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Vestel 17IPS20P dead to repair

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    Vestel 17IPS20P dead to repair

    Hi there,
    I recently got a Philips TV model 40PFL3008h which was 100% dead, no standby led , nothing. I opened up the tv and found a Vestel PSU, model 17IPS20P, which had some problems on it.
    First here's the picture of the board:


    it's picture from google, and in my case, it's my picture:


    So i annoted all the important things. I had the input fuse FS100 blown which i replaced and 2 diodes D112 and D115 shorted which i replaced. I tried to start the TV but still nothing, no voltage on the secondary side of the SMPS. I then discovered i had a cut track on the other side of the board. So i did bridge at those points, as you can see here:

    I then tried to start the TV, but still no luck. That's where i am now. I make this topic if someone can help me to progress further.
    Here's the schematics pdf:
    http://wikisend.com/download/353380/...20p-r5_sch.pdf
    Thank you.

    #2
    Re: Vestel 17IPS20P dead to repair

    Check the mosfets under the heatsinks for shorts.

    Comment


      #3
      Re: Vestel 17IPS20P dead to repair

      Originally posted by diif View Post
      Check the mosfets under the heatsinks for shorts.
      Ok i've already tested Q301 (unsoldered) and it's good. I'm currently testing Q211 unsoldered (which is not easy to remove).
      I got in diode mode 0.185 between drain and source (COM black probe on drain and red probe on source), not sure it's normal. If i charge the mosfet i have 1.48v between drain and source (drain red probe and source black probe). It should be 0 right?
      I've tested with my component tester, it gives me this:

      datasheet:
      http://pdf1.datasheet.su/fairchild%2.../fqpf8n60c.pdf

      Comment


        #4
        Re: Vestel 17IPS20P dead to repair

        What about what's under the other two heatsinks ?

        Comment


          #5
          Re: Vestel 17IPS20P dead to repair

          Originally posted by diif View Post
          What about what's under the other two heatsinks ?
          I've removed the 3 mosfets with heatsink and tested them and they look ok with my tester and not shorted.
          The mosfet Q100:

          The mosfet Q301:


          I got infinite resistance between +5V_STBY and GROUND, is this normal?
          R299 resistor i get 7.9 Mohm
          Last edited by int0x13; 11-15-2017, 05:36 AM.

          Comment


            #6
            Re: Vestel 17IPS20P dead to repair

            Thinking again and looking at the burn trace on the bottom, check the PWM controller U202 on the bottom and the SMD components leading to it.

            Comment


              #7
              Re: Vestel 17IPS20P dead to repair

              Originally posted by diif View Post
              Thinking again and looking at the burn trace on the bottom, check the PWM controller U202 on the bottom and the SMD components leading to it.
              Ok some progress.
              I got a short beween ground pin and gate pin on the PWM controller (with Q211 removed). And same with the mosfet connected to it. I added annote to my previous picture:

              Now i'll remove this PWM controller and see if i still got a short.

              Update:
              i removed the PWM controller and i have no more short. During the remove i've seen the PCB doing a little "bump" around the IC, strange. I thought it would be because of the big chemical caps on the other side so i've removed them.
              Anyways, now i need to get one PWM controller to replace this one, which is probably dead, i got 8 ohm between GATE and GROUND of the chip (off circuit).
              The original chip is this one https://cdn.badcaps-static.com/pdfs/...4a9fd46ac4.pdf
              I can replace it with equivalent one?
              Last edited by int0x13; 11-15-2017, 12:29 PM.

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