Technosonic 1908

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  • sienoki
    sienoki
    • Jan 2012
    • 314

    #1

    Technosonic 1908

    Another project im hoping to fix..
    This lcd tv i got from a friend to try and fix..no power lights no nothing dead.. has a ticking noise from transformer..after googling the psu (MSDV1901-ZC01(B) there was a common fault with the 2 schotty diodes on the heatsink..so i replaced them with MBR20100CT-20a-100v..still same issue and ticking noise remains
  • Scenic
    o.O
    • Sep 2007
    • 2640
    • Germany

    #2
    Re: Technosonic 1908

    check for shorts on the output(s) and replace the startup cap (usually 47uF 35-50V).
    That's usually the first thing I try for ticking powersupplies.
    If that's not it, look up the datasheet on the SMPS controller IC and start checking that one.

    Comment

    • sienoki
      sienoki
      • Jan 2012
      • 314

      #3
      Re: Technosonic 1908

      Originally posted by Scenic
      check for shorts on the output(s) and replace the startup cap (usually 47uF 35-50V).
      That's usually the first thing I try for ticking powersupplies.
      If that's not it, look up the datasheet on the SMPS controller IC and start checking that one.
      Is the start up cap usually in the psu area if so mine was 50v 22uf i replaced that 1 but no joy..where would i start testing now..thx
      Attached Files

      Comment

      • sienoki
        sienoki
        • Jan 2012
        • 314

        #4
        Re: Technosonic 1908

        where will that IC controller be..thx

        Comment

        • bbjunkie
          Badcaps Veteran
          • Dec 2011
          • 301

          #5
          Re: Technosonic 1908

          Originally posted by sienoki
          Is the start up cap usually in the psu area
          See attached photo.

          Controller is usually on the underside. Small surface mount IC

          Post a pic of the underside, and the number on any chips close to the startup cap on the opposite side of the board.

          I'm not the best person to be giving advice, I've got a PSU ticking at present and cant locate the source of the problem!
          Attached Files

          Comment

          • PlainBill
            Badcaps Legend
            • Feb 2009
            • 7034
            • USA

            #6
            Re: Technosonic 1908

            You're going to have to give us a little more to work with. I really prefer that the picture cover the entire board.. including the edges.

            The controller could be the device fastened to the heat sink, it could be on the bottom of the board, or it could be on the top of the board, but in the shadows. It will be in the neighborhood of the very large cap.

            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

            • sienoki
              sienoki
              • Jan 2012
              • 314

              #7
              Re: Technosonic 1908

              Originally posted by sienoki
              where will that IC controller be..thx
              The 3 blue disc caps are c103..103m-1kv..c102..101k-1kv..c114..472z-y1 250v
              how do i measure those..thx

              r101 & r102 both 105 resistors measure.948m
              r104..104 resistor..94.5k
              r121..104 resistor..94.5k
              r110..470 resistor..47.0
              c109 & c106 yellow box caps.22k275v..MCY/HT BOTH MEASURE 1.816m
              thx guys sorry for the poor pics im having to use my phone at moment..the circled cap was the 1 i replaced..theres no smds on underside of board..the ic attached to the heatsink has 6 legs & will need to desolder as i cant see any numbers on it clearly
              Attached Files
              Last edited by sienoki; 02-15-2012, 06:43 PM.

              Comment

              • sienoki
                sienoki
                • Jan 2012
                • 314

                #8
                Re: Technosonic 1908

                Originally posted by sienoki
                The 3 blue disc caps are c103..103m-1kv..c102..101k-1kv..c114..472z-y1 250v
                how do i measure those..thx

                r101 & r102 both 105 resistors measure.948m
                r104..104 resistor..94.5k
                r121..104 resistor..94.5k
                r110..470 resistor..47.0
                c109 & c106 yellow box caps.22k275v..MCY/HT BOTH MEASURE 1.816m
                thx guys sorry for the poor pics im having to use my phone at moment..the circled cap was the 1 i replaced..theres no smds on underside of board..the ic attached to the heatsink has 6 legs & will need to desolder as i cant see any numbers on it clearly
                I removed the big cap to get a good view of ic..it reads F1G45-CW0765R
                also when i first changed the schotty diodes i kind of overheated the pads abit..so i added a trace..
                Attached Files
                Last edited by sienoki; 02-15-2012, 07:15 PM.

                Comment

                • sienoki
                  sienoki
                  • Jan 2012
                  • 314

                  #9
                  Re: Technosonic 1908

                  Originally posted by sienoki
                  I removed the big cap to get a good view of ic..it reads F1G45-CW0765R
                  also when i first changed the schotty diodes i kind of overheated the pads abit..so i added a trace..
                  Whats this 4 legged item between yellow cupoid cap & large cap..
                  Ive to far only changed the start up cap would replacing all the caps give me any standby by light or power to backlights etc..or is my issue situated only within the psu area of the board..thx

                  The transformer or within that area has stopped ticking now but still dead..if i desoldered the transformer how can i test it to make sure its not dead..thx
                  Attached Files
                  Last edited by sienoki; 02-16-2012, 08:07 AM.

                  Comment

                  • tom66
                    EVs Rule
                    • Apr 2011
                    • 32560
                    • UK

                    #10
                    Re: Technosonic 1908

                    That's a bridge rectifier.

                    -

                    What do the output voltages measure at?
                    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

                    • sienoki
                      sienoki
                      • Jan 2012
                      • 314

                      #11
                      Re: Technosonic 1908

                      Originally posted by tom66
                      That's a bridge rectifier.

                      -

                      What do the output voltages measure at?
                      Am i testing the bridge rectifier with power on & on 20v setting on my multimeter..thx

                      Comment

                      • tom66
                        EVs Rule
                        • Apr 2011
                        • 32560
                        • UK

                        #12
                        Re: Technosonic 1908

                        Originally posted by sienoki
                        Am i testing the bridge rectifier with power on & on 20v setting on my multimeter..thx
                        Use diode test.

                        BUT...

                        If the bridge rectifier is dead the fuse will blow or the power supply will not work at all.

                        It is probably not the cause of your problem.
                        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

                        • selldoor
                          Slow Learner
                          • Dec 2010
                          • 7870

                          #13
                          Re: Technosonic 1908

                          I am butting in here just on the side of safety.
                          I believe that the Bridge Rectifier is in the HOT part of the board
                          and it turns the 250v AC into around 370v DC so if you set your meter on 20v there will be smoke.
                          I am not sure which pins are AC and which are DC - it might say on the board? or you could get a data sheet for the part number.

                          I think you can test it power OFF as well but not as a voltage but as a diode Take a multi-Meter and switch it to Ohm x 1
                          Test between one of the "~" and "+" legs.
                          You should get either an almost-zero reading in one direction, and when you reverse the test probes, you should get an almost infinite reading.
                          Now try the same between this "~" leg and "-".
                          Same as above.
                          Now repeat the same tests with the other "~" leg, and "+", and then "-".
                          Same as above.
                          If you either get almost zero or almost infinite in BOTH directions, then the rectifier burnt out.

                          Reading previous bits it is unusual for the blue ceramic caps to fail and same goes for the box caps and even the BIG 400v or 450v cap
                          Please upload pictures using attachment function when ask for help on the repair
                          http://www.badcaps.net/forum/showthread.php?t=39740

                          Comment

                          • sienoki
                            sienoki
                            • Jan 2012
                            • 314

                            #14
                            Re: Technosonic 1908

                            Originally posted by selldoor
                            I am butting in here just on the side of safety.
                            I believe that the Bridge Rectifier is in the HOT part of the board
                            and it turns the 250v AC into around 370v DC so if you set your meter on 20v there will be smoke.
                            I am not sure which pins are AC and which are DC - it might say on the board? or you could get a data sheet for the part number.

                            I think you can test it power OFF as well but not as a voltage but as a diode Take a multi-Meter and switch it to Ohm x 1
                            Test between one of the "~" and "+" legs.
                            You should get either an almost-zero reading in one direction, and when you reverse the test probes, you should get an almost infinite reading.
                            Now try the same between this "~" leg and "-".
                            Same as above.
                            Now repeat the same tests with the other "~" leg, and "+", and then "-".
                            Same as above.
                            If you either get almost zero or almost infinite in BOTH directions, then the rectifier burnt out.

                            Reading previous bits it is unusual for the blue ceramic caps to fail and same goes for the box caps and even the BIG 400v or 450v cap
                            When testing the legs of the rectifier from bottom side with power on it keep on tripping my fuse box..so im gonna leave this 1 as i dont want to blow myself up..thx

                            With the fluke 77 series II multimeter

                            I know my limits so thx guys for your help in troubleshooting this set but im gonna give him it back
                            Last edited by sienoki; 02-16-2012, 11:06 AM.

                            Comment

                            • selldoor
                              Slow Learner
                              • Dec 2010
                              • 7870

                              #15
                              Re: Technosonic 1908

                              Good Idea!! (not blowing yourself up- not the edit) as Tom says probably not the problem


                              Originally posted by sienoki
                              I removed the big cap to get a good view of ic..it reads F1G45-CW0765R
                              Almost missed this - I have attached what I think is the data sheet for it.
                              (or its equivalent)
                              I dont know enough to suggest how to test it but Plainbill or the others
                              will.
                              Attached Files
                              Please upload pictures using attachment function when ask for help on the repair
                              http://www.badcaps.net/forum/showthread.php?t=39740

                              Comment

                              • sienoki
                                sienoki
                                • Jan 2012
                                • 314

                                #16
                                Re: Technosonic 1908

                                Originally posted by selldoor
                                I am butting in here just on the side of safety.
                                I believe that the Bridge Rectifier is in the HOT part of the board
                                and it turns the 250v AC into around 370v DC so if you set your meter on 20v there will be smoke.
                                I am not sure which pins are AC and which are DC - it might say on the board? or you could get a data sheet for the part number.

                                I think you can test it power OFF as well but not as a voltage but as a diode Take a multi-Meter and switch it to Ohm x 1
                                Test between one of the "~" and "+" legs.
                                You should get either an almost-zero reading in one direction, and when you reverse the test probes, you should get an almost infinite reading.
                                Now try the same between this "~" leg and "-".
                                Same as above.
                                Now repeat the same tests with the other "~" leg, and "+", and then "-".
                                Same as above.
                                If you either get almost zero or almost infinite in BOTH directions, then the rectifier burnt out.

                                Reading previous bits it is unusual for the blue ceramic caps to fail and same goes for the box caps and even the BIG 400v or 450v cap
                                When measuring this rectifier in dioide mode with above sequence i get .512 then .OL the reverse is .512 an almost zero?..thx

                                Comment

                                • selldoor
                                  Slow Learner
                                  • Dec 2010
                                  • 7870

                                  #17
                                  Re: Technosonic 1908

                                  That's half the test -looks good to me- picture worth a thousand words:
                                  http://www.youtube.com/watch?v=dqkT6hF0O3E

                                  Just found this
                                  Please upload pictures using attachment function when ask for help on the repair
                                  http://www.badcaps.net/forum/showthread.php?t=39740

                                  Comment

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