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    #1

    Vizio VX32L no 12v

    I've been searching threads all morning but haven't found anything that helps me with my issue. The Tv turns on from amber standby to white but after 2 seconds it goes back to standby. I'm getting 5v standby but nothing for 12v. In the 2 seconds the tv is on i can check all the regulators on the main board and they are all correct.

    The service manaul lists in dc-dc converter flowchart 12v present with the power turned on to check J7 pin 1 (Ps-On) is getting 3v. I'm getting zip (0v) at the ps-on pin. I disconnected the tcon to see if the ps-on would go higher but that did nothing. I then disconnected the inverter and again nothing on the ps-on pin. I pulled the caps on the power supply and checked the esr and capacitance and they are all good. Checked diodes and they are good. Resistors are good too. I don't know where to go from here. The large cap reads 159.6v in standby and 384v with the tv on for the 2 seconds.

    There are 2 fuses on the mainboard. Both read 0.00 ohm. With the tv on for 2 seconds i get 5v at the one fuse but nothing at the other. I'm assuming the second fuse that i'm getting non reading on should be 12v. SO i'm thinking that this is a power supply issue. I uploaded the service manual for anyone that needs it. Its 4.74 MB though.

    Any suggestions would be appreciated
    Thanks
    Attached Files
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    #2
    Re: Vizio VX32L no 12v

    Originally posted by Mr Bill View Post
    In the 2 seconds the tv is on i can check all the regulators on the main board and they are all correct.
    I'm not suggesting you are making this mistake, but the last time someone wrote the above regarding the voltage regulators, he was dead wrong. Luckily for him, I asked to post the actual readings, and he fixed his TV for 52 cents. Now if I can only find that thread (sigh only 2,610 google hits).

    Edit: found it (from post #1 - "All my voltage regulators are testing perfectly.")

    https://www.badcaps.net/forum/showthread.php?t=21269

    So I prefer people list the part number and the voltages of all pins so we can verify. For example,

    U10
    AS1117-33
    pin 1 = 0.0
    pin 2 = 3.3
    pin 3 = 5.0

    The service manaul lists in dc-dc converter flowchart 12v present with the power turned on to check J7 pin 1 (Ps-On) is getting 3v. I'm getting zip (0v) at the ps-on pin.
    You can try disconnecting all your boards and jumpering PS-ON with a resistor. Like so

    https://www.badcaps.net/forum/showpo...1&postcount=45

    If 12V comes up, then some other board is dragging down the 12V rail or the main board isn't sending PS-ON. If it does not come up, then something on the power board is dragging it down.
    Last edited by retiredcaps; 07-21-2012, 04:04 PM. Reason: edit: PS-ON
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      #3
      Re: Vizio VX32L no 12v

      Here is the regulator values

      U2
      AS1117
      pin 1 = 2.050
      pin 2 = 3.296
      pin 3 = 5.0

      U4
      AS1117
      pin 1 = 2.068
      pin 2 = 3.312
      pin 3 = 5.0

      U7
      AS1117
      pin 1 = 0.0
      pin 2 = 1.249
      pin 3 = 3.326

      U8
      AS1117
      pin 1 = 2.067
      pin 2 = 3.312
      pin 3 = 5.0

      U9
      AS1117
      pin 1 = 0.253
      pin 2 = 1.549
      pin 3 = 3.326

      U33
      AS1117
      pin 1 = 2.067
      pin 2 = 3.327
      pin 3 = 5.0

      U10
      1084
      pin 1 = 1.324
      pin 2 = 2.574
      pin 3 = 4.98

      All the regulators are adjustable. I replaced U7 with a brand new one from digikey. The old one was reading .768 on the adj/gnd pin but now the new one reads 0. I tested U7 from Vout to GND and i'm getting 96.1ohm which is what prompted me to change U7 but i'm still getting the same 96.1 ohm. The dc-dc converter flowchart claims U7, U8, & U10 should have 1.8v on pin 2.

      I would pull the power supply and run a resistor but i am unsure which pin i ps-on on the supply (pic 3). The legend on the board doesn't specifically state a ps-on pin.

      Comment

        #4
        Re: Vizio VX32L no 12v

        Originally posted by Mr Bill View Post
        I replaced U7 with a brand new one from digikey.
        What part number did you order from digikey?

        I would pull the power supply and run a resistor but i am unsure which pin i ps-on on the supply (pic 3). The legend on the board doesn't specifically state a ps-on pin.
        Are there any markings on the backside of the powerboard?
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          #5
          Re: Vizio VX32L no 12v

          497-1244-1-ND is the part i ordered. THere is nothing on the bottom of the power supply.

          Comment

            #6
            Re: Vizio VX32L no 12v

            Is CN3 the connector to the main board?
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              #7
              Re: Vizio VX32L no 12v

              Originally posted by Mr Bill View Post
              The service manaul lists in dc-dc converter flowchart 12v present with the power turned on to check J7 pin 1 (Ps-On) is getting 3v.
              Where is J7 pin 1? If you can find it, put your multimeter on continuity and "ohm out" the board connector. Once you find it that should be your ps-on.
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                #8
                Re: Vizio VX32L no 12v

                Originally posted by retiredcaps View Post
                Where is J7 pin 1? If you can find it, put your multimeter on continuity and "ohm out" the board connector. Once you find it that should be your ps-on.
                I ohmed out J7 pin 1 back to the power supply and it is a ground pin. I thought this is odd so i ohmed J7 pin 1 to the chassis and its 0.000, so is this right? I don't want to short anything out. J7 is on the main board, it's the connector that goes to the tcon board.

                Comment

                  #9
                  Re: Vizio VX32L no 12v

                  Originally posted by Mr Bill View Post
                  J7 is on the main board, it's the connector that goes to the tcon board.
                  Can you post a close up picture of this?
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                    #10
                    Re: Vizio VX32L no 12v

                    Btw, looking at some other VX32L threads, it seems to me there is more than one version of the power board which is not surprising. In another thread, the ps_on pin is clearly marked. See last picture in

                    https://www.badcaps.net/forum/showpo...7&postcount=13
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                      #11
                      Re: Vizio VX32L no 12v

                      Let me know if you need anymore.
                      Attached Files

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                        #12
                        Re: Vizio VX32L no 12v

                        Originally posted by Mr Bill View Post
                        Let me know if you need anymore.
                        I must be blind, I can't see the pcb designation J7? Maybe the angle of the picture is hiding it?
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                          #13
                          Re: Vizio VX32L no 12v

                          That's my fault. The marking is under the connector that was connected so it couldn't be seen. According to shop jimmy there are 2 power supplies for this tv.
                          Attached Files

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                            #14
                            Re: Vizio VX32L no 12v

                            1) On J7, see if pin 1 and 2 have continuity to ground.

                            2) Are J7 pins 1 and 2 have a black color wire?

                            It isn't universal, but if pins 1 and 2 are black colored wires, it might represent gournd?

                            3) If shopjimmy owners are saying there are 2 power supplies, I think the service manual you posted may be the wrong one for your power supply.

                            4) See if there is another V32XL service manual.

                            5) Does your TV have more than just VX32L in the part number?
                            Last edited by retiredcaps; 07-21-2012, 08:18 PM.
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                              #15
                              Re: Vizio VX32L no 12v

                              6) Also, pins 1-4 on J7 usually carry ground/power to the t-con and it would be strange to find ps_on on that connector.
                              Last edited by retiredcaps; 07-21-2012, 08:41 PM. Reason: clarify pins 1-4 on J7
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                                #16
                                Re: Vizio VX32L no 12v

                                7) From looking at the other boards (post #10), I think your black wire (pin 13 or pin1 depending on where you start) labeled REMOTE on CN3 is your ps_on. I came to this conclusion because your main boards are the same (0171-2272-2174). You can see if I'm right or not.

                                https://www.badcaps.net/forum/attach...5&d=1322285466
                                Last edited by retiredcaps; 07-21-2012, 08:21 PM.
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                                  #17
                                  Re: Vizio VX32L no 12v

                                  The model number is VX32L nothing else and the service manual i uploaded is vx32l. I have been wondering if the service manual was incorrect. There are some differences in the dc-dc converter flowchart, U5 & U6 aren't LDO regulators to start with not to mention the J7 pin 1 that you have pointed out. I believe i saw this morning someone stated using a VW32L servce manual but i'm trying to find that post.

                                  Comment

                                    #18
                                    Re: Vizio VX32L no 12v

                                    I put a 3.3k resistor from "remote" to 5v stb. The power supply did turn on but i'm still getting 0 for 12v. I checked the large cap and its at 386v so the pfc is activating. So i'm guessing that something in the power supply is bad.

                                    Comment

                                      #19
                                      Re: Vizio VX32L no 12v

                                      Originally posted by Mr Bill View Post
                                      So i'm guessing that something in the power supply is bad.
                                      1) See if D7, D8, and D9 are shorted.

                                      2) Can we also get a pic of the underside of the power supply?

                                      3) We are looking for a SMPS IC for the secondary voltages. It might be an 8 pin IC.
                                      Last edited by retiredcaps; 07-21-2012, 09:23 PM.
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                                        #20
                                        Re: Vizio VX32L no 12v

                                        Here is a picture of the bottom of the power supply. I removed D7, D8, & D9 and they are good. I think i may have found something but you be the judge. On the top of the power supply hidden under a heatsink is a DIP-8 ic (A6252M), the datasheet lists it as a flyback switching regulator. If i measure pin 1 (Mosfet source/overcurrent protection) to ground i get 0.006 ohm.

                                        Maybe this is what is causing the power supply to shutdown and 12v not be present.
                                        Attached Files

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