Fixed a ViewSonic N3260w

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  • 12rounds
    Member
    • Sep 2014
    • 41
    • United States

    #101
    Re: Fixed a ViewSonic N3260w

    i am not getting 12 or 24v. i am getting about 65v in both of these places. there is also something wrong with q1 and q2 - possible with ic1. i get 346v on q1 drain, a pulsing low on the gate and what looks like nothing on the source. i have pretty much nothing on q2 anywhere.

    i have 13.2v on p12 of ic1 so it is getting voltage. i have nothing on the EN1 line (ic1p8). i think that i have an issue with optocoupler 1c4 - i see that there is 5v on p1 and 4v on pin2, so the diode should be coming on. on the primary side of the coupler i have 14v on p4 (collector) and -8v on the emitter (p3).

    i don't really know where to go from here. is t2's only output 5v? and t1 12 and 24v?
    Last edited by 12rounds; 10-19-2014, 05:31 PM.

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #102
      Re: Fixed a ViewSonic N3260w

      "i am not getting 12 or 24v. i am getting about 65v in both of these places." I do not understand on 65V reading.
      "t1 12 and 24v?" That is correct, IC1 L6598 is the SMPS for the 12V/24V power supply.
      Page 15:
      PIN 8:
      Comparators
      Two CMOS comparators are available to perform protection schemes.
      Short pulses (≥ 200 ns) on comparators input are recognized. The EN1 input (active high),
      has a threshold of 0.6 V (typical value) forces the device in a latched shut down state (e.g.
      LVG low, HVG low, oscillator stopped), as in the under voltage conditions. Normal operating
      conditions are resumed after a power-off power-on sequence. The EN2 input (active high),
      with a threshold of 1.2 V (typical value) restarts a Soft Start sequence (see timing
      diagrams). In addition the EN2 comparator, when activated, removes a latched shutdown
      caused by EN1.
      So if pin 8 sees 0.6V 200 nano second pulse, it will then trip the shutdown.
      You should check C15 (0.022uF 1KV cap) which is connected to one end of T1 Primary winding to ground, if the capacitance goes down, it will produce enough pulse to trip the IC.
      Attached Files
      Last edited by budm; 10-19-2014, 05:56 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

      • 12rounds
        Member
        • Sep 2014
        • 41
        • United States

        #103
        Re: Fixed a ViewSonic N3260w

        i am reading 65v on cns1 where i should have 12 and 24v. i don't know why....

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #104
          Re: Fixed a ViewSonic N3260w

          That has to be error in measurement, the 12V/24V are in the secondary side so you will use the chassis as the ground ref.
          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

          • 12rounds
            Member
            • Sep 2014
            • 41
            • United States

            #105
            Re: Fixed a ViewSonic N3260w

            i switched my reference. still getting the weird 65v. it doesn't make any sense.

            i'm confused because in order to get anything on cns1/2 i need to see voltage on the source side of q1 or nothing is going to propagate to across to the secondary side of t1. i don't see anything on q1 source, but somehow there is still 65v.

            what i really don't get is where the different voltages are coming from. i thought that t2 was only 5v. the only thing that makes me wonder is the way that the schematic is drawn to show crs1 as a part of the t2 5v supply. then there is the cut-away showing crs1 and crs2 which doesn't make any sense - why aren't they labeled as being on the t1 secondary?
            Last edited by 12rounds; 10-19-2014, 06:22 PM.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA

              #106
              Re: Fixed a ViewSonic N3260w

              "i switched my reference. still getting the weird 65v. it doesn't make any sense" OK, in the primary side of the circuit, you have to use negative leg of the filter cap as the ground ref.
              The CNS1 and CNS2 are in the secondary side so the ground ref is the chassis, so CNS2 PIN 1~5 (24vdc OUTPUT) you are getting 65V? are you sure you have the meter set to VDC? How about CNS1 pin 9~11, are you getting 5VDC?
              Bottom line, what are you getting at 5V PINS, 12V PINS, 24V PINS?
              Do not try to measure the voltage at the Source of Q1,if it is running you can have very high voltage that can damage your meter, it will be high frequency AC that meter cannot measure.
              How about C15 capacitance?
              Last edited by budm; 10-19-2014, 06:59 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

              • 12rounds
                Member
                • Sep 2014
                • 41
                • United States

                #107
                Re: Fixed a ViewSonic N3260w

                Will check and double check tomorrow and post results.

                Comment

                • 12rounds
                  Member
                  • Sep 2014
                  • 41
                  • United States

                  #108
                  Re: Fixed a ViewSonic N3260w

                  OK. so, i don't know where my head was at before, but even knowing that i had 2 different ground references, i must have been on the wrong one measuring CNS1 and 2.

                  here are the results, with respect to chassis GND:
                  CNS2
                  pin 1-4 = 0
                  pin 5-8 = 0
                  p9 = 4.8
                  p10 = 4.8

                  CNS1
                  pin 1-4 = 0
                  p 5-6 = 2.5
                  p 7-9 = 5
                  p 10 = 3.4
                  p 11-12 = 4.8

                  i have a diagram that says p12 on cns1 is over current protect and should be 0v. i did not check capacitance of c15 - mains side is 346v, d12 side is 465v.
                  Last edited by 12rounds; 10-20-2014, 06:29 PM.

                  Comment

                  • 12rounds
                    Member
                    • Sep 2014
                    • 41
                    • United States

                    #109
                    Re: Fixed a ViewSonic N3260w

                    Went back and re-read to re-think...

                    Question (may be stupid and obvious) - active high means that the voltage on a pin will always be above the threshold in normal operation, correct?

                    If so, my pin8 is at pretty much 0. reading the description you posted of how the comparator and EN1/2 work, i expect that something is wrong in this portion of the circuit. I went through to verify the schematic diagram and there are some differences here. I think that i have an issue with optocoupler ic4 - i see that there is 5v on p1 and 4v on pin2, so the diode should be coming on. on the primary side of the coupler i have 14v on p4 (collector) and -8v on the emitter (p3).

                    2 questions - 1. if t1 is not on, where am i getting 14v from (measured on the secondary side of the optocoupler)? 2. what could cause the primary side of the optocoupler on the emitter to drop below reference and read as -8v?

                    i will lift a leg on c15 and try and measure its capacitance with my pos cap meter....
                    Last edited by 12rounds; 10-22-2014, 11:52 AM.

                    Comment

                    • 12rounds
                      Member
                      • Sep 2014
                      • 41
                      • United States

                      #110
                      Re: Fixed a ViewSonic N3260w

                      tried to measure cap c15... i think i have an issue, but i don't know if it is equipment or the part. i have a fluke12 to measure capacitance. 0.022u is out of range so i figured i could connect in series with a cap of known value and read the sum and calculate. i think that the meter has the resolution to do this in the 1u range. i get a reading of 0.001u when i do this. is this a equipment problem or a bad part?

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #111
                        Re: Fixed a ViewSonic N3260w

                        You hook up a know value cap (something close to the same range) in parallel with C15, if the C15 is good then the reading should not be the same as the known good value, it should be = known value + 0.022uF. You will do the test with cap off the board.
                        Last edited by budm; 10-22-2014, 05:08 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

                        • 12rounds
                          Member
                          • Sep 2014
                          • 41
                          • United States

                          #112
                          Re: Fixed a ViewSonic N3260w

                          so, i have a cap measuring 1.94u. In parallel with c15 my reading is still 1.94. i will try and find a cap tomorrow at work with a value closer to 0.022u, but is this looking like like i should replace the ceramic discs on the board? i am ready to spend the dollar!

                          question- the marking on the side of c15 is:
                          rr
                          102k
                          1kv64

                          doesn't that make this a 0.001uF cap?
                          Last edited by 12rounds; 10-22-2014, 07:21 PM.

                          Comment

                          • 12rounds
                            Member
                            • Sep 2014
                            • 41
                            • United States

                            #113
                            Re: Fixed a ViewSonic N3260w

                            measured c15 in parallel with another ceramic disc which measured 0.117u. I get 0.118u, which is right on, I believe. I don't have a way to measure esr.

                            Comment

                            • budm
                              Badcaps Legend
                              • Feb 2010
                              • 40746
                              • USA

                              #114
                              Re: Fixed a ViewSonic N3260w

                              So the know ceramic cap is measured at 0.117uF, then you connect the C15 0.022uf in parallel, then the total capacitance should be = 0.117 +0.022 = 0.139uF.
                              Am I reading your post correctly?
                              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

                              • 12rounds
                                Member
                                • Sep 2014
                                • 41
                                • United States

                                #115
                                Re: Fixed a ViewSonic N3260w

                                C15 is marked as 102k making it a 0.001uf cap. Unless i am misunderstanding the code.

                                Comment

                                • budm
                                  Badcaps Legend
                                  • Feb 2010
                                  • 40746
                                  • USA

                                  #116
                                  Re: Fixed a ViewSonic N3260w

                                  .001 will be way too small, I think the SCH we are using does not have the matching designators to the board we are working on.
                                  Attached Files
                                  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

                                  • 12rounds
                                    Member
                                    • Sep 2014
                                    • 41
                                    • United States

                                    #117
                                    Re: Fixed a ViewSonic N3260w

                                    hang on... on a different page again. talking about c15 i referred to the schematic. after looking at your picture i realized that you are talking about something different! Let me pull that cap and check it
                                    Last edited by 12rounds; 10-23-2014, 11:41 AM.

                                    Comment

                                    • 12rounds
                                      Member
                                      • Sep 2014
                                      • 41
                                      • United States

                                      #118
                                      Re: Fixed a ViewSonic N3260w

                                      meter reads this one (c16) as 0.021uf

                                      any thoughts on the ic4 question from post #109? there are some circuit changes compared to the schematic.
                                      Attached Files
                                      Last edited by 12rounds; 10-23-2014, 12:55 PM.

                                      Comment

                                      • 12rounds
                                        Member
                                        • Sep 2014
                                        • 41
                                        • United States

                                        #119
                                        Re: Fixed a ViewSonic N3260w

                                        i replaced the optocoupler ic4. i still have weird measurements between NTC3 and EN1 of IC1. i don't understand how a i can have so many unpredicted changes in polarity across ic4 and along the feedback net???

                                        NTC1 has to be bad. it is dropping nearly 14v. i think zd3 may be bad also. i don't have much of a clue what the values of these should be - any ideas?
                                        Last edited by 12rounds; 10-28-2014, 06:02 PM.

                                        Comment

                                        • Pableros
                                          New Member
                                          • Mar 2015
                                          • 2
                                          • España

                                          #120
                                          Re: Fixed a ViewSonic N3260w

                                          Necesito ayuda urgente
                                          VALORES DE ZD-1 Y ZD-3 DE VIEWSONIC FSP228-3F01
                                          ESTAN EN CORTO Y EN EL DIAGRAMA NO VIENE
                                          Por favor si alguien lo sabe los valores
                                          Gracias amigos

                                          Comment

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