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    Planar PL1700M-BK

    I picked up this monitor for free. When it's plugged in the power light comes on and that's it, the power button doesn't turn it off (have to unplug). I don't get a flash from the backlights and there is no image even with a flashlight. I replaced all the caps on the power/inverter board, checked the fuse its ok.

    Voltages from power board, there is nothing on the board that say what they're for.
    Pin 1 – 10, looking at picture 10 is the top
    1 – 5.15
    2 – 0
    3 – 0
    4 – 0
    5 – 0.3
    6 – 0
    7 – 0.07
    8 – 5.14
    9 – 5.14
    10 – 5.14
    Should there 12V somewhere?

    Also checked the voltage regulators on the logic card
    U10 pin 1 – 5.13, pin 2 – 3.29, pin 3 – 0
    U11 pin 1 – 3.8, pin 2 – 1.8, pin 3 – 0

    I even checked the power button, it has 3.53v to it and when I push it, it goes to 0

    I don't know what to check next, looks to me like the problem is somewhere on the logic card?
    Attached Files

    #2
    Re: Planar PL1700M-BK

    Originally posted by De3rcr View Post
    I picked up this monitor for free. When it's plugged in the power light comes on and that's it, the power button doesn't turn it off (have to unplug). I don't get a flash from the backlights and there is no image even with a flashlight. I replaced all the caps on the power/inverter board, checked the fuse its ok.

    Voltages from power board, there is nothing on the board that say what they're for.
    Pin 1 – 10, looking at picture 10 is the top
    1 – 5.15
    2 – 0
    3 – 0
    4 – 0
    5 – 0.3
    6 – 0
    7 – 0.07
    8 – 5.14
    9 – 5.14
    10 – 5.14
    Should there 12V somewhere?

    Also checked the voltage regulators on the logic card
    U10 pin 1 – 5.13, pin 2 – 3.29, pin 3 – 0
    U11 pin 1 – 3.8, pin 2 – 1.8, pin 3 – 0

    I even checked the power button, it has 3.53v to it and when I push it, it goes to 0

    I don't know what to check next, looks to me like the problem is somewhere on the logic card?
    Most likely on the signal (logic) card. What is the part number of U7, (lower right corner of the Novatek chip)?

    PlainBill
    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

    Comment


      #3
      Re: Planar PL1700M-BK

      U7 is
      AC3NP
      037C9

      I googled it and think I got the datasheet. I can't upload the pdf

      http://www.alldatasheet.com/view.jsp...L431APUN(AC3NP)

      Getting 2.49v on the two legs and 0v on the single side
      Last edited by De3rcr; 02-11-2011, 01:53 PM.

      Comment


        #4
        Re: Planar PL1700M-BK

        The TL431 is supposed to deliver 2.5 volts. Move on. Yes there should be 12v somewhere and it's missing.
        Originally posted by PeteS in CA
        Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
        A working TV? How boring!

        Comment


          #5
          Re: Planar PL1700M-BK

          Originally posted by De3rcr View Post
          Should there 12V somewhere?
          For the missing 12V, try disconnecting everything from the power board and remeasure the voltages at the connector.

          If the 12V is still missing, then measure the DC V at the middle pin of the dual diode (just above C800 in your excellent clear focused pics).
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            #6
            Re: Planar PL1700M-BK

            Originally posted by retiredcaps View Post
            For the missing 12V, try disconnecting everything from the power board and remeasure the voltages at the connector.

            If the 12V is still missing, then measure the DC V at the middle pin of the dual diode (just above C800 in your excellent clear focused pics).
            OK, with everything disconnected from the power supply board and the white wire being the top

            5.21
            5.21
            5.21
            0
            0
            1.66
            0
            0
            0
            5.21

            and I get 15.68v on the middle leg of the dual diode

            Comment


              #7
              Re: Planar PL1700M-BK

              Originally posted by De3rcr View Post
              and I get 15.68v on the middle leg of the dual diode
              Which means the 12v rail is getting lost somewhere before the connector. Look for damaged traces, cracked joints and burnt resistors. Trace the path from the diode and see where it stops.
              Originally posted by PeteS in CA
              Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
              A working TV? How boring!

              Comment


                #8
                Re: Planar PL1700M-BK

                Originally posted by De3rcr View Post
                and I get 15.68v on the middle leg of the dual diode
                Okay, just right of R821 are two diodes. Test them "in circuit" with your multimeter on diode test functionality.

                They should read 0.3 to 0.7V in one direction and 0L or "1" in the other direction. Report both directions for both diodes.

                There are also 4 resistors in the upper right area. You may want to measure the ohms to see if they match their rated capacity.
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                  #9
                  Re: Planar PL1700M-BK

                  Also for the new caps that you replaced in the upper right hand section, see if the 15.68V DC from the dual diode are present across the capacitors. I count 6 of them in that area.
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                    #10
                    Re: Planar PL1700M-BK

                    Originally posted by Th3_uN1Qu3 View Post
                    Which means the 12v rail is getting lost somewhere before the connector. Look for damaged traces, cracked joints and burnt resistors. Trace the path from the diode and see where it stops.
                    You are making an unwarranted assumption. Many designs only send 5V to the signal card; the 12V is used only by the inverter. Looking at the circuit board, it doesn't appear that 12V goes to the connector.

                    PlainBill
                    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                    Comment


                      #11
                      Re: Planar PL1700M-BK

                      I typed in VP-761 into the search engine and found that Acer's 1916 uses the same looking power board (from what I can tell in the photos).

                      I found a service manual and the schematic on page 66 may help.

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                        #12
                        Re: Planar PL1700M-BK

                        Originally posted by retiredcaps View Post
                        Okay, just right of R821 are two diodes. Test them "in circuit" with your multimeter on diode test functionality.

                        They should read 0.3 to 0.7V in one direction and 0L or "1" in the other direction. Report both directions for both diodes.

                        There are also 4 resistors in the upper right area. You may want to measure the ohms to see if they match their rated capacity.
                        The diodes both read .143 in both directions on the diode test and I get 5.21v on the side where the line is.

                        checking the resistors

                        Comment


                          #13
                          Re: Planar PL1700M-BK

                          Originally posted by De3rcr View Post
                          The diodes both read .143 in both directions
                          Lift them from the PCB and test again. If they still test like that they're bad.
                          Originally posted by PeteS in CA
                          Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                          A working TV? How boring!

                          Comment


                            #14
                            Re: Planar PL1700M-BK

                            Originally posted by retiredcaps View Post
                            Also for the new caps that you replaced in the upper right hand section, see if the 15.68V DC from the dual diode are present across the capacitors. I count 6 of them in that area.
                            Getting 15.68 on 3 and 5.21 on 3(see pic)

                            Originally posted by Th3_uN1Qu3 View Post
                            Lift them from the PCB and test again. If they still test like that they're bad.
                            took them out and one is .445 and 1 the other is .456 and 1

                            Comment


                              #15
                              Re: Planar PL1700M-BK

                              oops didn't attach pic
                              Attached Files

                              Comment


                                #16
                                Re: Planar PL1700M-BK

                                Hmm, all the voltages on the caps look okay and it appears the inverter is getting its 12V DC (when loaded).

                                For whatever reason, the logic card is not telling the power/inverter to turn on via some signal (probably 3V DC on the connector??).
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                                  #17
                                  Re: Planar PL1700M-BK

                                  Hmm, I forgot you have another Planar. Looking at the pics, the logic board is different, but maybe open up the working one and figure out which of the 10 pins is the on/off signal. I believe that connector pin will measure 3V DC.

                                  Once the on/off signal pin is determined on the good one, maybe you can "backtrace" the circuit and figure out where the voltage is disappearing on the bad one? This assumes the connector pins are laid out the same way.

                                  Hopefully, that is clear?
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                                  Please do not post inline and offsite as they slow down the loading of pages.

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                                  Comment


                                    #18
                                    Re: Planar PL1700M-BK

                                    Nice photos! How about testing the 4 mosfets, Q904-Q906 for shorts? They are located in a cluster on the bottom of the board. Usually, there's a fuse that blows if one of these mosfets shorts, but it look like there's no fuse for the inverter section.

                                    Comment


                                      #19
                                      Re: Planar PL1700M-BK

                                      Originally posted by retiredcaps View Post
                                      Hmm, I forgot you have another Planar. Looking at the pics, the logic board is different, but maybe open up the working one and figure out which of the 10 pins is the on/off signal. I believe that connector pin will measure 3V DC.

                                      Once the on/off signal pin is determined on the good one, maybe you can "backtrace" the circuit and figure out where the voltage is disappearing on the bad one? This assumes the connector pins are laid out the same way.

                                      Hopefully, that is clear?
                                      The logic board from the other one worked in this one. It powered up, the backlights came on and the osd was displayed, then it went into standby(Works normal). So I took voltages at the connector from the power board while pressing the power button.
                                      Here is what I got from the top pin down

                                      5.17v when off then down to 5.02 when power on then up to 5.22 then to5.17
                                      0v when off and 0 when on
                                      0v when off and 0 when on
                                      0v when off and 0 when on
                                      1.33v when off then 1.28 on then to 1.33
                                      0v when off and 0 when on
                                      0.05 when off then 5.15 when on then back down(standby)
                                      5.17 when off then 5.17 on
                                      5.17 when off then 5.17 on
                                      5.17 when off then 4.99 on then back up to 5.17

                                      Comment


                                        #20
                                        Re: Planar PL1700M-BK

                                        Originally posted by jetadm123 View Post
                                        Nice photos! How about testing the 4 mosfets, Q904-Q906 for shorts? They are located in a cluster on the bottom of the board. Usually, there's a fuse that blows if one of these mosfets shorts, but it look like there's no fuse for the inverter section.
                                        looks like the power board is fine. I'm trying to find the power on from the logic card. I think it's the 0.05 pin(am I right)?

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