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    Samsung Syncmaster 245B

    Hi all, never replaced a capaciter in my life so hoping for some help on where to start. My syncmaster's power light comes on and flashes when powered and turns to solid blue when connected to a PC, but there's no life in the screen at all (tried shining a light on it, it's completely black).

    I've dismantled it and can see no externally damaged caps so just wondering where to start really. What tools do I need to remove the caps other than a soldering iron? Do they need discharging in anyway?

    Cheers,

    Rhodri.

    #2
    Re: Samsung Syncmaster 245B

    1. Post clear pictues of each board using "Manage Attatchments" on the post page.
    2. Take notes on what part number of cap you remove and what values it has. example: c123 = 1000uF 16V
    3. Pay attention to polarity - the exact direction it's mounted to the board. The strip is negative.
    4. Order replacement caps from Badcaps.net.

    Thats a start. The problem may not be the caps but if you're not used to testing caps, this is one way to rule them out.
    The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

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      #3
      Re: Samsung Syncmaster 245B

      Thanks, I'll make a start on that tonight. Do I need to discharge all of the capacitors before I start working on them? (I'm popping down to maplin tonight anyway so was just going to get a large resistor and some wire to discharge the big cap on the power board).

      Comment


        #4
        Re: Samsung Syncmaster 245B

        You only need to discharge the big one.
        Originally posted by PeteS in CA
        Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
        A working TV? How boring!

        Comment


          #5
          Re: Samsung Syncmaster 245B

          Ok here are a few photos, wasn't really sure what was important so if you need anything else I'll grab a photo of it.

          Cheers!
          Attached Files

          Comment


            #6
            Re: Samsung Syncmaster 245B

            And a few more.
            Attached Files

            Comment


              #7
              Re: Samsung Syncmaster 245B

              That looks like a fairly solid board so it could prove difficult to fix. You have a couple connectors on that power supply. The white ones on the edge of the board. In the pictures they are obscured by the caps, could you please list everything that's written above the connectors? That way we can give you hints on what you can check.

              Also have a digital multimeter handy. That comes without asking usually but there are some folks that don't actually have one at the moment they post here.
              Originally posted by PeteS in CA
              Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
              A working TV? How boring!

              Comment


                #8
                Re: Samsung Syncmaster 245B

                1) See attached pic.

                2) The yellow component is a voltage regulator. The part number might be something like AS1117-18. The suffix, 18, indicates the DC output voltage.

                With power on and lcd plugged in, set your multimeter to 20V DC (if manual ranging). Use a ground screw on the logic board for your black probe. Your red probe will go on each pin (one at a time) on the voltage regulator. Report the findings.

                3) The red component is a DC/DC converter. The datasheet is at



                Refer to page 2 and see the diagram labeled TO263-5L.

                Again with your multimeter set on 20V DC and your black probe on a ground screw, put your red probe on all pins (one at a time) and report voltages.
                Attached Files
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                  #9
                  Re: Samsung Syncmaster 245B

                  I'll need to pick up a multimeter (terrible I don't have one to be honest), would I need to reasemble the bulk of the monitor before attempting to measure the voltages? Anything I'd need to be careful of? Because I think the ground screw goes through the metal chassis, but it'll be impossible to get to the chip when it's attached to that.

                  Attached a diagram of the connections on the power supply board.
                  Attached Files

                  Comment


                    #10
                    Re: Samsung Syncmaster 245B

                    A basic 830B multimeter should suffice for now. Look for a UNI-T branded one, those are decent compared to the nonames.

                    Yes you will have to wire everything together but that doesn't mean they have to go in the same places. Put some plastic or cardboard over the back of the LCD panel and put the power supply and logic board on top of that. That way you can measure stuff without assembling the whole thing. For more complicated measurements you solder a wire to the spot then power the monitor... but at least the main connectors should be accessible without the need for such stunts. You don't have to wire the ground lead of the plug now.

                    Black lead of multimeter always goes to the nearest GND. Red lead goes to the circuit you are testing. First things to check are the voltage rails which are SB, 5.4v and 24v. SB is usually 5 volts.
                    Originally posted by PeteS in CA
                    Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                    A working TV? How boring!

                    Comment


                      #11
                      Re: Samsung Syncmaster 245B

                      Originally posted by Rhodri2311 View Post
                      I'll need to pick up a multimeter (terrible I don't have one to be honest), would I need to reasemble the bulk of the monitor before attempting to measure the voltages?
                      If you don't plan on doing many electronics repair, borrow a multimeter from a friend.

                      You have to all the boards connected. You don't need to put the case on at all.

                      The voltages on the logic card are generally less than 5V DC.
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                      Please do not post inline and offsite as they slow down the loading of pages.

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                        #12
                        Re: Samsung Syncmaster 245B

                        A 830B is under $10 and is good for having around the house even if you only use it once a year.
                        Originally posted by PeteS in CA
                        Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                        A working TV? How boring!

                        Comment


                          #13
                          Re: Samsung Syncmaster 245B

                          I frequently switch parts out of several PC's and ment to pick one up few times to make fault finding easier so about time I picked one up!

                          Would this be sufficient? http://www.maplin.co.uk/ut30b-palm-s...ltimeter-46498

                          Thanks for all the help.

                          Comment


                            #14
                            Re: Samsung Syncmaster 245B

                            Originally posted by Rhodri2311 View Post
                            I'll need to pick up a multimeter (terrible I don't have one to be honest), would I need to reasemble the bulk of the monitor before attempting to measure the voltages? Anything I'd need to be careful of? Because I think the ground screw goes through the metal chassis, but it'll be impossible to get to the chip when it's attached to that.

                            Attached a diagram of the connections on the power supply board.

                            If you're going to measure voltages off the logic card, then you should reassemble the boards, since the logic card gets it's power from the power board. Also, with power off and meter set to resistance, check the fuse (circled in photo) on the logic card.
                            Attached Files

                            Comment


                              #15
                              Re: Samsung Syncmaster 245B

                              Probably won't get a chance to look at it tomorrow, but should be able to have a fiddle with it wednesday night hopefully, I'll grab as many testings as I can then. Is the ground screw on the logic board just the metal surround on the four screw holes or will I need to earth it to something?

                              Comment


                                #16
                                Re: Samsung Syncmaster 245B

                                That meter will do fine. And yes "ground" is just the metal surround on the screw holes.
                                Originally posted by PeteS in CA
                                Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                                A working TV? How boring!

                                Comment


                                  #17
                                  Re: Samsung Syncmaster 245B

                                  Ok some results! First of all I tried testing the logic board fuse, but couldn't get a stable reading at all. It seemed to constantly fluxtuate from 0 to anywhere up to 100.

                                  Next the volatage regulator on the logic board. With the pins at the top and left to right the results were: 1.8v, 0, 2.9v

                                  The DC converter: (pins at top left to right again): 0, 3.3v, 0, 3.33v, 5.2v

                                  And the power supply board:
                                  +24 = 0.03v
                                  SB = 5.23v
                                  5.4v = 0

                                  I'm guessing that's not a sign of a healthy board =/

                                  Comment


                                    #18
                                    Re: Samsung Syncmaster 245B

                                    Let's make sure your multimeter is working right first.

                                    1) Put your multimeter on 200 ohms (if manual). Touch the 2 probes together. What is the reading?

                                    2) For the fuse, you should be measuring ohms with power off and lcd unplugged. A good fuse should read under 1.0 ohms.
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                                      #19
                                      Re: Samsung Syncmaster 245B

                                      Originally posted by Rhodri2311 View Post
                                      With the pins at the top and left to right the results were: 1.8v, 0, 2.9v
                                      What is the part number of the voltage regulator?
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                                      Please do not post inline and offsite as they slow down the loading of pages.

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                                        #20
                                        Re: Samsung Syncmaster 245B

                                        Balls read the instructions and had my red and black wires plugged in the wrong way round. Touching the wires gives a result of 0.03 once it's settled down.

                                        Resistence across the fuse seems to be 0.06.

                                        The voltage regulator is: J162 953-18
                                        Last edited by Rhodri2311; 02-03-2011, 01:13 PM.

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