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PRIMA LCD 32" TV clicking on off

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    #1

    PRIMA LCD 32" TV clicking on off

    I picked up this tv today.

    The power supply board have this reference L32W19-20.
    When I push the power button the screen turn on and off very fast because it clicks on and off quickly. (the backlight turn on and off very fast repeately).

    There was a visible blown capacitor which I changed.
    Near of this capacitor, there is a 3W resistor which have symptoms of overheating and the colors are not distinguishable. This resistor measure 450ohms but I think it should be 1K.
    I measured the output of the connectors and it output +5VDC in standby but when I turn on I don't see any other voltage than +5VDC.

    Any advice what to check on the power supply board?
    Attached Files
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    #2
    Re: PRIMA LCD 32" TV clicking on off

    Check F0502, it is just barely visible in your second picture.

    Also, replace the rest of the capacitors. The 'TL' and 'JH' ones are crap! Is that Daewoo capacitor the new one? And is it low-esr? I sugguest using somthing better like panasonic or nichicon capacitors.
    Last edited by ben7; 08-14-2013, 06:10 AM.
    Muh-soggy-knee

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      #3
      Re: PRIMA LCD 32" TV clicking on off

      With any rapid backlight flickering problems, I always check the voltage across the large 450V capacitor.
      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.

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        #4
        Re: PRIMA LCD 32" TV clicking on off

        I have checked continuity on FU502 and FU503 (first picture) and both are ok.
        Yes, the Daewoo capacitor is the new one. (Daewoo RMU Series 105º Standard).
        I bought these capacitors at the local electronics store. Let me know if these are ok.

        How can I safely check the voltage across the high voltage capacitor?
        The 3W resistor should be changed?

        Thanks.
        Last edited by pyrosster; 08-14-2013, 07:53 AM.

        Comment

          #5
          Re: PRIMA LCD 32" TV clicking on off

          The Daewoo is probably not suitable, the RMU series is not low impedance and will likely fail


          Testing the voltage across the 450V cap is done with two probes and two steady hands. If you slip, you will get a loud bang and blow the mains fuse or trip the main circuit breaker, but other stuff will probably survive... Just be careful.
          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.

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            #6
            Re: PRIMA LCD 32" TV clicking on off

            I have tested the voltage across the 450V capacitor and is ok too. The power supply continue to click on and off and the backlight turn on and off.
            I see a IC with the reference CP1002PN (with Power Integrations Logo). How could I check this IC?

            Thanks again.

            Comment

              #7
              Re: PRIMA LCD 32" TV clicking on off

              When you say the voltage across the 450V capacitor is "OK" what do you mean?
              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.

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                #8
                Re: PRIMA LCD 32" TV clicking on off

                I checked again across the big capacitor and show 375 volts, this is normal? I used DVM at the 600VDC scale.
                The capacitor dont show bulging at the top.
                Last edited by pyrosster; 08-21-2013, 09:47 AM.

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                  #9
                  Re: PRIMA LCD 32" TV clicking on off

                  I checked output voltages and I see 22VDC, 13VDC and 1.5VDC. The 1.5V is normal?

                  Comment

                    #10
                    Re: PRIMA LCD 32" TV clicking on off

                    375V is OK, but is it stable as the screen flickers?
                    Where, which pin, are you measuring the 1.5V DC?
                    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

                      #11
                      Re: PRIMA LCD 32" TV clicking on off

                      Today I measured big capacitor voltages again and it show between 355V - 358V DC.
                      I post some pictures where I'm measuring these voltages.
                      what can I do?

                      Thanks.
                      Attached Files

                      Comment

                        #12
                        Re: PRIMA LCD 32" TV clicking on off

                        Fixed link: (The link is a 404, because it's malformed.)

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                          #13
                          Re: PRIMA LCD 32" TV clicking on off

                          355 to 358V is too low. Can you check what your local AC mains voltage is?
                          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.

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                            #14
                            Re: PRIMA LCD 32" TV clicking on off

                            local AC mains voltage is 235V AC.

                            Comment

                              #15
                              Re: PRIMA LCD 32" TV clicking on off

                              Check the voltage across this capacitor.
                              Attached Files
                              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

                                #16
                                Re: PRIMA LCD 32" TV clicking on off

                                the voltage across the capacitor is 13V DC

                                Comment

                                  #17
                                  Re: PRIMA LCD 32" TV clicking on off

                                  Does it fluctuate, or is it steady?
                                  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.

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                                    #18
                                    Re: PRIMA LCD 32" TV clicking on off

                                    I'm measuring voltage again and dont give any reading. only 0.02 volts and fluctuate.

                                    Comment

                                      #19
                                      Re: PRIMA LCD 32" TV clicking on off

                                      I'm confused, are you saying it's fluctuating by 0.02V, or is only 0.02V now? Is clicking on and off still happening or not?
                                      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

                                        #20
                                        Re: PRIMA LCD 32" TV clicking on off

                                        yes. yesterday I measured 13V DC and fluctuating +-0.3V DC. Today I'm measuring the same capacitor and dont give any reading, only 0.02V DC.
                                        The clicking on and off is still happening.

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