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    #1

    Samsung T260

    Hi List Members,
    I am now the proud owner of a dead Samsung T260. It was made in May 2008, so I am hoping it doesn't have too many hours on it. It set me back $25.

    I took out the power supply circuit, and have attached some photos below. The caps look ok on appearance, but all the same I will change them just add to the reliability.

    At first glance, T301 looks like it became really hot; indeed, it does not have continuity across my ohm meter. Can anyone suggest a replacement?

    Also, I am thinking that something caused this to blow. There appears to be another hot spot just below the transformer, almost exactly where the 'Solder' arrow points.

    I read in another post on a T240 that I might suspect the transformer; I have attempted to take an ohm reading across the four different points, and I have annotated my photo. Can someone confirm that I did it correctly? If yes, does this confirm a dead transformer?

    Also, the hot spot in the direction of the 'Solder' arrow has a component below it, which I also suspect, for no other reason that it looks like it was hot once upon a time. Can anyone add their thoughts on this? I have added a closeup photo of that component as well.

    Thanks as always...

    LAS.
    Attached Files
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    #2
    Re: Samsung T260

    Originally posted by LAS View Post
    dead Samsung T260.
    Define dead.

    1) Does the power LED come on at all?

    2) Do you have any DC voltages at the connector on the power board? Measure and report the found DC voltage compared to what is written on the legend.
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      #3
      Re: Samsung T260

      Hi Retiredcaps,

      The power light comes on, but that is all that happens. No light at all from the screen, not even a quick flash of light.

      I will check the dc voltages later, hopefully tonight and report back.

      In my opening post, I stated that T301 looks like it was hot; actually, after looking at the board again, it looks like it was the resistor R301 that was hot. And it is open.

      Comment

        #4
        Re: Samsung T260

        Originally posted by LAS View Post
        it looks like it was the resistor R301 that was hot. And it is open.
        I would desolder R301 and verify it is completely open out of circuit.

        In addition, check picofuse F301 (the green one) just below R301. A good fuse should measure 1.0 ohms. You can measure the fuse "in circuit".

        It could be a simple fuse if you have no backlights.
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          #5
          Re: Samsung T260

          Also, what is the color band on R301? Your photo is nice and clear, but the colors are difficult for me to make out.
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            #6
            Re: Samsung T260

            OK, here we go:
            Pin 1 PWM DIM reads 0
            #2 should be 15v - reads 15.4
            #3 s/b gnd - reads 0
            #4 s/b gnd - reads 0
            #5 s/b gnd - reads 0
            #6 s/b 5.2v - reads 5.4
            #7 s/b 5.2 - reads 5.4
            #8 A-DIM - reads 0
            #9 on/off - reads 0
            #10 s/b 3.3v - reads 0 (!)
            #11 LED - reads 0
            #12 KEY1 - reads 0
            #13 KEY2 - reads 0
            #14 GND - reads 0

            Comment

              #7
              Re: Samsung T260

              Color band on R301 - I was about to consult the collective wisdom of the list because I couldn't make out the colors either.

              Comment

                #8
                Re: Samsung T260

                Originally posted by LAS View Post
                OK, here we go:
                #10 s/b 3.3v - reads 0 (!)
                What about the picofuse as per post #4?
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                  #9
                  Re: Samsung T260

                  Picofuse coming up next.

                  Meanwhile, R301 out of circuit now read 389k ohms.

                  Comment

                    #10
                    Re: Samsung T260

                    The green picofuse F301 just below R301 measures .2 ohms.

                    Comment

                      #11
                      Re: Samsung T260

                      1) Fuse is good.

                      2) Let's get a picture of the main logic board.

                      3) When you press the on/off button, I believe pin 9 should go from 0 to over 3V DC.

                      4) I'm looking at some other pics on the Internet for colors on R301.
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                        #12
                        Re: Samsung T260

                        Originally posted by LAS View Post
                        Meanwhile, R301 out of circuit now read 389k ohms.
                        One of the reasons we (mainly PlainBill and I) insist on clear focused pictures is for this very reason.

                        I was able to find another identical power board (IP-54155A) on badcaps.net that had a slightly better picture.

                        https://www.badcaps.net/forum/attach...1&d=1275552641

                        On the above pic, I can make out orange, white, yellow. According to

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

                        that is 39x10(4th power) or 390,000. So your reading 389k is correct.

                        The resistor is good despite the burned look.
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                          #13
                          Re: Samsung T260

                          Originally posted by LAS View Post
                          I read in another post on a T240 that I might suspect the transformer; I have attempted to take an ohm reading across the four different points, and I have annotated my photo. Can someone confirm that I did it correctly? If yes, does this confirm a dead transformer?
                          Okay, I didn't forget about this, but sometimes I don't work in the same order as everyone else.

                          According to

                          http://www.lcdparts.net/TransformerD...ProductID=3696

                          there are 4 secondary pins. The resistance should be 940 ohms between S1 and S2. Same for S3 and S4. If you are reading an open circuit, desolder the transformer and remeasure to verify.

                          If it is open, you have found the problem. There are plentiful replacement parts on ebay.com starting at $8 USD with free shipping.
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                            #14
                            Re: Samsung T260

                            Sorry you didn't like the first set of pictures. To my untrained eye they looked ok. I also couldn't read the resistor bands as I looked directly at it.

                            Here are a couple of shots of the logic board. I won't be able to test the on/off bit until the morning, but I will get back to you at that time.
                            Attached Files

                            Comment

                              #15
                              Re: Samsung T260

                              OK, I remove transformer in the morning and let's see what that brings...

                              Comment

                                #16
                                Re: Samsung T260

                                Originally posted by LAS View Post
                                Also, the hot spot in the direction of the 'Solder' arrow has a component below it, which I also suspect, for no other reason that it looks like it was hot once upon a time. Can anyone add their thoughts on this? I have added a closeup photo of that component as well.
                                Mosfets can get hot during operation and discolor the board. I have seen it many times and there is nothing to really worry about.

                                Datasheet is here



                                I would say if the inverter transfomer tests open out of circuit, you have probably found the culprit. If that is the problem, then you got a pretty sweet deal for $25 + $8 on a 26 inch monitor.
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                                  #17
                                  Re: Samsung T260

                                  Ha ha ha, it balances out that 2004 $30 one I bought a couple of weeks ago!

                                  I am still entertaining the idea of putting in new ccfl tubes and then donating it to our local school. They sure could use it.

                                  Comment

                                    #18
                                    Re: Samsung T260

                                    Originally posted by LAS View Post
                                    Sorry you didn't like the first set of pictures.
                                    Don't get me wrong, they are good (better than 98.5% of the people who post here), but the other picture was better since I could actually make out the colors without having to "make the question fit the answer".

                                    Anyway, we now know the actual value and so will future people.
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                                      #19
                                      Re: Samsung T260

                                      Originally posted by LAS View Post
                                      I am still entertaining the idea of putting in new ccfl tubes and then donating it to our local school. They sure could use it.
                                      If you put in new ccfls lamps, then be aware it is a very time consuming and fragile job. I did it once for a learning experience, but will probably not do it again. After I changed it out, I thought I had a nice 19 inch 2008 widescreen monitor. Then I turned it on and had a 1.5 inch vertical strip. ARRGGGHH. One of the tab bonds broke off and it is unrepairable.

                                      Step by step tutorial at

                                      http://www.ccflwarehouse.com/lasotu.html

                                      They are also sold "pre harnessed" to make the switch way easier, but obviously cost more.
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                                        #20
                                        Re: Samsung T260

                                        OK, you just talked me out of it! I'm better off using my time to find other project monitors with more potential.

                                        While I'm at it, I'm thinking of changing R301 to something a bit beefier. Perhaps 2W. A good idea?

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