when i turn on, Philliips TV is not on

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  • Nish
    Senior Member
    • Sep 2013
    • 124
    • Canada

    #141
    Re: when i turn on, Philliips TV is not on

    I put 1k resistor to connect P-ON-H1 to AL+5V.

    Now reading

    C912 = 13.40
    C906 = 18.96
    C951A = 5.56

    Across ZD907 = 1.30

    No voltage at output of IC902
    Last edited by Nish; 02-07-2020, 11:58 AM.

    Comment

    • R_J
      Badcaps Legend
      • Jun 2012
      • 9535
      • Canada

      #142
      Re: when i turn on, Philliips TV is not on

      When you add the 1k to turn on the power supply, does the voltage on ic902, pin1 change? this is the ENable pin for the regulator, If it is changing (logic high) and you still have no output from ic902, either the ic is bad or there is a short on the output. If the ouput voltage is 0 volts I would suspect the ic, if there is 1~2 volts, It could be too high a load. as ic801 and ic601 have 10Ω resistors in there VCC lines.

      Comment

      • Nish
        Senior Member
        • Sep 2013
        • 124
        • Canada

        #143
        Re: when i turn on, Philliips TV is not on

        Before install 1k resistor
        PC902
        Pin4 = 16.22
        Pin3 = 15.55
        C906 = 16.20

        After 1k resistor install
        PC902
        Pin4 = 19
        Pin3 = 18.55
        C906 = 19

        Output voltage of IC902 = 0.053v and goes to 0v right away.

        Comment

        • R_J
          Badcaps Legend
          • Jun 2012
          • 9535
          • Canada

          #144
          Re: when i turn on, Philliips TV is not on

          Looks like the regulator is bad, It should output around 15~17v when ENable is high.

          Comment

          • Nish
            Senior Member
            • Sep 2013
            • 124
            • Canada

            #145
            Re: when i turn on, Philliips TV is not on

            I try to buy the regulator. I couldn't find this ic. I have attached the picture.
            Attached Files

            Comment

            • R_J
              Badcaps Legend
              • Jun 2012
              • 9535
              • Canada

              #146
              Re: when i turn on, Philliips TV is not on

              You can order them from China. They seem to be a custom part number but are likely made by Texas Instruments, and might be a TPS7A4501DCQR or TL1963ADCQR I have not tried any of these substitutes.
              Last edited by R_J; 02-08-2020, 06:12 PM.

              Comment

              • Nish
                Senior Member
                • Sep 2013
                • 124
                • Canada

                #147
                Re: when i turn on, Philliips TV is not on

                IC902

                Pin4 = 16.42
                Pin5 = 1.27


                IC601 PIN12= 16.24

                Comment

                • R_J
                  Badcaps Legend
                  • Jun 2012
                  • 9535
                  • Canada

                  #148
                  Re: when i turn on, Philliips TV is not on

                  IC601 provides about 17v internally. This is a low current voltage and needs to be suplemented by IC902 for the ic to work.
                  IC902 supplies the VCC voltage for IC801, pin12 and IC601, pin12 and also turns on Q802, which turns on Q800, which tells both IC801 and IC601 to start.

                  I suspect if you replace the regulator ic, the power supply could be close to being fixed.
                  Last edited by R_J; 02-11-2020, 05:12 PM.

                  Comment

                  • Nish
                    Senior Member
                    • Sep 2013
                    • 124
                    • Canada

                    #149
                    Re: when i turn on, Philliips TV is not on

                    IC801 pin12 = 16.18v
                    IC601 pin12 = 16.24v
                    Q802 =0.659v
                    Q800 = 0v

                    I will replace R818 and see
                    Attached Files

                    Comment

                    • R_J
                      Badcaps Legend
                      • Jun 2012
                      • 9535
                      • Canada

                      #150
                      Re: when i turn on, Philliips TV is not on

                      What is the point of replacing R818? Why do you think they have the regulator ic in this circuit?
                      Last edited by R_J; 02-12-2020, 10:59 AM.

                      Comment

                      • Nish
                        Senior Member
                        • Sep 2013
                        • 124
                        • Canada

                        #151
                        Re: when i turn on, Philliips TV is not on

                        When I measure resistance, I did not get resistance. I thought bad resistor.

                        Comment

                        • Nish
                          Senior Member
                          • Sep 2013
                          • 124
                          • Canada

                          #152
                          Re: when i turn on, Philliips TV is not on

                          What should I do?

                          Comment

                          • R_J
                            Badcaps Legend
                            • Jun 2012
                            • 9535
                            • Canada

                            #153
                            Re: when i turn on, Philliips TV is not on

                            Originally posted by Nish
                            What should I do?
                            Replace the regulator ic! The chances of that 10K resistor being bad is next to imposible.

                            Again: Why do you think they have the regulator ic902 in this circuit?
                            Last edited by R_J; 02-12-2020, 12:27 PM.

                            Comment

                            • Nish
                              Senior Member
                              • Sep 2013
                              • 124
                              • Canada

                              #154
                              Re: when i turn on, Philliips TV is not on

                              Originally posted by R_J
                              Replace the regulator ic! The chances of that 10K resistor being bad is next to imposible.

                              Again: Why do you think they have the regulator ic902 in this circuit?
                              To supply voltage to IC801 and IC601. That's what I think.

                              Comment

                              • R_J
                                Badcaps Legend
                                • Jun 2012
                                • 9535
                                • Canada

                                #155
                                Re: when i turn on, Philliips TV is not on

                                Originally posted by Nish
                                To supply voltage to IC801 and IC601. That's what I think.
                                That is correct. So if the INPUT has (19v) and the enable pin is high (18.5v) and the OUTPUT is 0 volts, (and the output line is not shorted to ground) what could be wrong.

                                Comment

                                • Nish
                                  Senior Member
                                  • Sep 2013
                                  • 124
                                  • Canada

                                  #156
                                  Re: when i turn on, Philliips TV is not on

                                  Originally posted by R_J
                                  That is correct. So if the INPUT has (19v) and the enable pin is high (18.5v) and the OUTPUT is 0 volts, (and the output line is not shorted to ground) what could be wrong.
                                  Should be the regulator IC902 is not functioning.


                                  But the IC902 pins are reading the below voltage.

                                  IC902
                                  Pin1 = 2.527v
                                  Pin2 = 19.19v
                                  Pin3 = 0v (gnd)
                                  Pin4 = 16.24v (output)
                                  Pin5 = 1.29v
                                  Pin6 = 0v (gnd)

                                  Is this IC not working? I am confuse.

                                  Comment

                                  • R_J
                                    Badcaps Legend
                                    • Jun 2012
                                    • 9535
                                    • Canada

                                    #157
                                    Re: when i turn on, Philliips TV is not on

                                    Originally posted by Nish
                                    Should be the regulator IC902 is not functioning.


                                    But the IC902 pins are reading the below voltage.

                                    IC902
                                    Pin1 = 2.527v
                                    Pin2 = 19.19v
                                    Pin3 = 0v (gnd)
                                    Pin4 = 16.24v (output)
                                    Pin5 = 1.29v
                                    Pin6 = 0v (gnd)

                                    Is this IC not working? I am confuse.
                                    I was going by what you reported earlier in post# 143
                                    Output voltage of IC902 = 0.053v and goes to 0v right away.
                                    and post#141
                                    No voltage at output of IC902
                                    That is why I suspected the regulator, so it IS working ok.

                                    So you should now have PANEL+24V and P-ON+12V
                                    Last edited by R_J; 02-12-2020, 02:25 PM.

                                    Comment

                                    • Nish
                                      Senior Member
                                      • Sep 2013
                                      • 124
                                      • Canada

                                      #158
                                      Re: when i turn on, Philliips TV is not on

                                      Originally posted by R_J
                                      I was going by what you reported earlier in post# 143 and post#141 That is why I suspected the regulator, so it IS working ok.

                                      So you should now have PANEL+24V and P-ON+12V

                                      Ok sorry about that. I mislead you.


                                      No I do not have PANEL+24V and P-ON+12V at the connector.

                                      I have attached the picture of voltage now.
                                      Attached Files

                                      Comment

                                      • Nish
                                        Senior Member
                                        • Sep 2013
                                        • 124
                                        • Canada

                                        #159
                                        Re: when i turn on, Philliips TV is not on

                                        Is there anything I can check please?

                                        Comment

                                        • R_J
                                          Badcaps Legend
                                          • Jun 2012
                                          • 9535
                                          • Canada

                                          #160
                                          Re: when i turn on, Philliips TV is not on

                                          The only voltage that points to a line is the 350v, That tells be that the pfc circuit and IC801 is working. The 16.24 seems to be the vcc supply, so that is correct. Is the 1.1 volts for pin 4 or pin5 of IC601?
                                          I have no idea where you measured the 87.2
                                          Looks like the IC601 circuit is not working, check the resistance of R618(15Ω), R617(51Ω) and R620(51Ω) and [R52 1](15Ω) If they are ok. Check the voltage on pins 11,14 & 15, Also is there any voltage on D601 cathode?

                                          I looked closer at the connections on T601, The connections on pins 1 & 2 don't look that good, Remove the old solder, clean up the trace and rivet and resolder them
                                          Last edited by R_J; 02-14-2020, 04:17 PM.

                                          Comment

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