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    #1

    Samsung LN26B360

    Hi folks,

    Newbie here, first post. Took radio/tv servicing 35 years ago but did not follow through with it till now as I am just retired. Help a bit in a sale/service shop of my friends a bit but not since plasmas, lcd etc came on line. Hope to spend more time as a hobby trying to get some tossed televisions back to life.
    Found this great sight and hope not to sound too ignorant with some questions as it will take a lot of time to get up to speed for me in the technology end.

    This lcd television shown built in April 2009 has no picture but sound and I pulled the ps/inverter board (BN4400259A) and found 2 of the 3 power diodes open. I was wondering if these could have fail because of other problems farther up the ladder. The fuses check out okay.

    I will attempt to post a picture hope it will come out okay because I have never attempted to do that before.

    regards
    Brent
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    #2
    Re: Samsung LN26B360

    Originally posted by coffee grinder View Post
    Hi folks,

    Newbie here, first post. Took radio/tv servicing 35 years ago but did not follow through with it till now as I am just retired. Help a bit in a sale/service shop of my friends a bit but not since plasmas, lcd etc came on line. Hope to spend more time as a hobby trying to get some tossed televisions back to life.
    Found this great sight and hope not to sound too ignorant with some questions as it will take a lot of time to get up to speed for me in the technology end.

    This lcd television shown built in April 2009 has no picture but sound and I pulled the ps/inverter board (BN4400259A) and found 2 of the 3 power diodes open. I was wondering if these could have fail because of other problems farther up the ladder. The fuses check out okay.

    I will attempt to post a picture hope it will come out okay because I have never attempted to do that before.

    regards
    Brent
    A couple of points in no particular order.

    A 'sight' is finding Sophia Loren (or Anne Hathaway, depending on your age) skinny-dipping. This is a 'site', and depending on your needs, can be even more delightful than Ms Loren or even Ms Hathaway.

    I'd give you a C+ on the picture. Two simple things will elevate your next picture to an 'A'.

    1. Turn off the flash and take the picture by natural light. Next to a window on a sunny day is best.
    2. Show the full board, even the meaningless bits at the ends.

    Now on to the more important stuff. You have an unusual set of symptoms. I suspect those diodes are in the PFC circuit. Certainly the main bridge rectifier is visible above and slightly right. A picture of the back side of the board would be a big help.

    The service manual is available here.

    PlainBill
    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

    Comment

      #3
      Re: Samsung LN26B360

      The diodes in question kinda confuses me. I'm not too much into the engineering side of things with understaning circuits but I was wondering since the symptoms were "sound but no picture" then why would the sound work if the main power diodes are open? Or are they simply in the video circuit and have nothing to do with audio?
      The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

      Comment

        #4
        Re: Samsung LN26B360

        Originally posted by Dgtech View Post
        The diodes in question kinda confuses me. I'm not too much into the engineering side of things with understaning circuits but I was wondering since the symptoms were "sound but no picture" then why would the sound work if the main power diodes are open? Or are they simply in the video circuit and have nothing to do with audio?
        That had me wondering too. The answer is 'incorrect assumption'. If you look at the heatsink towards the upper right corner of the picture you will see the main rectifier. Subject to review when I see a picture of the bottom side of the board, I believe the silver 'box' just below these diodes is an inductor or transformer for the PFC circuit, and these diodes are part of that circuit.

        PlainBill
        For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

        Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

        Comment

          #5
          Re: Samsung LN26B360

          There were bad batch of fat axial diodes in those model. Just right of center is the three diodes, one of them is bad (leaky). This is right under the fat capacitor on it's side. Replace this diode with proper specs.

          This prevents TV backlight from turning on.

          Cheers, Wizard

          Comment

            #6
            Re: Samsung LN26B360

            Thank you for the replies and info. Also a special thanks to PlainBill for the C+ on my photography and the hints for a better picture.

            Brent

            Comment

              #7
              Re: Samsung LN26B360

              Diodes are supposed to be read open and some resistance other way. But this diode that reads low both ways is the one you have to replace.

              Is that unsoldered diode that reads both ways as leaky? Very often they read dead shorted. But leaky semiconductors do happen, which you have.

              Check again. Keep in mind if your multimeter have diode check, use that and ohm check too.

              Cheers, Wizard

              Comment

                #8
                Re: Samsung LN26B360

                Wizard the 2 tested okay with the diode tester on my meter and the other showed about 25 ohms either way. Not sure why I had come up with the wrong conclusion in my first post as I should have known better. Appreciate your comments.

                Brent

                Comment

                  #9
                  Re: Samsung LN26B360

                  Now you found the problem! Fit a diode of similar or better specs.

                  25 ohms is leaky. Shorted silicon devices looks like piece of wire, under 1 ohm.

                  Cheers, Wizard

                  Comment

                    #10
                    Re: Samsung LN26B360

                    Perhaps it's obvious, but if the three diodes have the same part number, they should all be replaced.

                    PlainBill
                    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                    Comment

                      #11
                      Re: Samsung LN26B360

                      PlainBill,

                      Not this one. This is just only one diode that were from bad batch and this is covered in samsung's bulletin for this.

                      Cheers, Wizard

                      Comment

                        #12
                        Re: Samsung LN26B360

                        Where can I find the specific bulletin for this? Also, anyone know which specific diode is bad? and also, what are the specs of those diodes?

                        Comment

                          #13
                          Re: Samsung LN26B360

                          I had Samsung LN32B360 same power & inveter board like Samsung LN26B360 find one (Fast Recovery Rectifiers) is short parts write on diodes is MUR340AX SSG 09111
                          where I can buy this diodes
                          Thanks

                          Comment

                            #14
                            Re: Samsung LN26B360

                            Originally posted by hoadle View Post
                            I had Samsung LN32B360 same power & inveter board like Samsung LN26B360 find one (Fast Recovery Rectifiers) is short parts write on diodes is MUR340AX SSG 09111
                            where I can buy this diodes
                            Thanks
                            It's a 'jelly bean' part. Google MUR340AX. The first link takes you to the manufacturer's spec sheet. Order parts from your favorite supplier that meet or exceed the specs.

                            This has been pointed out repeatedly. If you include your location in your profile, we may be able to suggest suppliers. Without that information, I'm not going to take the time to figure out which (if any) of the 10,000 fast recovery diodes Mouser has on hand is suitable.

                            PlainBill
                            For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                            Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                            Comment

                              #15
                              Re: Samsung LN26B360

                              Sorry PlainBill
                              I try Google MUR360AX (my bad miss typing MUR360AX to MUR340AX & I just come back home after long work night) find http://www.leposelec.com/product_list.asp?id=70&i=
                              I just wake up & find MUR360AX = DO-201AD at same website above.
                              But I know you good man hepl some one out there to T/S & find the right parts & supply
                              I just do the T/S & repair electronic for my hobby (every time if I didn't know, I will ask or Google)
                              Thanks

                              Comment

                                #16
                                Re: Samsung LN26B360

                                Originally posted by hoadle View Post
                                Sorry PlainBill
                                I try Google MUR360AX (my bad miss typing MUR360AX to MUR340AX & I just come back home after long work night) find http://www.leposelec.com/product_list.asp?id=70&i=
                                I just wake up & find MUR360AX = DO-201AD at same website above.
                                But I know you good man hepl some one out there to T/S & find the right parts & supply
                                I just do the T/S & repair electronic for my hobby (every time if I didn't know, I will ask or Google)
                                Thanks
                                For the last time, I don't know what country you are in. Telling you that they are available from Jan Freeberg in Denmark won't do you any good if you live in Barbados. Why should I waste 10 minutes identifying a part number that may useless to you if you won't take a minute to update your profile? Click User CP, click Edit your Details then scroll down to Location.

                                I will ignore all future posts from you until you update your profile to indicate the country you live in.

                                PlainBill
                                For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                                Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                                Comment

                                  #17
                                  Re: Samsung LN26B360

                                  Ok I already update profile
                                  I live at Lincoln, Nebraska US 68526
                                  About 21 hours 26 mins drive to you place (Phoenix, AZ)
                                  Thanks

                                  Comment

                                    #18
                                    Re: Samsung LN26B360

                                    Originally posted by hoadle View Post
                                    Ok I already update profile
                                    I live at Lincoln, Nebraska US 68526
                                    About 21 hours 26 mins drive to you place (Phoenix, AZ)
                                    Thanks
                                    OK, that makes it easy. OK, not so easy. An exact match is Diodes, Inc SF30JG-T. Non-stock at both DigiKey and Mouser. Darn.

                                    OK, it looks like 497-4415-1-ND is a good substitute. And at $0.83 each they aren't going to break the bank.

                                    Don't come to Phoenix. There are a bunch of crazy people here. The Sheriff doesn't actually run the department. His assistant does; the assistant makes $170,000 a year and lost his home to foreclosure. When they checked the assistant's work computer they discovered he spent most of his time on eBay.

                                    PlainBill
                                    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                                    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                                    Comment

                                      #19
                                      Re: Samsung LN26B360

                                      Thanks

                                      Comment

                                        #20
                                        Re: Samsung LN26B360

                                        My parts come in replace Diodes & backlight turn on couple second & shut off check the new Diodes is short again will T/S late

                                        Comment

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