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    #1

    Broken Samsung 2493HM - blinking LED

    I have a Samsung 2493HM monitor that has gone bad. The LED light is blinking, but there is no picture on the screen.
    I had the same issue when the monitor was still under warranty,
    and I had the monitor fixed at a service center. They replaced / fixed the inverter board.

    I'm assuming its the same issue this time around.
    After reading a bit, I found out that the most common issues are bad capacitors.
    I opened the monitor to check the inverter board for bad caps, but couldn't find any caps that were visually damaged.
    (I've attached some pictures of the board.)


    I have no experience with soldering whatsoever, and I currently have no soldering equipment.
    I'm considering picking up a cheap soldering iron and a kit from ebay just to try.
    After watching some YouTube clips it seems managable.

    http://www.ebay.com/itm/Repair-Kit-S...-/330549799415

    Do you think the capacitor might be the problem, even though they are not visually damaged?
    Attached Files
    Tags: None
    #2
    Re: Broken Samsung 2493HM - blinking LED

    If you have got your solder iron already, unsolder the components with the glue on them and scrape off those remainding glues on the board. if you have a multimeter, measure the transistors qm802 and qm803 for short , out of the board. And also whether the resistor facing it is fused(open).

    Comment

      #3
      Re: Broken Samsung 2493HM - blinking LED

      Hi List Members,

      I am in the very same position as Froleo above. Over the Thanksgiving holidays, I acquired a Samsung 2493HM which also has a fast blinking LED power light, but no display whatsoever. I find myself at a somewhat disadvantage because I discovered that someone had already been playing around with the BN44-00195A power board in that there were several odd capacitors which had been substituted. They probably were looking for the quick fix of just changing out a couple of caps.

      Since then, I have changed all the caps to the recommended Panasonic FR, FM or FC series.

      In Newbie's post above, he writes about the fusible resistor facing the two transistors. The color code is red/red/silver/gold, which according to my interpretation is .22 ohms. My reading is .5 ohms. Could this be the culprit?

      And now on to QM802 and QM803. I removed them from the circuit - I found this was most easily done by removing them complete with the heat sink - and my readings were open across all combinations except for the center and right pins (when looking at it from the front side) which read 2.7m ohms.

      I can post photos of the power board if it would be beneficial, although at this time the transistors / heat sink has been removed.
      Last edited by LAS; 03-04-2013, 01:19 PM.

      Comment

        #4
        Re: Broken Samsung 2493HM - blinking LED

        Originally posted by LAS View Post
        The color code is red/red/silver/gold, which according to my interpretation is .22 ohms. My reading is .5 ohms. Could this be the culprit?
        1) Your test leads are likely 0.2 ohms. Add 0.22 to 0.2 and you might get around 0.5 depending on the round up algorithm on the Fluke 12B or 27.

        The Fluke 27/FM has a relative button which you can use to compensate for the resistance in the leads. That should put the resistor reading closer to 0.22 ohms.

        2) If you disconnect the main board, do you get steady 5V standby?

        3) With the main board disconnected, if you jumper 5V standby to PS_ON using a 1K ohm resistor, do the rest of the voltages come up (please report them)?

        4) Can you post a picture of the main board? Also post pictures of your power board.

        5) The readings for QM802 and QM803 suggest they are not shorted.
        Last edited by retiredcaps; 03-04-2013, 07:33 PM.
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        Comment

          #5
          Re: Broken Samsung 2493HM - blinking LED

          Thank you retiredcaps - these are some good suggestions. My next moment of opportunity will be this weekend. At that time, I'll put the transistors back onto the power board and will also post some photos after I check for 5V.

          Comment

            #6
            Re: Broken Samsung 2493HM - blinking LED

            Hi Retiredcaps,

            I did some more troubleshooting on my monitor this morning, and the results were not encouraging. I was unable to read any voltage readings on either the 5.3 side or the 24v side.

            The inverter and also the main board was not plugged in. Was I doing this correctly?

            I have attached photos of the power board, complete with the jumper resistor. I did not have a 1k available, so I used a 2.7k. Is that an acceptable alternative?

            I should also say that the sk763 7 pin ic has also been replaced; they were inexpensive from Hong Kong and I ordered some spares over the Christmas holidays. And I have spares if anyone needs one.

            There was also much glue on the board, and most of it has been removed.

            Both white fuses have been checked for continuity.

            CM851 and CM852 next to the 24v connector at top right were originally 1000uf 35v but due to a shortage have been temporarily replaced with 1000uf 25v. I'm thinking that's ok for the short term.

            All suggestions appreciated.
            Attached Files

            Comment

              #7
              Re: Broken Samsung 2493HM - blinking LED

              Without the main board and inverter connected, you should still at least see the 5.2 V standby voltage. What voltage are you seeing across the the large 82uf 450V capacitor? It should be approx. 170VDC.

              Comment

                #8
                Re: Broken Samsung 2493HM - blinking LED

                What is part number ICP801S? It is on the backside 8 pin IC.

                PS. Nice pics thanks to the California sunshine.
                Last edited by retiredcaps; 03-09-2013, 08:51 PM.
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                If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

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                Comment

                  #9
                  Re: Broken Samsung 2493HM - blinking LED

                  So you need to find out if you have the 5.2Vdc or not as suggested by jetadm123.
                  This diagram should match your board.
                  Attached Files
                  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

                    #10
                    Re: Broken Samsung 2493HM - blinking LED

                    I made more voltage measurements this morning, and found the following:

                    5.23v steady on standby with no jumper attached, no main board or inverter board attached;

                    162v on the 82uf big cap.

                    Retiredcaps, as to the IC801S, there is no part number. Maybe there was one there once upon a time. There is however a spot where it looks like it may have become hot.

                    As to the diagram, it is highly likely I missed something but I am not convinced it's the same as what I've got. For instance, my power board has two fuses coming off the AC connector, and I could only find one on the diagram.

                    Comment

                      #11
                      Re: Broken Samsung 2493HM - blinking LED

                      And now here is the front and back of the main board...
                      Attached Files

                      Comment

                        #12
                        Re: Broken Samsung 2493HM - blinking LED

                        Good. You've verified that the 5V standby circuit is working. Now, you have to verify the PFC circuit is working. Connect the mainboard to the power supply. Press the on/off button and the voltage across the 82uf 450V cap should rise to approx. 390VDC.

                        Comment

                          #13
                          Re: Broken Samsung 2493HM - blinking LED

                          With main board and inverter board connected, the big 82uf cap is still reading 162vdc.

                          Comment

                            #14
                            Re: Broken Samsung 2493HM - blinking LED

                            You will need to verify that the 3-5V signal from the mainboard is present to turn on the the power supply. Look for this voltage at the PS_ON point, while pressing the on/off button. I'm going to have to step away for a while.

                            Comment

                              #15
                              Re: Broken Samsung 2493HM - blinking LED

                              Jetadm123, can i use the on/off switch on the power supply instead?

                              Comment

                                #16
                                Re: Broken Samsung 2493HM - blinking LED

                                No worries about stepping away. I stepped away from this project for three months.

                                With main board connected, PS_ON fluctuates between 0 and 1 (hard to tell exactly with my digital meter), standby still steady at 5.23v, and the big cap is still 162vdc.

                                Comment

                                  #17
                                  Re: Broken Samsung 2493HM - blinking LED

                                  And the above was done using the power button on the edge of the monitor. On/off power switch next to the power plug was set to 'on'.

                                  Comment

                                    #18
                                    Re: Broken Samsung 2493HM - blinking LED

                                    You may have multiple problems.

                                    1) Jumping 5V standby to PS_ON with main board disconnected should have brought up the other power supply rails. There may be a problem with the PFC section?

                                    2) Getting a reading of between 0 and 1V DC on the PS_ON pin with the main board connected suggests there is something could be wrong with the main board. The main board, if working correctly, should be sending out > 3V DC (typically).

                                    3) IC113 on the main board looks like a fixed 2.5V regulator. Measure the 3 pins (including the cut pin) with respect to ground. Report your readings.

                                    4) Measuring the big cap and PFC section can involve DCV in the 400V range. BE CAREFUL.
                                    Last edited by retiredcaps; 03-10-2013, 05:02 PM.
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                                    If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                                    We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                                    Please do not post inline and offsite as they slow down the loading of pages.

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                                    Comment

                                      #19
                                      Re: Broken Samsung 2493HM - blinking LED

                                      Also, try checking fuse F601 at the top of your mainboard.

                                      Comment

                                        #20
                                        Re: Broken Samsung 2493HM - blinking LED

                                        F601 tested ok
                                        IC113: 3.4v, 0v on the short leg, 2.5v.

                                        I put the jumper back on to test just once more, with similar results. 5v on standby, 3v on pson, and 0v up on the 24v pin.

                                        I'd believe multiple problems on this monitor. I wasn't the first to crack it open, and who knows what went on before it came to me.

                                        In the meantime, thanks all for the suggestions.

                                        Comment

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