. One of those pins may be missing voltsge

    Comment

      #3
      Put make and model number in thread title ! ! !
      https://www.badcaps.net/forum/troubl...n-thread-title
      All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

      Comment

        #4
        Sorry. Model: philips 55pft5500/12. I can't edit my title.

        EazyBone I didn't think to check the return signals, assuming everything was alright since the TV worked fine (backlight apart). I'll check the signals, hoping that is a problem, at least I can try to work it out.
        One thing I know for sure. When the TV is in standby I don't have voltage at the BL connector. If I turn on the TV I have it instead.
        When the TV is on I have 76v on the positive lines and 48v at the negative ones, comparing with ground. While checking with my led tester, it takes 125v on the positive lines, if I am not mistaken.

        Comment

          #5
          you need to messure the LED socket... between LED- & LED+ on each Group.. then compare

          Comment

            #6
            Give us a pic of the PSU legend to mb

            Comment

              #7
              Diah oh yeah, I forgot to mention. I don't know why, but if I measure the connector LED + and LED - with my multimeter I don't have a reading (voltage DC mode) but if compare them to ground I have 76v and 48v respectively. If I use my LED tester on the connector (connector disconnected, testing from the Led side of course), LED + and LED -, i have around 30v (if I am not mistaken) and the backlight is fully present.
              EazyBone ok, I upload the pic now.
              If needed, I upload also the schematic of the psu
              Attached Files
              1 Photo

              Comment

                #8
                What does bl/on / dim/ 3d(?)on voltages show when turned on

                Comment

                  #9
                  Check these areas from the back side to see if the tracks are damaged...
                  Attached Files

                  Comment

                    #10
                    Originally posted by DoOm86 View Post
                    Diah oh yeah, I forgot to mention. I don't know why, but if I measure the connector LED + and LED - with my multimeter I don't have a reading (voltage DC mode)
                    this mean there are no signal on pins BL_OFF/ON.... or as Lotas mentioned... you have damage on the track of the left side which its belong to LED BL circuit

                    Comment

                    Previous template Next
                    Working...
                    X