Power suply doesn't work (DPS-214CP)

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  • NoN4me
    Member
    • Jun 2017
    • 20
    • Spain

    #1

    Power suply doesn't work (DPS-214CP)

    Hello,
    I've got a TV wich power supply is a DPS-214CP (schematic attached), and the thing is that it doesn't power on. I dont even get stand by power.

    IC901 (DDA010) has an VCC Votage between 10 and 18 Volts in a triangle wave. It's said in the IC901 datasheet that IC starts up when vcc reachs 18 volts, but in my case Drain pin never starts switching.

    I have checked diodes resistors and caps but I can't find the problem.

    Can anybody lend a hand?
    Thank you in advance.
    Attached Files
    Last edited by NoN4me; 06-01-2017, 04:05 PM.
  • petehall347
    Badcaps Legend
    • Jan 2015
    • 4426
    • United Kingdom

    #2
    Re: Power suply doesn't work (DPS-214CP)

    is b+ good ?

    Comment

    • CapLeaker
      Leaking Member
      • Dec 2014
      • 8065
      • Canada

      #3
      Re: Power suply doesn't work (DPS-214CP)

      maybe a dead pwm. Wouldn't be the first time...

      Comment

      • NoN4me
        Member
        • Jun 2017
        • 20
        • Spain

        #4
        Re: Power suply doesn't work (DPS-214CP)

        Originally posted by petehall347
        is b+ good ?
        Yes, 320 volts


        Originally posted by CapLeaker
        maybe a dead pwm. Wouldn't be the first time...
        The pwm is that DDA010, isn't it? I have replaced it already. Nothing hapened.

        Comment

        • dskall
          Badcaps Legend
          • Oct 2016
          • 2905
          • usa

          #5
          Re: Power suply doesn't work (DPS-214CP)

          optocoupler, feedback voltage?
          I assume no responsibility for any stupid suggestions I might post.

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #6
            Re: Power suply doesn't work (DPS-214CP)

            What did you use for the GND ref. point for your meter or scope when you make the Voltage measurement in that primary side of the circuit?
            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

            • NoN4me
              Member
              • Jun 2017
              • 20
              • Spain

              #7
              Re: Power suply doesn't work (DPS-214CP)

              Originally posted by dskall
              optocoupler, feedback voltage?
              5 volts in FB pin

              Originally posted by budm
              What did you use for the GND ref. point for your meter or scope when you make the Voltage measurement in that primary side of the circuit?
              I put the aligator clip of the scope in the negative pin of the main capacitor.

              Comment

              • NoN4me
                Member
                • Jun 2017
                • 20
                • Spain

                #8
                Re: Power suply doesn't work (DPS-214CP)

                Here you are the measures at the diferent points commented before.
                B+, FB pin, IC Vcc (in this order).
                Attached Files

                Comment

                • dick_barton
                  Badcaps Legend
                  • Aug 2015
                  • 6642
                  • Wales

                  #9
                  Re: Power suply doesn't work (DPS-214CP)

                  VCC is initially supplied via the DDA010 internal current cell until it reaches a specific value after which it switches off. The IC should then start to drive the internal mosfet to switch T901 which will then maintain VCC through the winding (pins 9-10) of T901 which is rectified and connected to VCC and it's charging capacitor C904.

                  If the IC fails to drive T901 for whatever reason, then there is no secondary voltage to maintain VCC. The IC restarts and charges the VCC startup capacitor via it's internal startup circuit once again until it reaches VCCstartup threshold at which point the internal charge circuit switches off.

                  This I believe would explain the ramp that you see on VCC

                  VCC = 18V and internal charge circuit switches off
                  VCC = 10.5V and internal charge circuit switches on

                  Can you scope the Drain (pin 5) and check that the internal mosfet is switching transformer T901

                  I would check R903, D902, C903, C904, D903, Q901, R904, ZD901

                  Out of curiosity are you using an isolation transformer to power up the set or using a scope isolation probe?
                  Last edited by dick_barton; 06-02-2017, 11:35 AM.
                  Willing to help but I'm no expert.

                  Comment

                  • dskall
                    Badcaps Legend
                    • Oct 2016
                    • 2905
                    • usa

                    #10
                    Re: Power suply doesn't work (DPS-214CP)

                    Here is spec sheet for DDA010 http://www.datasheetspdf.com/datasheet/DDA010.html
                    Seems 5v feedback is to high but I am not good with specs so budm or someone can correct. And educate.
                    I assume no responsibility for any stupid suggestions I might post.

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA

                      #11
                      Re: Power suply doesn't work (DPS-214CP)

                      The current sensing resistors on CS pin 3 are good?
                      If leave the scope on Drain pin 5 and nothing else hook up to the board then you apply AC to board, do you see any action at all on the Drain pin for seconds? The rectifier D950 in the cold side is good?
                      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

                      • NoN4me
                        Member
                        • Jun 2017
                        • 20
                        • Spain

                        #12
                        Re: Power suply doesn't work (DPS-214CP)

                        Originally posted by dick_barton
                        Can you scope the Drain (pin 5) and check that the internal mosfet is switching transformer T901

                        I would check R903, D902, C903, C904, D903, Q901, R904, ZD901

                        Out of curiosity are you using an isolation transformer to power up the set or using a scope isolation probe?
                        I have attached a screenshot of the drain pin.
                        Those components that you mentioned are OK.
                        About isolation I'm not using any of them, just being very careful avoiding touch the ground of the scope.


                        Originally posted by budm
                        The current sensing resistors on CS pin 3 are good?
                        If leave the scope on Drain pin 5 and nothing else hook up to the board then you apply AC to board, do you see any action at all on the Drain pin for seconds? The rectifier D950 in the cold side is good?
                        Yes, current sensing reistors are OK and D950 is also OK.
                        I have atached a screenshot of the input pin of the IC902 as well as a screenshot of the behaviour of the drain pin when I apply AC to board.
                        D950 is also OK.
                        Attached Files

                        Comment

                        • dick_barton
                          Badcaps Legend
                          • Aug 2015
                          • 6642
                          • Wales

                          #13
                          Re: Power suply doesn't work (DPS-214CP)

                          It's best practice to use an isolation transformer so that you don't accidentally give yourself a shock. Cheaper than a funeral.
                          Willing to help but I'm no expert.

                          Comment

                          • NoN4me
                            Member
                            • Jun 2017
                            • 20
                            • Spain

                            #14
                            Re: Power suply doesn't work (DPS-214CP)

                            Of course, I know, but I don't have an isolation transformer, I don't usually measure live areas.

                            Comment

                            • dick_barton
                              Badcaps Legend
                              • Aug 2015
                              • 6642
                              • Wales

                              #15
                              Re: Power suply doesn't work (DPS-214CP)

                              So transformer T901 is not being switched.
                              IC902 (IN1) needs 1.8V peak or more and the output (FPO) I think would be around 7V
                              Attached Files
                              Willing to help but I'm no expert.

                              Comment

                              • NoN4me
                                Member
                                • Jun 2017
                                • 20
                                • Spain

                                #16
                                Re: Power suply doesn't work (DPS-214CP)

                                Well, I have to say thay in this case when I measure FPO with the scope I obtain a flat line in 0 volts but when I measure with a multimeter I obtain 5 volts. (I desoldered FPO pin to measure it)
                                Last edited by NoN4me; 06-02-2017, 05:41 PM.

                                Comment

                                • PeteS in CA
                                  Badcaps Legend
                                  • Aug 2005
                                  • 3578
                                  • USA, Unsure of Planet

                                  #17
                                  Re: Power suply doesn't work (DPS-214CP)

                                  Does the FB pin voltage of ~4.5-5V shut down the DDA010?
                                  PeteS in CA

                                  Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
                                  ****************************
                                  To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
                                  ****************************

                                  Comment

                                  • NoN4me
                                    Member
                                    • Jun 2017
                                    • 20
                                    • Spain

                                    #18
                                    Re: Power suply doesn't work (DPS-214CP)

                                    I don't know.

                                    Comment

                                    • dick_barton
                                      Badcaps Legend
                                      • Aug 2015
                                      • 6642
                                      • Wales

                                      #19
                                      Re: Power suply doesn't work (DPS-214CP)

                                      From the data sheet it looks like FPO is Low (0V) when IN1 is between 1.17v --> 1.28V
                                      When IN1 => 1.28V then FPO goes High.

                                      You cannot measure FPO with the pin disconnected since it's an an open Drain connection.
                                      Datasheet post#15
                                      Last edited by dick_barton; 06-03-2017, 08:24 AM.
                                      Willing to help but I'm no expert.

                                      Comment

                                      • NoN4me
                                        Member
                                        • Jun 2017
                                        • 20
                                        • Spain

                                        #20
                                        Re: Power suply doesn't work (DPS-214CP)

                                        Ok, that way, with the pin soldered I measure near 5 volts, same as I currently have at FB pin of DDA010.
                                        Attached Files

                                        Comment

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