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    Samsung un32eh5000f No backlight.

    Samsung un32eh5000f No backlight Can see picture with flashlight.

    I'm new to working on LED's fixed plenty of other stuff already.


    Powers going to LED
    CNL 802

    Pin 1 149.5 VDC
    Pin 2 128.2 VDC
    Pin 3 Not used
    Pin 4 128.2 VDC
    Pin 5 0.343 VDC

    What should I expect ?
    Any way to test the LED strips ?

    Thank You
    Chris
    Attached Files

    #2
    Re: Samsung un32eh5000f No backlight.

    You have open LED sting that is connected between pin 4 and pin 5.
    Samsung BN44-00665A (L32GF_DSM) Power Supply / LED Board
    Last edited by budm; 01-06-2018, 08:16 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


      #3
      Re: Samsung un32eh5000f No backlight.

      I was thinking open circuit with the readings.. Is there anyway to bench test them ?

      What voltage should I expect, I couldn't find a schematic or service manual for it...

      Comment


        #4
        Re: Samsung un32eh5000f No backlight.

        Right now you are getting 149.5V on pin 1 which is the Anode of the whole LED string, pin 5 is the Cathode return of the whole LED string.
        If you look at the Voltage chart as printed on the board, you will see LED Voltage of around 90V with load.
        You will have to open up the LCD panel assembly to get to the LED strips to test each one to see which one has open circuit. You will have to test each LED on the failed strip to find out which one/ones is/are bad.
        There are more than one version of the LCD panels used in this model, so you must verify what you have.
        http://www.shopjimmy.com/catalogsear...ng+un32eh5000f
        Fail LEDs are very common failure, when you get it fix make sure you turn down the backlights level.
        Last edited by budm; 01-06-2018, 11:21 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


          #5
          Re: Samsung un32eh5000f No backlight.

          Testing and fixing the LEDs is quite easy and inexpensive but watch carefully when you dissassemble and reassemble the panel. Due to the fact the panel has no screws but only pop-up tabs on the plastic surrounding the LCD, it is is difficult to open and necessitates to put force on the frame for dissassembling. Worse is reassembling as each of the frame tabs must be pushed toward LCD to be locked, again it is necesary to apply important force and the tabs click strongly agin the panel. So, last week, one fixed screen broke by itself without any mechnical strenght or move of the set two days after fixing. I imagine the lcd was broken on the edge for a few 1/10 inchbefore being broken on several inches on the high left hanside corner, probably due to temperature changes. Too bad they switched from screwed metallic panel frames to plastic clipsed system !

          Comment


            #6
            Re: Samsung un32eh5000f No backlight.

            http://forum.iwenzo.de/grundig-servi...e--t61847.html

            see also here

            Comment


              #7
              Re: Samsung un32eh5000f No backlight.

              Thanks for the explanation on the voltages, I had the feeling it was the strips... Disassembly was a bit of a pain, thank god it wasn't a bigger panel... There might be firmware update to address the LED life issue, but I will turn them down....

              Comment


                #8
                Re: Samsung un32eh5000f No backlight.

                My Samsung UN32EH5000F is having a very similar problem. Rather than NO backlight, I have a very dim picture. I don't need to use a flashlight to see the picture, but can just see it in the ambient light of my bedroom, which is far from well lit. It does occasionally flicker, getting ever so slightly brighter or dimmer, but it is way too dim to be of any use. Adjusting the backlight setting has no effect. So I replaced the T-CON board after reading that it's a common problem with the backlight and it was only 12 bucks with shipping. Symptom did not change. So now I'm thinking the PS board and not the LED strips since there is some bit of brightness. If it was a bad LED, my understanding is the screen would be totally black. Does this sound correct? Thanks for any thoughts you may have.

                Roy

                Comment


                  #9
                  Re: Samsung un32eh5000f No backlight.

                  @ Roy, Test connector from mainboard to powerboard on powerboard side, sholud be a little legend/map of expected voltages, test with tv plugged in but off then hit power, report both conditions here, give pin number, pin description and condition on and off, demonstration in signature below.
                  Last edited by nomoresonys; 02-26-2019, 09:44 AM.

                  Comment


                    #10
                    Re: Samsung un32eh5000f No backlight.

                    You most likely need full LED strip replacement. Samsungs do not have protection to shut offf the LED supply so backlights will continue to burn out until the screen is dim. You can force the backlight on by unplugging the cable between the main and power supply board. Fairly simple to remove the panel on a 32 inch TV but you still need to be careful. Lower the backlight level on all inputs and all smart apps to around 60 to 70 after replacement.

                    Comment


                      #11
                      Re: Samsung un32eh5000f No backlight.

                      Thanks guys; I'll open her back up this evening when I get home from work and check things out.

                      -Roy

                      Comment


                        #12
                        Re: Samsung un32eh5000f No backlight.

                        check out this thread: https://www.badcaps.net/forum/showth...ung+ue32eh5000
                        Also perform main board disconnect to see what will happen to backlights.
                        Last edited by budm; 02-26-2019, 04:17 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


                          #13
                          Re: Samsung un32eh5000f No backlight.

                          With TV plugged in, but OFF:

                          Pins 1-13 (odd) No voltage

                          I didn't measure 2-14 because pins were inaccessible.

                          With TV ON:

                          Pin Label Voltage

                          1 B13 13 VDC
                          3 B13 13 VDC
                          5 Vamp 13 VDC
                          7 Vamp 13 VDC
                          9 GND 0 V
                          11 B5V 5.2 VDC
                          13 B5V 5.2 VDC

                          Pin Label Voltage

                          2 PWM 1 VDC
                          4 B13 13 VDC
                          6 BLU 4.8 VDC
                          8 GND 0 V
                          10 GND 0 V
                          12 A5V 5.2 VDC
                          14 PS 3.5 VDC


                          I had to unscrew and flip the board over to measure the even pins, taking great care not to short the pins with the probe tip.

                          -Roy

                          Comment


                            #14
                            Re: Samsung un32eh5000f No backlight.

                            Did you unhook cable from mainboard to powerboard, see if backlights come on and stay on? as suggested in post #10.
                            Last edited by nomoresonys; 02-27-2019, 09:30 AM.

                            Comment


                              #15
                              Re: Samsung un32eh5000f No backlight.

                              I unhooked mainboard from power board while TV was powered down, and TV would not turn on in that condition. Should I have unhooked them while TV was powered on?

                              Comment


                                #16
                                Re: Samsung un32eh5000f No backlight.

                                No, you did it right.

                                Comment


                                  #17
                                  Re: Samsung un32eh5000f No backlight.

                                  Originally posted by ossroy View Post
                                  With TV plugged in, but OFF:

                                  Pins 1-13 (odd) No voltage

                                  I didn't measure 2-14 because pins were inaccessible.

                                  With TV ON:

                                  Pin Label Voltage

                                  1 B13 13 VDC
                                  3 B13 13 VDC
                                  5 Vamp 13 VDC
                                  7 Vamp 13 VDC
                                  9 GND 0 V
                                  11 B5V 5.2 VDC
                                  13 B5V 5.2 VDC

                                  Pin Label Voltage

                                  2 PWM 1 VDC
                                  4 B13 13 VDC
                                  6 BLU 4.8 VDC
                                  8 GND 0 V
                                  10 GND 0 V
                                  12 A5V 5.2 VDC
                                  14 PS 3.5 VDC


                                  I had to unscrew and flip the board over to measure the even pins, taking great care not to short the pins with the probe tip.

                                  -Roy
                                  You can use skinny probe tip to access the Even number pin via the wire entrance of the connector.

                                  What does not make any sense to me is that you reported " Rather than NO backlight, I have a very dim picture" but you also report "Pins 1-13 (odd) No voltage". If B13V is not working then the T-CON cannot be working either.
                                  Last edited by budm; 02-27-2019, 04:35 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


                                    #18
                                    Re: Samsung un32eh5000f No backlight.

                                    Originally posted by ossroy View Post
                                    I unhooked mainboard from power board while TV was powered down, and TV would not turn on in that condition. Should I have unhooked them while TV was powered on?
                                    When you unhook the cable between the main board and the power supply board then plug the TV into the outlet, that will put the power supply and backlights driver circuits into self-test mode (it the board has pull-up resistors), so if the power supply, LED driver circuits, and the LED strings are OK then the backlights should come on and stay on as long as the TV is plugged in.
                                    At this point you need to report the Voltage on the power supply connector that goes to the main board and also at the LED connector (LED connector in place).

                                    BTW: Line Voltage: 170V P-P @ 16.6ms. That should be 120 V RMS X 2.828 = 339.36 V P-P.
                                    Last edited by budm; 02-27-2019, 05:13 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


                                      #19
                                      Re: Samsung un32eh5000f No backlight.

                                      Originally posted by budm View Post
                                      You can use skinny probe tip to access the Even number pin via the wire entrance of the connector.

                                      What does not make any sense to me is that you reported " Rather than NO backlight, I have a very dim picture" but you also report "Pins 1-13 (odd) No voltage". If B13V is not working then the T-CON cannot be working either.
                                      I didn't have any skinny probe tips, so I just ordered a set from Amazon this morning.

                                      As far as the No Voltage on pins 1-13 (odd), that was when the TV was plugged in but turned off. As shown above, I did have 13V on pins 1, 3, 5 and 7 when the TV was turned on. Or should have I have seen voltage there with the TV turned off as well?


                                      -Roy

                                      Comment


                                        #20
                                        Re: Samsung un32eh5000f No backlight.

                                        Originally posted by budm View Post
                                        When you unhook the cable between the main board and the power supply board then plug the TV into the outlet, that will put the power supply and backlights driver circuits into self-test mode (it the board has pull-up resistors), so if the power supply, LED driver circuits, and the LED strings are OK then the backlights should come on and stay on as long as the TV is plugged in.
                                        At this point you need to report the Voltage on the power supply connector that goes to the main board and also at the LED connector (LED connector in place).
                                        I will have to try again tonight. I had other obligations last night and never got a chance to look at the TV, and now I'm second guessing myself on what all happened on Tuesday.

                                        Originally posted by budm View Post
                                        BTW: Line Voltage: 170V P-P @ 16.6ms. That should be 120 V RMS X 2.828 = 339.36 V P-P.
                                        Now that's embarrassing! I used the formula for Peak and then wrote P-P.

                                        Comment

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