DP40142 Power Supply

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  • RAMSELECTRONICS
    ATARI boy
    • Jul 2015
    • 48
    • USA

    #1

    DP40142 Power Supply


    I have a board of power supply part number FSP140-4F01 for LCD TV model DP40142.

    It has 5V, 12V, and 24V output. The issue is 12V and 24V is dead but 5V is working.

    You can see schematic: See page 51



    I replaced on U101 SSC9512S as new, also checked on 2 MOSFET Q101 and Q102 looks good. but I suspected the PC101 does not activated but the chip is good.

    I have no luck also I unable to find the waveform for the SSC9512S.

    need help. THANKS!!
  • CapLeaker
    Leaking Member
    • Dec 2014
    • 8036
    • Canada

    #2
    Re: DP40142 Power Supply

    Did you "force" the PSU on with a couple of resistors or did you just put the PSU back into the TV and truned the TV on?

    Comment

    • RAMSELECTRONICS
      ATARI boy
      • Jul 2015
      • 48
      • USA

      #3
      Re: DP40142 Power Supply

      using TV power on.

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: DP40142 Power Supply

        If PWR (PS-ON, >2.5VDC = ON) is not present then you will not have 12V/24V. So check and see if you do have PWR (PS-ON) connector P802 pin 13 signal from the main board.
        Attached Files
        Last edited by budm; 07-13-2015, 10:31 AM.
        Never stop learning
        Basic LCD TV and Monitor troubleshooting guides.
        http://www.badcaps.net/forum/showthr...956#post305956

        Voltage Regulator (LDO) testing:
        http://www.badcaps.net/forum/showthr...999#post300999

        Inverter testing using old CFL:
        http://www.badcaps.net/forum/showthr...er+testing+cfl

        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
        http://s807.photobucket.com/user/budm/library/

        TV Factory reset codes listing:
        http://www.badcaps.net/forum/showthread.php?t=24809

        Comment

        • RAMSELECTRONICS
          ATARI boy
          • Jul 2015
          • 48
          • USA

          #5
          Re: DP40142 Power Supply

          ok
          Last edited by RAMSELECTRONICS; 07-13-2015, 10:36 AM.

          Comment

          • RAMSELECTRONICS
            ATARI boy
            • Jul 2015
            • 48
            • USA

            #6
            Re: DP40142 Power Supply

            Ok, Will check it out.
            THANKS!

            Comment

            • RAMSELECTRONICS
              ATARI boy
              • Jul 2015
              • 48
              • USA

              #7
              Re: DP40142 Power Supply

              I checked the voltmeter said 3.4V.

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: DP40142 Power Supply

                Good, so now you will need to check the DCV in the 12V/24V power supply section, start by verifying that you do have VCC to run the SMPS IC U101, check the DCV between pin 2 (VCC) and PIN 4 (SGND).
                What is the P/N as printed on top of that U101?
                Never stop learning
                Basic LCD TV and Monitor troubleshooting guides.
                http://www.badcaps.net/forum/showthr...956#post305956

                Voltage Regulator (LDO) testing:
                http://www.badcaps.net/forum/showthr...999#post300999

                Inverter testing using old CFL:
                http://www.badcaps.net/forum/showthr...er+testing+cfl

                Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                http://s807.photobucket.com/user/budm/library/

                TV Factory reset codes listing:
                http://www.badcaps.net/forum/showthread.php?t=24809

                Comment

                • RAMSELECTRONICS
                  ATARI boy
                  • Jul 2015
                  • 48
                  • USA

                  #9
                  Re: DP40142 Power Supply

                  U101 I posted at the first. see scroll up there is p/n
                  it say SSC9512S

                  Comment

                  • RAMSELECTRONICS
                    ATARI boy
                    • Jul 2015
                    • 48
                    • USA

                    #10
                    Re: DP40142 Power Supply

                    I check on pin 4 now

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA

                      #11
                      Re: DP40142 Power Supply

                      Originally posted by RAMSELECTRONICS
                      I check on pin 4 now
                      DCV between pin 2 (VCC) and pin 4 (GND, PRIMARY SIDE circuit GND).
                      Never stop learning
                      Basic LCD TV and Monitor troubleshooting guides.
                      http://www.badcaps.net/forum/showthr...956#post305956

                      Voltage Regulator (LDO) testing:
                      http://www.badcaps.net/forum/showthr...999#post300999

                      Inverter testing using old CFL:
                      http://www.badcaps.net/forum/showthr...er+testing+cfl

                      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                      http://s807.photobucket.com/user/budm/library/

                      TV Factory reset codes listing:
                      http://www.badcaps.net/forum/showthread.php?t=24809

                      Comment

                      • RAMSELECTRONICS
                        ATARI boy
                        • Jul 2015
                        • 48
                        • USA

                        #12
                        Re: DP40142 Power Supply

                        Here I use oscilloscope:

                        PIN 2:




                        PIN 4:

                        Comment

                        • budm
                          Badcaps Legend
                          • Feb 2010
                          • 40746
                          • USA

                          #13
                          Re: DP40142 Power Supply

                          You use the scope to directly measuring the Voltage on the HOT PRIMARY side of the circuit?
                          It looks to me you are using the chassis for your scope probe that is why you are seeing such a large AC signal.
                          To use the scope in the primary side, you MUST is Isolation transformer on the unit you are working on, the GND ref for the primary is the negative leg of the main filter cap, so DO NOT ATTACH THE SCOPE GND probe to anything in the primary side of the circuit!
                          Why don't you just use the DMM to measure the VCC of that IC?
                          Last edited by budm; 07-13-2015, 12:51 PM.
                          Never stop learning
                          Basic LCD TV and Monitor troubleshooting guides.
                          http://www.badcaps.net/forum/showthr...956#post305956

                          Voltage Regulator (LDO) testing:
                          http://www.badcaps.net/forum/showthr...999#post300999

                          Inverter testing using old CFL:
                          http://www.badcaps.net/forum/showthr...er+testing+cfl

                          Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                          http://s807.photobucket.com/user/budm/library/

                          TV Factory reset codes listing:
                          http://www.badcaps.net/forum/showthread.php?t=24809

                          Comment

                          • RAMSELECTRONICS
                            ATARI boy
                            • Jul 2015
                            • 48
                            • USA

                            #14
                            Re: DP40142 Power Supply

                            Shoot. what's wrong my brain! I will use isolate transformer for the oscilloscope to use gnd and vcc. be back.

                            Comment

                            • budm
                              Badcaps Legend
                              • Feb 2010
                              • 40746
                              • USA

                              #15
                              Re: DP40142 Power Supply

                              Originally posted by RAMSELECTRONICS
                              Shoot. what's wrong my brain! I will use isolate transformer for the oscilloscope to use gnd and vcc. be back.
                              Not on the scope, you use it on the unit you are working on and you must make sure that it is true isolation transformer, the Neutral should not be tied to the ground prong of the AC outlet of the isolation transformer.
                              Never stop learning
                              Basic LCD TV and Monitor troubleshooting guides.
                              http://www.badcaps.net/forum/showthr...956#post305956

                              Voltage Regulator (LDO) testing:
                              http://www.badcaps.net/forum/showthr...999#post300999

                              Inverter testing using old CFL:
                              http://www.badcaps.net/forum/showthr...er+testing+cfl

                              Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                              http://s807.photobucket.com/user/budm/library/

                              TV Factory reset codes listing:
                              http://www.badcaps.net/forum/showthread.php?t=24809

                              Comment

                              • CapLeaker
                                Leaking Member
                                • Dec 2014
                                • 8036
                                • Canada

                                #16
                                Re: DP40142 Power Supply

                                Originally posted by RAMSELECTRONICS
                                Shoot. what's wrong my brain! I will use isolate transformer for the oscilloscope to use gnd and vcc. be back.
                                DON'T DO THAT!
                                That is backwards! You supposed to put the PSU on the isolation transformer. The scope supposed to be connected to your wall socket!

                                Comment

                                • RAMSELECTRONICS
                                  ATARI boy
                                  • Jul 2015
                                  • 48
                                  • USA

                                  #17
                                  Re: DP40142 Power Supply

                                  HA HA... no worries.. I checked with voltmeter VCC pin 2 and GND pin 4 DC is zero, AC is 3.33V.

                                  BUT I look up the schematic the VCC where came from.. I could not find it ummm...

                                  Comment

                                  • RAMSELECTRONICS
                                    ATARI boy
                                    • Jul 2015
                                    • 48
                                    • USA

                                    #18
                                    Re: DP40142 Power Supply

                                    Ummm.. Look the schematic... you see U501 is A6069H is CLICK HERE

                                    I checked voltmeter showing 14.4V out from the VCC pin 5 from U501.
                                    So it connected to Q503 emitter and base showing 15V DC.
                                    The collector is zero voltage.

                                    seem like Q503 is bad? it is VERY small as SMD.

                                    Comment

                                    • RAMSELECTRONICS
                                      ATARI boy
                                      • Jul 2015
                                      • 48
                                      • USA

                                      #19
                                      Re: DP40142 Power Supply

                                      Do you guys think I should try replace with 2N3906?

                                      I unable to read the label on the bad one as no label.
                                      Last edited by RAMSELECTRONICS; 07-13-2015, 06:30 PM.

                                      Comment

                                      • budm
                                        Badcaps Legend
                                        • Feb 2010
                                        • 40746
                                        • USA

                                        #20
                                        Re: DP40142 Power Supply

                                        Originally posted by RAMSELECTRONICS
                                        Ummm.. Look the schematic... you see U501 is A6069H is CLICK HERE

                                        I checked voltmeter showing 14.4V out from the VCC pin 5 from U501.
                                        So it connected to Q503 emitter and base showing 15V DC.
                                        The collector is zero voltage.

                                        seem like Q503 is bad? it is VERY small as SMD.
                                        Q503 PNP Transistor is not turned on.
                                        The Voltage is generated from the AUX winding of the standby power supply transformer T501, the AC is then rectified by D505 and filtered by C509, it is then fed into linear regulator circuit consists of Q504 (NPN)/ZENER ZD503, the regulated output is on the Emitter of Q504 which is fed to Emitter of Q503 (PNP), for Q503 to be turned on, the Base Voltage will have to be 0.6~0.7V LOWER than the Voltage at the Emitter of Q503, this is done by turning on OPTO PC502, the PC 502 is turned on when Q203 is turned on by the PS_ON signal.
                                        So you need to check the BASE Voltage OF Q503, it must be 0.6~0.7VDC less than the Emitter Voltage, if it is not then the opto or Q203 is not working.
                                        Also the resistance between VCC (2) and GND (4) PIN of the IC to make sure it does not show low resistance.
                                        BTW, you did change C509, right?
                                        Last edited by budm; 07-13-2015, 07:10 PM.
                                        Never stop learning
                                        Basic LCD TV and Monitor troubleshooting guides.
                                        http://www.badcaps.net/forum/showthr...956#post305956

                                        Voltage Regulator (LDO) testing:
                                        http://www.badcaps.net/forum/showthr...999#post300999

                                        Inverter testing using old CFL:
                                        http://www.badcaps.net/forum/showthr...er+testing+cfl

                                        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                                        http://s807.photobucket.com/user/budm/library/

                                        TV Factory reset codes listing:
                                        http://www.badcaps.net/forum/showthread.php?t=24809

                                        Comment

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