Visio VW32L HDTV40A - no picture

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • ahickman
    Badcaps Veteran
    • Jan 2012
    • 233
    • USA

    #1

    Visio VW32L HDTV40A - no picture

    I have a Visio 32" LCD (VW32L HDTV40A) that was pulled from the trash. I have spent several hours looking at the obvious (bad caps, burned pcb boards, etc.) and found nothing obvious. Did my searches for helpful hints, but info on this model or similar is limited. Only specific thread was as follows:

    https://www.badcaps.net/forum/showth...hlight=hdtv40a

    So far I have done the following in terms of troubleshooting:

    Using an isolated transformer, I removed the power supply board and tested the various points (filtering cap, +5/12/24 volt diodes). I do have +5 volts on power up. When I connect +5V through a 3.3K ohm resistor to PWR_ON pin, I get a brief +12/24 volts but it quickly decays.

    Can anyone suggest a next step in troubleshooting? It seems as though my power supply is OK, but it is shutting all but standby off shortly after power up.

    Aaron
    Attached Files
  • ahickman
    Badcaps Veteran
    • Jan 2012
    • 233
    • USA

    #2
    Re: Visio VW32L HDTV40A - no picture

    One last bit of information I forgot to mention regarding the symptoms....with all boards plugged in and the set powered up by AC, the VISIO symbol on front lights (standby voltage), but when the power button is pressed, the VISIO symbol goes orange, but looks unstable (it kinda wavers) like there is a short or intermittent connection. No picture. No sound and no +12/24 volts.

    Comment

    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK

      #3
      Re: Visio VW32L HDTV40A - no picture

      Someone else on these forums (Tetranitrate) has a very similar problem. In his case it seems to be a shorted T-con, so try disconnecting the connector with the thick black lead. You should get no picture or a white screen but it might then power up and give sound.
      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: Visio VW32L HDTV40A - no picture

        You should bench test the power supply again, using two 12v bulbs in series and attach them to the 24vdc output, then turn it on as before sunig the 3.3K resistor, the lamps should stay on, if not, you still have problem in the 24/12vdc power supply circuits.
        See how I test the power supply here:
        http://s807.photobucket.com/albums/y...%20SV470XVT1A/
        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

        • ahickman
          Badcaps Veteran
          • Jan 2012
          • 233
          • USA

          #5
          Re: Visio VW32L HDTV40A - no picture

          OK, tried the dual 12v lights in series and get 1 second of lamp life.

          Comment

          • tom66
            EVs Rule
            • Apr 2011
            • 32560
            • UK

            #6
            Re: Visio VW32L HDTV40A - no picture

            Originally posted by ahickman
            OK, tried the dual 12v lights in series and get 1 second of lamp life.
            With the 3.3k resistor? Any connections going to main board? If so, disconnect them all.
            Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
            For service manual, schematic, boardview (board view), datasheet, cad - use our search.

            Comment

            • ahickman
              Badcaps Veteran
              • Jan 2012
              • 233
              • USA

              #7
              Re: Visio VW32L HDTV40A - no picture

              With only the controller board connected the power supply, I noticed the processor heat sink was a bit warm. Inverting a can of compressed air, I sprayed the board down and then blew moisture from a breath of air across the board to look for hot spots. Found that U7 (marking on chip is K401, G117 which Digikey shows as a 5V LDO regulator) was extremely hot. So hot that I burned the pad of my finger! This looks like the power to the processor. I flipped the board over to test the caps ESR and noticed that somewhere along the line I had dislodged three VERY tiny SMD capacitors (CB82, CB83 and CB109). So small and little chance of finding them. Ugggh!
              Attached Files

              Comment

              • ahickman
                Badcaps Veteran
                • Jan 2012
                • 233
                • USA

                #8
                Re: Visio VW32L HDTV40A - no picture

                Tom66, when testing the PS, I had no connections to any boards. Just the lonesome power supply.

                Comment

                • tom66
                  EVs Rule
                  • Apr 2011
                  • 32560
                  • UK

                  #9
                  Re: Visio VW32L HDTV40A - no picture

                  Originally posted by ahickman
                  Tom66, when testing the PS, I had no connections to any boards. Just the lonesome power supply.
                  So this seems to indicate a fault with the power supply.

                  What experience do you have with debugging power supplies?
                  Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                  For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                  Comment

                  • ahickman
                    Badcaps Veteran
                    • Jan 2012
                    • 233
                    • USA

                    #10
                    Re: Visio VW32L HDTV40A - no picture

                    Don't mind admitting that I am some what of a newbie to SMPS troubleshooting. I understand the major components/functions of the SMPS, but don't have the necesary experience.

                    Comment

                    • tom66
                      EVs Rule
                      • Apr 2011
                      • 32560
                      • UK

                      #11
                      Re: Visio VW32L HDTV40A - no picture

                      Originally posted by ahickman
                      Don't mind admitting that I am some what of a newbie to SMPS troubleshooting. I understand the major components/functions of the SMPS, but don't have the necesary experience.
                      It definitely helps to have a background. I am still a newbie.

                      I just saw you post about the LDO. The LDO is probably hot because it is unstable without the caps. If you find the datasheet for the LDO, you can find the manufacturer's recommended capacitors and replace them. I wouldn't recommend running it with the hot LDO. It could damage the processor.
                      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                      Comment

                      Related Topics

                      Collapse

                      • Tr0ll
                        T-con suspect issue. Both ribbon cables no picture. One ribbon cable ok. (58pus8545)
                        by Tr0ll
                        Hi guys! I realized you have a lot of knowledge here so i am hoping you could point me in right direction with my odd issue.

                        The Tv is a Philips 58PUS8545/12, it had no picture but working backlights.

                        Original T-con:
                        Opened the Tv and tested to unplug one ribbon cable at a time. With this test i could see that i got fine picture on both halves as long as there was only one ribbon cable connected, with two connected picture were gone.

                        First replacement T-con:

                        I thought it might be t-con and ordered new t-con from china(supposedly tested)...
                        10-07-2023, 07:48 PM
                      • JJAAMM
                        SAMSUNG UN55KS9000F picture fades then distorts into vertical lines after 20 seconds
                        by JJAAMM
                        This was my main TV for the last 6 years. I'm not inclined to throw out a $2600 TV so quickly so I'm trying to investigate the issue.

                        Problem
                        TV was disconnected from power for 6 months during construction. When I plugged it yesterday picture was fine, after 30 seconds it dimmed then started developing horizontal lines, picture then starts to ghost vertically until it degrades into vertical streaks. TV always displays a perfect picture when cold. I can unplug TV for 5 minutes and plug it back in and picture is restored for 20 seconds. I can also keep it in standby mode...
                        07-06-2023, 06:01 AM
                      • TR103
                        Samsung TV model UE50TU: rebooting, backlight, sound, but no picture
                        by TR103
                        Hi, I have a Samsung UE50TU with:
                        - sound and backlight, but no picture
                        - when it arrived, it had a picture for a few seconds
                        - it keeps rebooting
                        - without ribbon cable between the two panel boards, it does not reboot but I have no picture
                        - without cable between mainboard and lcd panel, it does not reboot (but obviously i have no picture)
                        - when i try a tape fix, its keeps rebooting, unless I tape off pin 1 (the innermost pin). In that case it does not reboot but I have no picture.

                        - without cable between mainboard and lcd panel and with a jumpered...
                        01-22-2025, 04:12 PM
                      • Mgiffune
                        Samsung UN60EH6000F Black Screen, Backlight and Sound Good. Power Cycle Returns Picture
                        by Mgiffune
                        I have a 60 inch Samsung UN60EH6000F flatscreen TV. The screen went black a few months ago Sound is good, backlight is good, no menu. I replaced the TCon board with a used board purchased from Ebay. It worked fine for a 3-4 months, then the screen started ‘fading' back. Once again, sound is good, backlight is good, no menu. However, this time the picture looks fine for about 10-15 minutes, then fades back. If I power cycle the TV, the display reappears, for another 10-15 minutes, then fades black again. Repeatable ever time.

                        I ordered a supposedly ‘new' Tcon board this time, and
                        ...
                        06-09-2024, 10:28 AM
                      • Rauni
                        Philips 58PUS7805/12 showed no picture; after T-Con replacement, shows halo
                        by Rauni
                        Hello, this is my first post on this forum, and my first attempted to repair a TV.

                        My Philips 58PUS7805/12 stopped working recently. It is not that old, about 5 years. We were on a trip for a few days and when we came back, it had stopped working out of a blue (Perhaps our house was hit by a lightning strike? Don't know.)

                        Read from a guide that I should test if the screen shows picture with one of the T-Con cables disconnected. Did that, it showed perfect picture (first on left, later on right side).

                        Read also that we should test what happens if we...
                        10-01-2023, 12:06 AM
                      • Loading...
                      • No more items.
                      Working...