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HANNS G HZ281 White Screen

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    #21
    Re: HANNS G HZ281 White Screen

    Oh, that's a nice spreadsheet - thanks for the pointer. It indicates the tcon board is bad, but to check the panel first before replacing the tcon board. I'll search around the forum for how to do that.
    Attached Files

    Comment


      #22
      Re: HANNS G HZ281 White Screen

      Well, I'm not sure how to test the panel itself - I jiggled all the ribbon cables to the driver boards with no effect. Looks like there is no availability for this tcon board, so I'll need to attempt to diagnose and repair the one I have. The u102 transistor (circled in red) measures 7.3k Ohms middle to right leg, and 100 Ohms middle to left leg.
      Attached Files

      Comment


        #23
        Re: HANNS G HZ281 White Screen

        Originally posted by rrflorida View Post
        The u102 transistor (circled in red) measures 7.3k Ohms middle to right leg, and 100 Ohms middle to left leg.
        Good find.
        But left leg is the input, so 100 Ohms is not necessarily a problem.
        That said, see what voltage is coming to the left leg of U102 (with respect to ground) and what voltage it is outputting on its right leg (again, with respect to ground).

        Also, could you please tell us what part number is written on U102?

        Comment


          #24
          Re: HANNS G HZ281 White Screen

          That is Voltage regulator IC, not transistor. See what Voltage you have on Vin and Vout pin.
          I suspect the GAMMA Voltages are generated by U300, 301, get the P/N on both of them.
          BTW, designator for Transistor is 'Q??', IC is U??







          .
          Last edited by budm; 09-04-2018, 03:16 PM.
          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


            #25
            Re: HANNS G HZ281 White Screen

            momaka and budm - thanks for the responses, really appreciate the help! I will gather the requested info Monday. Sorry for the delayed reply, was out of town.

            randy

            Comment


              #26
              Re: HANNS G HZ281 White Screen

              U102 is a 960T45. Left leg is 4.96V, right leg is 3.24V
              U300 and U301 are both BUF 07704, which Mouser says is a LCD Gamma Buffer.

              Comment


                #27
                Re: HANNS G HZ281 White Screen

                Originally posted by rrflorida View Post
                U102 is a 960T45. Left leg is 4.96V, right leg is 3.24V
                U300 and U301 are both BUF 07704, which Mouser says is a LCD Gamma Buffer.
                960T45 is 3.3V regulator, it is OK. https://cdn.badcaps-static.com/pdfs/...2741533542.pdf
                GAMMA chips may be bad, need to look up spec sheet.
                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


                  #28
                  Re: HANNS G HZ281 White Screen

                  Data sheet for BUF 07704 attached
                  Attached Files

                  Comment


                    #29
                    Re: HANNS G HZ281 White Screen

                    So now you have the spec sheet of the IC showing what each pin is for, start checking the Voltages and report the reading for each pin, that will be a starting point.
                    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


                      #30
                      Re: HANNS G HZ281 White Screen

                      Below and attached (the formatting is messed up here in the post) are the voltage readings from the BUF07704 chips. The OUT side seems to correlate pretty well with the IN side.



                      Pin U301 U302 Name
                      1 13.13 0 VDD
                      2 12.46 6.55 OUT1
                      3 10 5.31 OUT2
                      4 9.29 4.34 OUT3
                      5 8.9 3.78 OUT4
                      6 8.11 3.07 OUT5
                      7 6.76 0.64 OUT6
                      8 0.12 0 NC
                      9 5.47 7.21 OUTCOM
                      10 0 0 GND
                      11 0 0 GND
                      12 5.45 0.63 INCOM
                      13 0.76 0.65 NC
                      14 6.75 0.64 IN6
                      15 8.11 3.07 IN5
                      16 8.89 3.78 IN4
                      17 9.29 4.34 IN3
                      18 9.99 5.31 IN2
                      19 12.45 6.56 IN1
                      20 13.13 13.14 VDD

                      Attached Files
                      Last edited by rrflorida; 09-12-2018, 01:11 PM.

                      Comment


                        #31
                        Re: HANNS G HZ281 White Screen

                        https://www.badcaps.net/forum/attach...3&d=1536778904
                        Look at INCOM and OUTCOM of U302: U301 INCOM is 5.45V, OUTCOM is 5.47CV, but U302 INCOM is 0.63V and the OUTCOM is 7.21V
                        Look at pin 1 of U301 and 302: 0V on U302?
                        Last edited by budm; 09-13-2018, 10:31 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


                          #32
                          Re: HANNS G HZ281 White Screen

                          Oh, I messed up pin 1 on U302 (VDD) - it's actually 13.13V, so ok there.

                          I see what you are saying on INCOM/OUTCOM on U302. I just double checked:
                          12 INCOM: .64 steady
                          9 OUTCOM: climbs from 1-3 volts up to 6-7 volts everytime I probe it (climbs for about 30 seconds)

                          Are you suspecting U302?

                          [NOTE: I somehow started using the wrong U numbers, but will stick with the current U301/U302 for consistency]

                          Comment


                            #33
                            Re: HANNS G HZ281 White Screen

                            Yes, I expect U302 to behave the same as U301, it is buffer after all.
                            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


                              #34
                              Re: HANNS G HZ281 White Screen

                              Ok, I will attempt to replace the chip and report back. Thanks.

                              Comment


                                #35
                                Re: HANNS G HZ281 White Screen

                                fyi - having trouble finding the part - Mouser just cancelled the order and said it is discontinued. More later..

                                Comment


                                  #36
                                  Re: HANNS G HZ281 White Screen

                                  Maybe check with eBay. Sure there's a chance the part you get may not be genuine or high quality, but it could work fine. I've bought PWM controllers for motherboards before, and they worked okay. It's really only the high-power devices (MOSFETs, BJTs, and those STK stereo modules) that you want to either stay away from or use with lots of caution.
                                  That, and the slow wait for the part to arrive from the far factories and shops of East Asia.
                                  Last edited by momaka; 10-05-2018, 05:08 PM.

                                  Comment


                                    #37
                                    Re: HANNS G HZ281 White Screen

                                    Doesn't look like any reliable retailers have it available in small order quantities https://octopart.com/search?q=buf07704&start=0

                                    but you can get a single BUF07704 chip here
                                    Probably not the real thing, but like momaka says, it may work well enough.

                                    Let us know how it goes, I could be in the market for one myself soon

                                    Comment


                                      #38
                                      Re: HANNS G HZ281 White Screen

                                      I ended up using eBay seller dicikey-max. We'll know more in 12-50 days.... Thanks for the suggestions

                                      https://www.ebay.ie/itm/332274532555...m=332274532555

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