Samsung LN19B361C5D Backlight, No Picture/Sound

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  • caphair
    Badcaps Legend
    • Nov 2011
    • 1249
    #1

    Samsung LN19B361C5D Backlight, No Picture/Sound

    I have here a friend's Samsung that when plugged in, backlight instantly turns on without picture or sound, also no led light on the front (not sure if that's how it'd be if this was turned on) No response when pressing power or any other buttons.

    What I've done so far:
    Checked for any bulged caps - none
    Measured PSU output voltages:
    1 - 0v
    2 - 14v
    3-5 Grounds 0v
    6 - 5.12v
    7 - 5.12v
    8 - 0v
    9 - On/Off terminal had a steady 5v no change when pressing power button

    Measured the output voltages of the 3 regulators on mainboard:
    IC109 - 5.1v In, 3.3v out, 0v ground
    IC505 - 4.95v In, 1.85 out, .60v ground (adjustable regulator)
    IC106 - This looked like it had been replaced and gave no output voltage:
    4.95v In, .06v out, 0v ground

    The part number for IC106 is a 17-33G the part number for IC109 is 17-33 which I believe was the original in place of IC106, also checked their specs and they're pretty much equivalent.

    I went ahead and ordered a 17-33 and will keep you guys posted when I replace it, I just had couple questions:

    1. Is the 14v measured where 15v should be related to the seemingly defective regulator?
    2. Would the no output of the suspected regulator cause the given problem, or would something else that's failed also cause the regulator to fail?
    2. There are smd on the main board labeled BD(numbers) what are these? They measure as short circuits when measuring ohms

    Thanks for any input, also I apologize for the blurry pics I was in a bit of a hurry, if you need clearer ones let me know.
    Attached Files
    Last edited by caphair; 12-09-2012, 09:38 AM.
    Tags: None
    • retiredcaps
      Badcaps Legend
      • Apr 2010
      • 9271
      #2
      Re: Samsung LN19B361C5D Backlight, No Picture/Sound

      Originally posted by caphair
      1. Is the 14v measured where 15v should be related to the seemingly defective regulator?
      The 15V is likely unregulated. 14V might be correct when the backlights are on.

      2. There are smd on the main board labeled BD(numbers) what are these? They measure as short circuits when measuring ohms
      BD is probably bead or ferrite bead (FB). See

      http://en.wikipedia.org/wiki/Electro...e_designations

      Thanks for any input, also I apologize for the blurry pics I was in a bit of a hurry, if you need clearer ones let me know.
      Remote troubleshooting is very difficult. The quality of the photos and the clarity of your problem description dictate, to some, whether to respond or hit close window.

      So yes, your photos could be clearer.
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        Comment

        • caphair
          Badcaps Legend
          • Nov 2011
          • 1249
          #3
          Re: Samsung LN19B361C5D Backlight, No Picture/Sound

          Thanks for your input. I'm curious, could I bridge output of the working 3.3v regulator to the suspected bad one to see if tv works?

            Comment

            • retiredcaps
              Badcaps Legend
              • Apr 2010
              • 9271
              #4
              Re: Samsung LN19B361C5D Backlight, No Picture/Sound

              Originally posted by caphair
              Thanks for your input. I'm curious, could I bridge output of the working 3.3v regulator to the suspected bad one to see if tv works?
              I have no electronic design expertise and don't know the ramifications of doing so. Thus, I would say don't do it.

              If you can't wait for your part to arrive, try looking through your junk boards for a 1117-33 regulator. These parts are fairly common on many boards.
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                Comment

                • caphair
                  Badcaps Legend
                  • Nov 2011
                  • 1249
                  #5
                  Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                  Yeah I couldn't find any only 1.8v regulators. I'll wait for new part and keep you posted on results after replacing.

                    Comment

                    • caphair
                      Badcaps Legend
                      • Nov 2011
                      • 1249
                      #6
                      Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                      Ok replaced the regulator, I now have 3.3v output from it but my symptom has changed to a blinking standby light.

                      I re-measured input voltages to regulators and they now fluctuate from 4.40-4.65v. I back measured available voltages to the psu and only the 15v connector is also fluctuating but with the connector to main board unplugged the 15v measures a steady 17v. Any ideas?
                      Last edited by caphair; 12-12-2012, 03:23 PM.

                        Comment

                        • retiredcaps
                          Badcaps Legend
                          • Apr 2010
                          • 9271
                          #7
                          Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                          Originally posted by caphair
                          I re-measured input voltages to regulators and they now fluctuate from 4.40-4.65v. I back measured available voltages to the psu and only the 15v connector is also fluctuating but with the connector to main board unplugged the 15v measures a steady 17v. Any ideas?
                          Fluctuating voltages are never good. They should all be steady.

                          I suggest measuring the large filter capacitor to make sure it is a steady DC voltage. Caution, it is high voltage. If you are in the USA, it should be around 165V DC. If PFC is involved, it might be close to 400V DC.

                          Report your reading.
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                            Comment

                            • caphair
                              Badcaps Legend
                              • Nov 2011
                              • 1249
                              #8
                              Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                              It measures a fluctuation of 165-166v and with main board disconnected it measures fluctuation of 170-171v

                                Comment

                                • retiredcaps
                                  Badcaps Legend
                                  • Apr 2010
                                  • 9271
                                  #9
                                  Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                  Originally posted by caphair
                                  It measures a fluctuation of 165-166v and with main board disconnected it measures fluctuation of 170-171v
                                  Put a fresh battery in your multimeter and retest.
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                                    Comment

                                    • tom66
                                      EVs Rule
                                      • Apr 2011
                                      • 32560
                                      • UK
                                      #10
                                      Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                      Those readings look fine to me -- it's quite normal for the capacitor to measure a little high under no load.
                                      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

                                        • caphair
                                          Badcaps Legend
                                          • Nov 2011
                                          • 1249
                                          #11
                                          Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                          So what should I try now? I also tested the "b-dim" output from psu and it fluctuates 3.8-3.95v there is no voltage measured from "a-dim" connector

                                            Comment

                                            • tom66
                                              EVs Rule
                                              • Apr 2011
                                              • 32560
                                              • UK
                                              #12
                                              Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                              Try Info-Menu-Mute-Power on remote control then access Factory Reset if the menu appears.
                                              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

                                                • caphair
                                                  Badcaps Legend
                                                  • Nov 2011
                                                  • 1249
                                                  #13
                                                  Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                                  Originally posted by tom66
                                                  Try Info-Menu-Mute-Power on remote control then access Factory Reset if the menu appears.
                                                  Don't have the remote unfortunately

                                                    Comment

                                                    • tom66
                                                      EVs Rule
                                                      • Apr 2011
                                                      • 32560
                                                      • UK
                                                      #14
                                                      Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                                      Do you have any remote for any Samsung product? They are more or less interchangeable.
                                                      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

                                                        • caphair
                                                          Badcaps Legend
                                                          • Nov 2011
                                                          • 1249
                                                          #15
                                                          Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                                          Originally posted by tom66
                                                          Do you have any remote for any Samsung product? They are more or less interchangeable.
                                                          No I don't

                                                            Comment

                                                            • caphair
                                                              Badcaps Legend
                                                              • Nov 2011
                                                              • 1249
                                                              #16
                                                              Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                                              You think it simply needs a factory reset?

                                                                Comment

                                                                • tom66
                                                                  EVs Rule
                                                                  • Apr 2011
                                                                  • 32560
                                                                  • UK
                                                                  #17
                                                                  Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                                                  Sometimes, but I cannot be sure at all.

                                                                  We have seen plenty of Samsung TVs here with dead main boards. No idea what kills them.
                                                                  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

                                                                    • caphair
                                                                      Badcaps Legend
                                                                      • Nov 2011
                                                                      • 1249
                                                                      #18
                                                                      Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                                                      What's strange is when the 3.3v regulator was bad all the input voltages were steady. What usually causes voltage fluctuations?

                                                                        Comment

                                                                        • tom66
                                                                          EVs Rule
                                                                          • Apr 2011
                                                                          • 32560
                                                                          • UK
                                                                          #19
                                                                          Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                                                          Can be a bad startup cap. It's possible as the unit has warmed up, or cooled down, it's encountered other issues. Try heating the PSU with a hairdryer.
                                                                          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

                                                                            • caphair
                                                                              Badcaps Legend
                                                                              • Nov 2011
                                                                              • 1249
                                                                              #20
                                                                              Re: Samsung LN19B361C5D Backlight, No Picture/Sound

                                                                              Originally posted by tom66
                                                                              Can be a bad startup cap. It's possible as the unit has warmed up, or cooled down, it's encountered other issues. Try heating the PSU with a hairdryer.
                                                                              Tried, no change. There's a 10 ohm smd network resistor on mainboard that measures open but it leads to hdmi input, not sure if that was bad (as I tested on board) if it'd cause this problem?
                                                                              Last edited by caphair; 12-12-2012, 07:59 PM.

                                                                                Comment

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