Announcement

Collapse
No announcement yet.

VIZIO VO42L FHDTV10A No Video

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
    #1

    VIZIO VO42L FHDTV10A No Video

    Hi,
    I have been trolling this forum for the weekend trying to gleen all the info I can to fix a freebie I picked up from a friend. I have read multiple threads and figure it's time for some more direct assistance.. A Vizio VO42L FHDTV10A that the picture went out but still sound. I am a crack electronics fixer, I have fixed my bad caps on my Samsung 50inch LCD, also fixed the bad caps on my Frigidaire fridge control board and also regularly buy and fix Apple Iphones/ Ipods that have water damage and battery/screen issues for friends. I have no training with a multimeter but have been able to piece together info from this forum and youtube on how to check my new project and I do have a bottom of the line multimeter to use. I will take pictures asap to assist. Here is the issue so far. Amber light comes on when I plug in, turns white when I turn on with power button, and I get a flash from the right side of the panel(backlight i assume) when looking at the set from the back. I can see briefly during this flash the on screen menu/channel on the one side that lighted, but the left side does not flash but I can faintly see the CHANNEL 2 box in the upper side of screen that back light did not flash on. I took checked both master (left side) and slave (right side) inverter boards. Both seem to be in great shape, no pins popped or bulged on the chips, and I checked the small chips and all had a consistent reading of resistance per the research i have been able to do... I de-soldered the fuse on the power board and figured out how to check it with the multimeter, its good, re-soldered and still same issues. I have been trying to check the 2X24 volts and 12V and cant seem to get a reading on them at all. Not sure if i am checking correctly, just using the multimeter common and volt probes and touching the outer pins indicated in posts I have seen previously. I also switched the positions on the inverter plugins to the power board and still the slave (right) side inverter only flashed(backlight) both times. Not sure what this means so trying to figure still if it is power board or the inverter boards or the LCD board? Any help on how to troubleshoot from here? THanks for any assist!!!
    Pictures to follow.

    Thanks
    Brett
    Tags: None
    #2
    Re: VIZIO VO42L FHDTV10A No Video/ sound works

    Pics included now. Please help me troubleshoot the 12V pins and 24. step by step where to touch? what should read on the multimeter?
    Attached Files

    Comment

      #3
      Re: VIZIO VO42L FHDTV10A No Video

      place the black cable of the multimeter on the chassis or one of the screws holding down the board your checking and the red probe to the 12v pin or 24v pin. You should be getting something there. Make sure the meter is set to VDC (Volts DC)

      Comment

        #4
        Re: VIZIO VO42L FHDTV10A No Video

        To check the 12 volt output first plug in the TV and hit the power button so the amber light turns white. There are two spots you can use of ground. One is a mounting screw such as the one on the right side of the last picture. The other is you can use any of the pins labeled SGND on the output connectors.

        To measure voltages set your DMM to the 20 VDC range and either hold the black probe on the ground screw or jam it into the connector next to a wire to a pin labeled SGND. To measure voltages the best way is to stick the probe into the connector next to the wire.

        Given that you get a flash out of the backlights, odds are the problem is one of the inverters or a CCFL, not the power supply.

        PlainBill
        For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

        Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

        Comment

          #5
          Re: VIZIO VO42L FHDTV10A No Video

          Thanks for the guidance gentlemen. I appreciate your sharing of knowledge!! I did the DMM test as described and with vizio white and power on i get 24.3 V for the 2 24s and 11.7 for the 12. Does this eliminate my power as suspect?
          Sorry for the unfamiliarity with the acronym CCFL? LCD controller board? aka TCON?
          What would you recommend next?
          Brett

          Comment

            #6
            Re: VIZIO VO42L FHDTV10A No Video

            Originally posted by windfreik View Post
            Thanks for the guidance gentlemen. I appreciate your sharing of knowledge!! I did the DMM test as described and with vizio white and power on i get 24.3 V for the 2 24s and 11.7 for the 12. Does this eliminate my power as suspect?
            Sorry for the unfamiliarity with the acronym CCFL? LCD controller board? aka TCON?
            What would you recommend next?
            Brett
            First a little background. Any electronic device can be broken down into subsystems. Successful troubleshooting depends on identifying the defective subsystem and either replacing it or further identifying the cause of the failure and repairing the bad component.

            To use the current example, the TV breaks down into the power supply, main board, and display subsystems. The display further breaks down into the LCD panel and the backlight subsystems. The LCD panel subsystem breaks down into the actual LCD panel and the TCON - an acronym for Timing and CONtrol board. Because you can see information on the entire panel, a large part of the TV is shown to be working.

            The problem is with the backlight subsystem, which breaks down into the inverters, the CCFLs (Cold Cathode Fluorescent Light), and 'GOTCHA' - the section of the power supply that powers the inverters.

            The problem you describe is 'two seconds to black'. Essentially, if the inverter controller senses a problem, it shuts down. Possible problems include a CCFL that is not drawing enough current (or is open), a CCFL that is drawing too much current, a bad transformer or bad driver on the inverter, a power supply with bad filter caps, a CCFL that is arcing, etc, etc.

            In this case, I'm out of my depth. I've never worked on a TV with the dual inverters you have. A visual inspection using the pictures you supplied does not show a common failure - a blown controller, but the transistors could be shorted. Or it could be something as mundane as an open fuse. Or a cracked CCFL.

            PlainBill
            For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

            Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

            Comment

              #7
              Re: VIZIO VO42L FHDTV10A No Video

              I have been reading through all of these forums trying to make sense of a Vizio VX42L for days now and have found a few key differences in my model v. everyone else. First off I keep hearing about a master and slave inverter to contol the backlighting. On my model there is only one board (ballast board) to control the ccfls in the tv. I am having the issue of turning power on, the logo goes from orange to white, but get no sound or picture (also cannot control tv after initial power on and set must be unplugged to return to orange logo). I have checked for blown SM fuses and all show the appropriate voltages and continuity with power off. The u33 transistor on the main PCB gives 3.3v output so I have ruled that out of the equation. PSON output from the main PCB shows around 3 volts and I can hear the relay "click" on the power supply. All leads into the inverter show 24volts and I would expect to see at least a flicker from the ccfls? Is there a way to test the output to the lamps, or the lamps themselves? My DMM wil carry inputs of up to 750VAC but I understand that the output to these lamps is upwards of 1000v? I got the tv for free so I don't really want to dump a whole lot of money into it. Any ideas, or am i not getting something? I tried the flashlight trick to check the lcd panels but could see no discernible difference power on v. off. Any help would be greatly appreciated

              Comment

                #8
                Re: VIZIO VO42L FHDTV10A No Video

                I have to wonder why you have chosen to post this in a VO42 Thread - perhaps that is why your boards are different? use the search and post in a VX42 thread if appropriate or start your own.

                We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

                Please do not post inline and offsite as they slow down the loading of pages.

                Examples of what is needed
                https://www.badcaps.net/forum/attach...1&d=1290283049

                https://www.badcaps.net/forum/attach...7&d=1280167246

                It will be useful if you can say what the supposed fault was and a bit about yourself - skills tools etc.
                Please upload pictures using attachment function when ask for help on the repair
                http://www.badcaps.net/forum/showthread.php?t=39740

                Comment

                  #9
                  Re: VIZIO VO42L FHDTV10A No Video

                  I just repaired 2 of these.. Both had bad caps on master and slave board (inverters) In both cases, the tv repair person told the owner it was a bad panel... One of them the screen was flashing like a strobe light and the other was no picture.. 470uf 35v caps 2 per board..

                  Comment

                    #10
                    Re: VIZIO VO42L FHDTV10A No Video

                    I have the same issue with a VO42L. I have even replaced the capacitors, ICs and all FET transistors on both inverters and I still don't get any life from the panel. I can turn the TV on and off though.

                    Comment

                      #11
                      Re: VIZIO VO42L FHDTV10A No Video

                      VIZIO 42L: Could use some help:
                      HI, I'm tony, I have the same Vizio 42L , brief picture issue, Master back light inverter works briefly then goes out,has full picture briefly, I have audio, 5,12,24 volts are good, caps look good, chip look good, no swollen or anything that looks burnt, i have the Inverters out of the chassis, those large caps look good, solder good, no smell either. supply voltages to both inverters are there, I read there is 1000 vdc on those transistor packs in the inverters? Where's that voltage supposed to come from, those large coil xformers on the PS board? I did see that voltage marked anywhere or is AC? What's neck, I a ectronics tech 40 years on guitars and audio amps.

                      Comment

                      Previous template Next
                      Working...
                      X