Sharp LC-47SB57UT will not power on

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #61
    Re: Sharp LC-47SB57UT will not power on

    Regarding your problem, can you check the voltage across those 100uF/10uF startup caps?
    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

    • johnboy1313
      Badcaps Legend
      • Nov 2012
      • 1959
      • USA

      #62
      Re: Sharp LC-47SB57UT will not power on

      will do

      Comment

      • johnboy1313
        Badcaps Legend
        • Nov 2012
        • 1959
        • USA

        #63
        Re: Sharp LC-47SB57UT will not power on

        100uf 50v = 16.2v
        10uf 100v = 15.5v

        Comment

        • johnboy1313
          Badcaps Legend
          • Nov 2012
          • 1959
          • USA

          #64
          Re: Sharp LC-47SB57UT will not power on

          Can I use a computer psu to apply the 12v/24v to the appropriate pins?

          Comment

          • johnboy1313
            Badcaps Legend
            • Nov 2012
            • 1959
            • USA

            #65
            Re: Sharp LC-47SB57UT will not power on

            I've been doing some reading and it looks like using a computer PSU is out of the question. I wish i could identify the fault with this one.

            Comment

            • tom66
              EVs Rule
              • Apr 2011
              • 32560
              • UK

              #66
              Re: Sharp LC-47SB57UT will not power on

              Connected to one of the caps there should be a resistor. Does this resistor test good? (Should be <100 ohms.)
              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

              • johnboy1313
                Badcaps Legend
                • Nov 2012
                • 1959
                • USA

                #67
                Re: Sharp LC-47SB57UT will not power on

                I'm not really sure which resistor is the one you are referencing. The only one that measures less than 100 ohms is JR905 (if that is a resistor) which measures 00.8 ohms when the DMM is set to 200 ohms.

                *Edit* C927 and C928 are the caps I replaced, if you can't tell.
                Attached Files

                Comment

                • tom66
                  EVs Rule
                  • Apr 2011
                  • 32560
                  • UK

                  #68
                  Re: Sharp LC-47SB57UT will not power on

                  That should measure zero, it is good.
                  How is D910?

                  I am fairly sure it is the startup section or a shorted output.
                  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

                  • johnboy1313
                    Badcaps Legend
                    • Nov 2012
                    • 1959
                    • USA

                    #69
                    Re: Sharp LC-47SB57UT will not power on

                    Originally posted by ben7
                    The 0.79v on the 12v rail is odd. It could be a short on the mainoard.

                    If it is still like that when the PSU is powered on, while disconnected from the chassis, then there is an issue with the PSU.
                    Originally posted by tom66
                    That should measure zero, it is good.
                    How is D910?

                    I am fairly sure it is the startup section or a shorted output.
                    Do you think ben was on to something? Maybe the .79V on the 12V rail while in standby is due to a short on the output.

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA

                      #70
                      Re: Sharp LC-47SB57UT will not power on

                      OK, I went back and read the voltage readings, you are getting all the correct signals (BL_ON: ON/OFF, and PS_ON) from the main board, but the 12v shows almost 0 and no 24VDC either which means that the transformer for the 12v/24v (both of these voltages are generated by the same transformer).
                      So you need to check the DC voltage on that large 450VDC caps C907, C908 on the two legs of the cap, it should have about 380~390VDC on it when you hit the power switch on the TV.
                      Last edited by budm; 12-19-2012, 07:57 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

                      • johnboy1313
                        Badcaps Legend
                        • Nov 2012
                        • 1959
                        • USA

                        #71
                        Re: Sharp LC-47SB57UT will not power on

                        I will check them although nothing happens when I hit the power switch. I'm used to hearing components on power supplies make noises when plugged in and again when powered on. This one does neither. According to the trouble shooting guide, BD901 should have 320V at the output prior to power on and 400V after. I found BD901, it's a D10XB60 rectifier. I'm just not sure which leg is the output.
                        Last edited by johnboy1313; 12-19-2012, 08:38 PM.

                        Comment

                        • johnboy1313
                          Badcaps Legend
                          • Nov 2012
                          • 1959
                          • USA

                          #72
                          Re: Sharp LC-47SB57UT will not power on

                          I checked BD901, C907, and C908. When checking across + and - of the rectifier, and both caps, I get 168V on all three. When checking each of the four legs on the rectifier against ground individually, starting at + and working my way up, I get
                          7.5V
                          0.0V
                          0.0V
                          2.0V

                          The trouble shooting guide says when following "NO" to whether or not BD901 has 320V,
                          "Does the PFC circuit operate normally? (L904, Q904, D902, IC904 and etc. And, the circuit around the protection circuit etc. is checked.)"

                          I'm still getting up to speed on the diagram. This will probably take me a while.
                          Attached Files
                          Last edited by johnboy1313; 12-19-2012, 08:54 PM.

                          Comment

                          • budm
                            Badcaps Legend
                            • Feb 2010
                            • 40746
                            • USA

                            #73
                            Re: Sharp LC-47SB57UT will not power on

                            First, when you work on the hot side of the power supply, you need to use the negative leg of that 450V cap as the ground ref point, not the chassis of the TV, and be real careful since the hot side is deadly so do not touch any thing in the hot section with your body.
                            OK, the PFC Voltage boosting circuit is not working.
                            As you can see, the PS_ON (>2.5v) signal is fed into R953 which turn on Q908 which causes the LED in the OPTOISOLATOR IC904 to be on which turns on the Phototransistor on the receiving side of the IC904, this will turn on switched transistor Q906 which allows the VCC (generated by the AUX winding of the 5VSTBY transformer, this VCC is also used for running the 5VSTBY SMPS IC) at the Collector of Q906 to appear at the Emitter of the Q906 (there will be small voltage drop acoss Emitter/Collector). This voltage is used to run the PFC Voltage Booster IC901. So that is how the PFC is turn on. The 12v/24v required that boosted voltage (320V) to operate.
                            C909 is the filter cap for the PFC VCC pin7, so check the DC voltage on that cap.
                            Report the DC voltage reading of the PFC IC pin, use Pin1 for ground.
                            Then take the DC resistance reads between the ground pin PIN1 of the PFC and all other pins of the IC and report each reading.
                            Also check C918? (cannot read the print) 1uf/25V hwich is connected to pin4 of the PFC IC.
                            Attached Files
                            Last edited by budm; 12-19-2012, 10:24 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

                            • johnboy1313
                              Badcaps Legend
                              • Nov 2012
                              • 1959
                              • USA

                              #74
                              Re: Sharp LC-47SB57UT will not power on

                              Originally posted by budm
                              First, when you work on the hot side of the power supply, you need to use the negative leg of that 450V cap as the ground ref point, not the chassis of the TV, and be real careful since the hot side is deadly so do not touch any thing in the hot section with your body.
                              OK, the PFC Voltage boosting circuit is not working.
                              As you can see, the PS_ON (>2.5v) signal is fed into R953 which turn on Q908 which causes the LED in the OPTOISOLATOR IC904 to be on which turns on the Phototransistor on the receiving side of the IC904, this will turn on switched transistor Q906 which allows the VCC (generated by the AUX winding of the 5VSTBY transformer, this VCC is also used for running the 5VSTBY SMPS IC) at the Collector of Q906 to appear at the Emitter of the Q906 (there will be small voltage drop acoss Emitter/Collector). This voltage is used to run the PFC Voltage Booster IC901. So that is how the PFC is turn on. The 12v/24v required that boosted voltage (320V) to operate.
                              Thanks for explaining that.

                              Originally posted by budm
                              C909 is the filter cap for the PFC VCC pin7, so check the DC voltage on that cap.
                              Report the DC voltage reading of the PFC IC pin, use Pin1 for ground.
                              Which pin is the PFC IC pin? Pin 7?

                              Originally posted by budm
                              Then take the DC resistance reads between the ground pin PIN1 of the PFC and all other pins of the IC and report each reading.
                              Also check C918? (cannot read the print) 1uf/25V hwich is connected to pin4 of the PFC IC.
                              That's C911. The writing is burried under the writing for R977, 100K OHM 1/8W.

                              Comment

                              • johnboy1313
                                Badcaps Legend
                                • Nov 2012
                                • 1959
                                • USA

                                #75
                                Re: Sharp LC-47SB57UT will not power on

                                At 20k ohms on the meter,
                                Pin 1 - 8 = 9.98
                                1 - 7 = overload
                                1 - 6 = 11.07
                                1 - 5 = overload
                                1 - 4 = overload
                                1 - 3 = 0.23
                                1 - 2 = overload

                                Voltage across C909 = 0.1v

                                Voltage at every pin on IC901 is 0.1V except pin 6 which is 1.3V

                                Comment

                                • budm
                                  Badcaps Legend
                                  • Feb 2010
                                  • 40746
                                  • USA

                                  #76
                                  Re: Sharp LC-47SB57UT will not power on

                                  What DC voltage you get at the Collector (VCC) of Q906? This VCC is from what you read earlier in post 63.
                                  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

                                  • johnboy1313
                                    Badcaps Legend
                                    • Nov 2012
                                    • 1959
                                    • USA

                                    #77
                                    Re: Sharp LC-47SB57UT will not power on

                                    I believe I have identified the collector. According to the schematic, R921 and the collector of Q906 are connected, right?
                                    Attached Files

                                    Comment

                                    • budm
                                      Badcaps Legend
                                      • Feb 2010
                                      • 40746
                                      • USA

                                      #78
                                      Re: Sharp LC-47SB57UT will not power on

                                      yes.
                                      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

                                      • johnboy1313
                                        Badcaps Legend
                                        • Nov 2012
                                        • 1959
                                        • USA

                                        #79
                                        Re: Sharp LC-47SB57UT will not power on

                                        0.0v at the collector

                                        Comment

                                        • tom66
                                          EVs Rule
                                          • Apr 2011
                                          • 32560
                                          • UK

                                          #80
                                          Re: Sharp LC-47SB57UT will not power on

                                          Measured relative to negative lead of big cap?
                                          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

                                          • advant
                                            Driving a Sharp TCON/panel with a universal main board
                                            by advant
                                            This thread is about trying to get an Universal Main Board to work with a Sharp TCON and panel.

                                            I have a Sharp LC-46D85UN TV that has had a main board issue. Since this model is from 2009, I am not able to find an exact replacement of the main board. Instead, I decided to see if I can future proof this tv by getting a Universal Main Board (T53U21.2) from China to work with the Sharp TCON (CPWBX4291TPZA) and panel. The universal main board supports a 8 bit dual channel LVDS interface whereas the TCON requires a 10 bit dual channel LVDS input. I have modded the LVDS connector to match...
                                            02-03-2020, 12:25 AM
                                          • sefoster
                                            Sharp Aquos Lc-80LE757U flashing Sharp on screen when plugged in
                                            by sefoster
                                            I have a Sharp Aquos LC-80LE757U that randomly made a loud popping noise when when watching TV one day. We found that the fuse blew and the thermistor. We ended up replacing the entire power supply board and have also replaced the TCON board. Now as soon as I plug the TV in it lights up and has the Sharp logo flashing on and off of the screen. If I unplug the ribbon cable from the TCON board to the main board I get the 2 long 5 short error code. Any ideas on where to go from here? We've tried resetting it but nothing has worked. If we plug it in and let it cycle through the flashing of the Sharp...
                                            11-20-2022, 09:29 AM
                                          • SONY_E-WASTER
                                            Help! Sharp LC-70UE30U 3 long flashes + 3 short flashes.
                                            by SONY_E-WASTER
                                            Hello, I'm new to this forum. I like to tinker with Sony electronics, I have been lucky trouble shooting sony stuff, But I can't find much info on this Sharp TV.

                                            The problem; plug to power>white led power indicator light is on>it turns on to the red Sharp logo>
                                            then the android logo is displayed, lit fine then the android logo brightness varies, then lit normal, then the tv restarts and does the same startup logos over and over for 5 times then it turns off and the power indicator light flashes the trouble code 3 long blinks plus 3 short blinks .

                                            does...
                                            12-26-2021, 05:46 PM
                                          • gavenb
                                            Sharp LC-80LE661U 80 inch
                                            by gavenb
                                            Hi folks!
                                            I have a LC-80LE661U that had some interesting issues.
                                            Initially, it would come on and show the sharp logo and would show normal static before shutting off.

                                            I started troubleshooting by disconnecting the led lighting strips and turning it on. It would do the same thing - come on, show the sharp logo and shut off. After reading, it was suggested to replace the main board. That was replaced and the same symptoms resulted. After this and some reading, the parts cannon got loaded up. I replaced the power board, same issue. Replaced the Tcon board and now it...
                                            11-12-2023, 02:05 PM
                                          • Superbee_dad
                                            Sharp 80” long short flash backlight error - Help
                                            by Superbee_dad
                                            Hello Sharp TV experts
                                            Our Sharp LC-80LE642U displays one short one long flash error code which is a backlight error. I went into service mode and there were 8 lamp error counts recorded. I reset the count to 0 and did a reset. The last monitor error cause was 16 B00014639:12. 16 is the code for backlight error. I tried to power the tv up but went back into error mode.

                                            > I checked voltages on the power supply board and they all check out .. including 3.28 volts at the error pin.
                                            > There is power to the cpu and T-CONN and no faults found there. The cpu has a flashing...
                                            01-24-2025, 11:51 PM
                                          • Loading...
                                          • No more items.
                                          Working...