Plasma 42V7 problem - please help!!!

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Th3_uN1Qu3
    Believe in
    • Jul 2010
    • 6031
    • Romania

    #61
    Re: Plasma 42V7 problem - please help!!!

    Okay, this here says:

    DC 5.2v
    Va: 65v Vs: 188v
    188 / -75 / 115 / N/A / 165

    Seems to be a slightly different order here. Va and Vs test good, i have -74.7v on Vy so that's good too. Vsc reads 40 volts. Can't find Vzbias, and i'd have to pull the main board housing to get to more test points on the Ysus.

    I have the service manual but it doesn't seem to have the schematics for the sustain boards.
    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

    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK

      #62
      Re: Plasma 42V7 problem - please help!!!

      Schematics? For an LG? Sorry...They're unobtanium.
      Looks like you have a Vset too, but on most panels that's equal to Vs.
      Can we see a picture of the Z-sustain?
      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

      • Th3_uN1Qu3
        Believe in
        • Jul 2010
        • 6031
        • Romania

        #63
        Re: Plasma 42V7 problem - please help!!!

        Don't have my camera with me now, i'll take pics of the TV tomorrow. This is the board: http://www.ebay.co.uk/itm/42-LG-PLAS...item41732003e1
        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

        • tom66
          EVs Rule
          • Apr 2011
          • 32560
          • UK

          #64
          Re: Plasma 42V7 problem - please help!!!

          Nicer pic
          http://flattvparts.co.uk/bmz_cache/a....3000x1668.jpg

          Measure Vzbias with one probe on ground/chassis, other probe on tab of fet Q3. Voltage across R23 may work too.
          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

          • Th3_uN1Qu3
            Believe in
            • Jul 2010
            • 6031
            • Romania

            #65
            Re: Plasma 42V7 problem - please help!!!

            Tab of Q3 reads 164.4v.
            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

            • tom66
              EVs Rule
              • Apr 2011
              • 32560
              • UK

              #66
              Re: Plasma 42V7 problem - please help!!!

              Seems fine then.
              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

              • tom66
                EVs Rule
                • Apr 2011
                • 32560
                • UK

                #67
                Re: Plasma 42V7 problem - please help!!!

                You can also check ERC functionality. The voltage across caps like C6, C7, C8 (row of red caps) should measure from 1/3 Vs to 2/3 Vs, and should be nearly the same (I'd say +/-5V) on both boards. The caps are all in parallel you need only check one.
                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

                • Th3_uN1Qu3
                  Believe in
                  • Jul 2010
                  • 6031
                  • Romania

                  #68
                  Re: Plasma 42V7 problem - please help!!!

                  Thanks. I've left the shop, will check those caps tomorrow. I would also appreciate some pointers on where to scope.
                  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

                  • tom66
                    EVs Rule
                    • Apr 2011
                    • 32560
                    • UK

                    #69
                    Re: Plasma 42V7 problem - please help!!!

                    On the Z-sus, the orange bead near the output.
                    Y-sus I'd need a picture to tell you for sure but probably one of the metal plates connecting to the Y-buffer.
                    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

                    • Th3_uN1Qu3
                      Believe in
                      • Jul 2010
                      • 6031
                      • Romania

                      #70
                      Re: Plasma 42V7 problem - please help!!!

                      Here's a pic of the Ysus. And here's the waveforms of the Zsus at the orange bead near the two large inductors, i suppose that's the one you were referring to. 100v/div, TV trigger. First pic is 1ms/div, second 2ms/div.

                      Waveform is the same at the blue cap you asked the OP to check.
                      Attached Files
                      Last edited by Th3_uN1Qu3; 05-13-2013, 05:13 AM.
                      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

                      • tom66
                        EVs Rule
                        • Apr 2011
                        • 32560
                        • UK

                        #71
                        Re: Plasma 42V7 problem - please help!!!

                        The waveform from the Z-sustain looks good. The Vzbias is being applied (lower, static portion) and the panel is being sustained (higher, oscillating portion.)

                        As for the Y-sustain, I think you should test at B32.

                        Also, test the voltage across those caps I mentioned previously. One end of them is grounded, so you can just try and find the positive with your meter's COM attached to the chassis.
                        Last edited by tom66; 05-13-2013, 05:35 AM.
                        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

                        • Th3_uN1Qu3
                          Believe in
                          • Jul 2010
                          • 6031
                          • Romania

                          #72
                          Re: Plasma 42V7 problem - please help!!!

                          I think i found a problem.

                          Red caps on Zsus read 92.9v
                          Red caps on Ysus read 6.08v.

                          Also, it might be my imagination, but the waveform of the Ysus seems to have dropped in amplitude. I tested it about 20 minutes ago, but didn't take a pic then. It looked something like the OP's waveform.

                          Now, it's lower in amplitude, and there's a hiss noise at regular intervals. When the noise occurs, the waveform spikes (to the amplitude it should've had?), and i can't catch it. Here's how it looks now, when it's stable. 2ms/div, 50v/div. So... ordering an Ysus already?
                          Attached Files
                          Last edited by Th3_uN1Qu3; 05-13-2013, 06:15 AM.
                          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

                          • tom66
                            EVs Rule
                            • Apr 2011
                            • 32560
                            • UK

                            #73
                            Re: Plasma 42V7 problem - please help!!!

                            Sounds like a bad IPM. Swap the IPM or the Y-sustain.

                            You need to take a longer shot at 10ms/div using a long exposure on the camera so we can see if there are any ramp or set up waves.
                            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

                            • Th3_uN1Qu3
                              Believe in
                              • Jul 2010
                              • 6031
                              • Romania

                              #74
                              Re: Plasma 42V7 problem - please help!!!

                              There USED TO BE a ramp when i first measured. No longer.
                              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

                              • tom66
                                EVs Rule
                                • Apr 2011
                                • 32560
                                • UK

                                #75
                                Re: Plasma 42V7 problem - please help!!!

                                You should check if those transistors are still warm, if not then check the transistors on there for shorts or replace the whole Y-sus. The buffer may be OK, check with DMM using this method, use the middle pad on each buffer board, not the far pad for your return pad. http://www.youtube.com/watch?v=51SZsfH60EY
                                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

                                • Th3_uN1Qu3
                                  Believe in
                                  • Jul 2010
                                  • 6031
                                  • Romania

                                  #76
                                  Re: Plasma 42V7 problem - please help!!!

                                  The two transistors are no longer warm since the waveform changed.

                                  I'm going to check the buffers some other day. We phoned the owner before i left the shop, and he can't be bothered to come pick it up (we told him it isn't worth fixing), so it's ours to keep. Hence we'll be taking the cheaper route... I'm going to order an IPM and once it arrives, i'll resume troubleshooting.
                                  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

                                  • Clydeuk
                                    Senior Member
                                    • Jan 2012
                                    • 193

                                    #77
                                    Re: Plasma 42V7 problem - please help!!!

                                    I've successfully flashed these 29LV320 ROM's now with an external "willem" type programmer (a cheap chinese copy). I thought it wasn't working but realised I was using the wrong file and also needed to do a temporary sector unprotect. The 42V7 I have does not match any of the LG files, I only got display back after flashing the original back in (good job I saved it first!).

                                    The other one is a 42V8A panel with minor discharge at the top (worse when cold and only noticeable on dark scenes (seems worse on blue), it's also at worst in the top corners. I flashed the update rom into this after trying panel setup, but it has appeared to make no difference. I can tweak out the sparkles but then get dark specks instead. I suspect it's the panel to blame, I'm sure there must be some way to alter things. I might check the caps though I'm not convinced, it made no difference on my other one.

                                    Comment

                                    Related Topics

                                    Collapse

                                    • KYBOSH
                                      Hitachi 55HDS69 55" Plasma TV - No Picture But Sound
                                      by KYBOSH
                                      Picked up a bahemoth plasma TV not too long ago and just now getting around to looking at it.
                                      No picture but you hear the TV static (white noise) playing loud and clear.
                                      The back was already taken off (and no screws were provided) as the previous owner had already taken a look.
                                      But it seems they didn't get too far and just left it.

                                      When I first took a look I was amazed at how pristine the inside looked.
                                      Its as if the TV had been in a time capsule.
                                      Caps looked like they were just pulled off the self.
                                      Copper coils had no sign of corrosion on...
                                      02-01-2023, 11:10 PM
                                    • KYBOSH
                                      Trying to Save - LG 60PH6700 60-inch plasma HDTV - Powers ON but no picture
                                      by KYBOSH
                                      Saved this beast from the landfill this weekend.
                                      Manfactured July 2013 in Mexico.

                                      I love working on plasma TVs.
                                      Its been a while but I was lucky enough to find 2 this week.

                                      The TV powers on and stays on but no picture. Havent checked for sound yet.
                                      No bulging caps although the insides are pretty dusty and the boards are discolored from many years of high heat.
                                      Will start troubleshooting tonight.

                                      ...
                                      10-17-2024, 01:17 PM
                                    • 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
                                    • Loading...
                                    • No more items.
                                    Working...