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Vizio L32 HDTV10A - Wont turn on

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    #1

    Vizio L32 HDTV10A - Wont turn on

    Got another free LCD TV to play around with

    I plugged it in and the amber standbye light came on and that's as far as it'll go. TV does not respond to any button pushes.

    Power supply is in good shape. Only the 5v line is available during standbye, but I tested the 19v and 12v lines by tricking the power supply into turning on fully and everything tested fine... atleast without any load.

    Started probing around elsewhere and determined that there was no sense voltage going out to the power button (or any other button). So of course the TV isn't going to be able to turn on.

    Suspected there was a problem with the main board. Made sure it was properly receiving 5v from the power supply. Noticed there was a 3.3v regulator there and that checked out as well.

    I was going to start downloading datasheets and probing around more but decided I might as well take some pictures and upload them here incase anyone had any insight. As I was taking the pictures I noticed an abnormality on one of the tiny smd components. It has a small bump in the middle...

    Having trouble getting my digital camera to take good enough pictures but hopefully somebody can see well enough from them... I tried using the flash onetime on the closeup shot and it actually made the bump much easier to see (component circled in red)

    The suspected bad component is U26... and it happens to be near the connector that goes out to the board with the power button on it. It's hard to read the part number partly because its so small but also because the bump is right where one of the letters should be. It's really hard to say but I think the part number is NTP4 or N1P4 or something similar.

    I'll see if I can get better pictures but in the mean time I've attached the ones Ive taken so far.
    Attached Files
    Tags: None
    #2
    Re: Vizio L32 HDTV10A - Wont turn on

    Hi, I am sorry I do not have an answer for you but I am having the same problem as you on my display. If you don't mind me asking. How were you able to trick the power supply to come up?

    Comment

      #3
      Re: Vizio L32 HDTV10A - Wont turn on

      Did you carefully clean it? Could be flux glop sitting atop the transistor. Did you ohm it?

      Usually NPN or PNP and it is general purpose because this is not high speed stuff because this is on this circuit for the function input (buttons).

      Cheers, Wizard

      Comment

        #4
        Re: Vizio L32 HDTV10A - Wont turn on

        Originally posted by den3720
        Hi, I am sorry I do not have an answer for you but I am having the same problem as you on my display. If you don't mind me asking. How were you able to trick the power supply to come up?
        One of the connectors has a line labelled "remote" which is connected to the main pcb. When the main pcb wants to come out of standbye, it puts 3.3v on this line which turns on the 12v and 19v lines on in the power supply.

        I simply isolated the power supply from the rest of the tv and then used an external 3.3v supply connected + to the remote line and - to ground.

        Comment

          #5
          Re: Vizio L32 HDTV10A - Wont turn on

          Originally posted by Wizard
          Did you carefully clean it? Could be flux glop sitting atop the transistor. Did you ohm it?

          Usually NPN or PNP and it is general purpose because this is not high speed stuff because this is on this circuit for the function input (buttons).

          Cheers, Wizard
          It appears the component is damaged... It does not appear to be flux.

          Did some searching around and apparently its a common problem for this component to be defective in these sets. I found a post on fixya where a guy suggests removing u26 and replacing it with a diode. Doesn't seem like the best solution, but I tried it to see if it would fix the problem.

          And sure enough it did. I installed a diode across (what I believe to be) collector and emitter. He says to install it across pins 2 and 3.

          So yea. TV is working great now.

          Comment

            #6
            Re: Vizio L32 HDTV10A - Wont turn on

            I thought that was for buttons as "function" is what it means.

            And this hack is bad idea. Must install a suitable substitute transistor. I think this one uses PNP if it pulls 3.3V up when microcontroller pulls base gate up.

            Comment

              #7
              Re: Vizio L32 HDTV10A - Wont turn on

              Originally posted by Wizard
              I thought that was for buttons as "function" is what it means.

              And this hack is bad idea. Must install a suitable substitute transistor. I think this one uses PNP if it pulls 3.3V up when microcontroller pulls base gate up.
              Definetly. I'm not going to leave the diode in there, I just installed it temporarily to see if it would get the TV working again.

              I believe its PNP also but I'm not positive atm. I'll see what I can find.

              Comment

                #8
                Re: Vizio L32 HDTV10A - Wont turn on

                Got the parts and service manual for this TV off the net.

                U26 is listed as a ASM809 which is a 3 pin Microcontroller Power Supply Supervisor. Its function is to keep the microcontroller in a reset state for a brief time during powerup, down and brownouts in order to avoid any errors during those time.

                My U26 is faulty and is holding the microprocessor in reset. By installing the diode across pins 2 and 3, I am forcing the reset pin high and allowing the microprocessor to start (albiet without the safety of the brief time delay during powerup).

                I'll order a new one, install it and post back.

                Comment

                  #9
                  Re: Vizio L32 HDTV10A - Wont turn on

                  Originally posted by aliasdck View Post
                  Got the parts and service manual for this TV off the net.

                  U26 is listed as a ASM809 which is a 3 pin Microcontroller Power Supply Supervisor. Its function is to keep the microcontroller in a reset state for a brief time during powerup, down and brownouts in order to avoid any errors during those time.

                  My U26 is faulty and is holding the microprocessor in reset. By installing the diode across pins 2 and 3, I am forcing the reset pin high and allowing the microprocessor to start (albiet without the safety of the brief time delay during powerup).

                  I'll order a new one, install it and post back.
                  I have the EXACT Same problem and Tv and found a replacement microprocessor. I am having trouble with the "Over voltage" and "Under voltage" thresholds, could you tell me which one you used?
                  Im looking at Mouser and they have 5 different which range from 2.93 to 4.63 v.
                  you input on this would be very helpful.
                  thanks, kyle

                  Comment

                    #10
                    Re: Vizio L32 HDTV10A - Wont turn on

                    Since aliasdck mentioned the supply logic is on 3.3v, either the 2.93 or 3.08 volt will do.
                    Originally posted by PeteS in CA
                    Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                    A working TV? How boring!

                    Comment

                      #11
                      Re: Vizio L32 HDTV10A - Wont turn on

                      Friend gave me his after buying at one of each replacement board. I'm thinking both main boards (the original and the replacement boards) have a bad U26 ASM809 part. I'd love to know about progress here, too.

                      Comment

                        #12
                        Re: Vizio L32 HDTV10A - Wont turn on

                        Has anything come of this thread. So far I have tried the resistor, the diode, and every other trick I found on the net. Still no tv on for me.

                        Comment

                          #13
                          Re: Vizio L32 HDTV10A - Wont turn on

                          Do you get the standby 5V OK? Check the voltage of the LDO REGULATORS? More info about what you have done so far will help.
                          https://www.badcaps.net/forum/showth...391#post274391

                          http://s807.photobucket.com/albums/y...%20L32HDTV10A/
                          Last edited by budm; 11-09-2012, 10:06 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

                            #14
                            Re: Vizio L32 HDTV10A - Wont turn on

                            Originally posted by aliasdck View Post
                            Got the parts and service manual for this TV off the net.

                            U26 is listed as a ASM809 which is a 3 pin Microcontroller Power Supply Supervisor. Its function is to keep the microcontroller in a reset state for a brief time during powerup, down and brownouts in order to avoid any errors during those time.

                            My U26 is faulty and is holding the microprocessor in reset. By installing the diode across pins 2 and 3, I am forcing the reset pin high and allowing the microprocessor to start (albiet without the safety of the brief time delay during powerup).

                            I'll order a new one, install it and post back.
                            So What happened? Did you get the part? Did you install it? Did it work?

                            Comment

                              #15
                              Re: Vizio L32 HDTV10A - Wont turn on

                              Originally posted by Keshetisrael View Post
                              So What happened? Did you get the part? Did you install it? Did it work?
                              You do realize that this thread is a few years old and the OP hasn't logged on for two years?

                              Comment

                                #16
                                Re: Vizio L32 HDTV10A - Wont turn on

                                I am A tech and Vizio call's these TV's unrepairable and they would like you to by A new set but try this little trick that we do at my shop unplug the TV from the wall and hold the power button in for 45 sec. then plug the set back in the wall then press power this should work with most Vizio TV sets most techs will charge you $50 to A $150 to do this for but why when toy can do it your self for free at my shop if we can fix it for free you get it back for free

                                Comment

                                  #17
                                  Re: Vizio L32 HDTV10A - Wont turn on

                                  Holy archives batman!! Lol. Thanks for the tip thou.
                                  Did I leave the soldering iron on?

                                  Comment

                                    #18
                                    Re: Vizio L32 HDTV10A - Wont turn on

                                    The number that is stamped on this device is NAG8. I'll research it further and leave a message here so everyone can use it.

                                    Comment

                                      #19
                                      Re: Vizio L32 HDTV10A - Wont turn on

                                      Here is the part number and the description for U26 which was taken by the service manual. U26 0430-7033-3016 IC ASM809MEURF-T 4.38V SOT23 LF

                                      Ignore my previous reply that just said the stamped part number was NAG8.

                                      Comment

                                        #20
                                        Re: Vizio L32 HDTV10A - Wont turn on

                                        Data sheet:-
                                        http://www.datasheetlib.com/datashee...html#datasheet
                                        Willing to help but I'm no expert.

                                        Comment

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