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Philips 47PFL5704D F7 No Power

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    #21
    Re: Philips 47PFL5704D F7 No Power

    The voltage on pin 5 leads me to suspect the diode on the tertiary winding or the Vcc cap is shorted. As momaka said, this is a VERY simple circuit.

    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

      #22
      Re: Philips 47PFL5704D F7 No Power

      Could also be an open resistor in the charging circuit.
      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

        #23
        Re: Philips 47PFL5704D F7 No Power

        Originally posted by tom66 View Post
        Could also be an open resistor in the charging circuit.
        Resistor R104 was showing 194k ohms before I replaced the chip now it shows about 33. k ohms with the new chip in.

        R104 -- 196k ohms

        All the above testing was done in circuit as well.

        Comment

          #24
          Re: Philips 47PFL5704D F7 No Power

          Originally posted by tom66 View Post
          Could also be an open resistor in the charging circuit.
          I don't think so. 'resistor in the charging circuit' is ambiguous, there are two possible meanings. There is a high value resistor from the filtered mains voltage to pin 8. Given the reading at pin 8, that resistor is good. While it is not shown in the app note, there often is a series resistor in the tertiary winding - diode - Vcc cap circuit. If that resistor were open, the smps would start, then die as Vcc dropped below the threshold.

          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

            #25
            Re: Philips 47PFL5704D F7 No Power

            Question....can I test the caps and diodes for shorts while in the circuit or should I just pull them out and test them?

            Comment

              #26
              Re: Philips 47PFL5704D F7 No Power

              Originally posted by kolpro View Post
              Question....can I test the caps and diodes for shorts while in the circuit or should I just pull them out and test them?
              You can test them in the circuit. If you get ambiguous results (a diode that shows 1K in both directions), it should be removed and tested. If you get a low resistance (less than 200 ohms) across a cap, SOMETHING is shorted and causing problems.

              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

                #27
                Re: Philips 47PFL5704D F7 No Power

                Check D107 and C121 out of circuit.
                D107 should show a reading only in the forward direction under diode test (i.e. red probe on anode and black probe on cathode (cathode is the side marked with a white stripe)).
                C121 should go open-circuit after holding the probes on it for a second or two.
                If those components are fine, measure the resistance between pin 5 (Vcc) and pins 1/2 (hot GND).
                Last edited by momaka; 01-10-2012, 10:54 PM.

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                  #28
                  Re: Philips 47PFL5704D F7 No Power

                  D107 is showing .452 and 0L in reverse
                  C121 has a reading for about 1 or 2 seconds then go to 0

                  The resistance between pin 5 and 1 is 15.5k

                  I blew the fuse (6.3ah 250vp) when I hooked it back up today to test for voltage I'm wondering if I can get one from radio shack?
                  Should I put these components back in?
                  Last edited by kolpro; 01-11-2012, 12:18 AM.

                  Comment

                    #29
                    Re: Philips 47PFL5704D F7 No Power

                    Originally posted by kolpro View Post
                    D107 is showing .452 and 0 in reverse
                    Is that 0 or 0L on your multimeter? It makes a big difference.
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                      #30
                      Re: Philips 47PFL5704D F7 No Power

                      Originally posted by retiredcaps View Post
                      Is that 0 or 0L on your multimeter? It makes a big difference.
                      Sorry it goes to .0L on the meter when I test it with the diode tester on my fluke....did I test it correctly?

                      Comment

                        #31
                        Re: Philips 47PFL5704D F7 No Power

                        Originally posted by kolpro View Post
                        Sorry it goes to .0L on the meter when I test it with the diode tester on my fluke....did I test it correctly?
                        Yes, but lately a lot of people haven't been reporting what they see on their multimeter because they don't know how to interpret it.

                        a) 0L on an autorange multimeter means open loop or infinitiy or out of range.

                        b) 0.0 is a unit of measure.

                        c) On manual range meters, "1" on the left hand side means the same as 0L.

                        d) Some people report "no reading" when they see "1" on the left hand side. This is easily the #1 mistake.

                        e) Some people report the quantity, but not what they are measuring (volts, ohms, etc).

                        f) Some people report 1.00 ohm, but it is really 1K ohm, because they forget their dial is set on 2K.

                        PS. Your diode is good. If you had reported 0 (zero), then it would be bad.
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                          #32
                          Re: Philips 47PFL5704D F7 No Power

                          Originally posted by retiredcaps View Post
                          Yes, but lately a lot of people haven't been reporting what they see on their multimeter because they don't know how to interpret it.

                          a) 0L on an autorange multimeter means open loop or infinitiy or out of range.

                          b) 0.0 is a unit of measure.

                          c) On manual range meters, "1" on the left hand side means the same as 0L.

                          d) Some people report "no reading" when they see "1" on the left hand side. This is easily the #1 mistake.

                          e) Some people report the quantity, but not what they are measuring (volts, ohms, etc).

                          f) Some people report 1.00 ohm, but it is really 1K ohm, because they forget their dial is set on 2K.

                          PS. Your diode is good. If you had reported 0 (zero), then it would be bad.
                          I have an auto range meter and now I see what your saying...thanks for the tip.

                          So both seem to be good I assume....

                          Comment

                            #33
                            Re: Philips 47PFL5704D F7 No Power

                            Originally posted by kolpro View Post
                            on my fluke
                            Does you Fluke measure capacitance? If yes, measure C121 and see if it matches the sleeve value.
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                              #34
                              Re: Philips 47PFL5704D F7 No Power

                              Originally posted by retiredcaps View Post
                              Does you Fluke measure capacitance? If yes, measure C121 and see if it matches the sleeve value.
                              This one is s Fluke 75 series 2 Multimeter as no cap tester function on it. I tested the cap with the diode tester function and got those results are they good results?

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                                #35
                                Re: Philips 47PFL5704D F7 No Power

                                Originally posted by kolpro View Post
                                I tested the cap with the diode tester function and got those results are they good results?
                                Inconclusive. For example, a 1000uF cap might only be 680uF, but test "good" on a resistance test.
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