Technika 22-880 startup issues

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  • notallbad
    Badcaps Legend
    • Oct 2012
    • 1190
    • UK

    #41
    Re: Technika 22-880 startup issues

    OK, PS b/d disconnected from main, no resistor just mains power
    PL703
    1 0v---------11 0v
    2 0v---------12 0v
    3 0v---------13 0v
    4 11.17v-------14 11.17v
    5 5v-----------15 5v
    6 5.3v--------16 0v
    7 0v ----------17 0v
    8 0v--------18 0v
    9 0v-----------19 0v
    10 0v-------------20 0v

    PL706
    1 22.1v
    2 22.1v
    3 0v
    4 0v
    5 0v
    6 0v

    Comment

    • notallbad
      Badcaps Legend
      • Oct 2012
      • 1190
      • UK

      #42
      Re: Technika 22-880 startup issues

      Main A/V: 17MB60-3.1

      S/C across D202 - Pin2 VIN on U23 (RTA8283A)

      Needs further investigation but trouble tracing layered pcb.

      Comment

      • notallbad
        Badcaps Legend
        • Oct 2012
        • 1190
        • UK

        #43
        Re: Technika 22-880 startup issues

        Erm, perhaps its not a diode afterall, but what is it? It reads S.C in-circuit so perhaps just a zero ohm jumper resistor??? But usually they have a '0' printed on them, but not this one.

        Its the 3rd SMD down on the immediate left (the black one)to U23 located near the top of the board.
        Attached Files

        Comment

        • notallbad
          Badcaps Legend
          • Oct 2012
          • 1190
          • UK

          #44
          Re: Technika 22-880 startup issues

          Just to be sure I haven't overlooked something I have gone back to the PS.

          With just power to the PS b/d I get the first reading and the second reading, in brackets, is with a 1k resistor between Pin 9 and Pin 17.
          PL703
          1 - 0v (0v)
          2 - 0v (0v)
          3 - 0v (0v)
          4 - 0v (0v)
          5 - 0v (0v)
          6 - 0v (0v)
          7 12vcc - 11.09v (8.5v-10v)
          8 12vcc - 11.09v (8.5v-10.2v)
          9 +5v_vcc - 4.97v (0.6v-2.2v)
          10 +5v_vcc - 4.97v (0.8v-2.2v)
          11 stby_5v - 5.23v (4.96v-5.03v)
          12 - 0v (0v)
          13 pwm_dim - 0v (0v)
          14 - 0v (0v)
          15 bkl_on/off - 0v (0v)
          16 - 0v (0v)
          17 stby_on/off - 0v (0.6v-2.2v)
          18 - 0v (0v)
          19 - 0v (0v)
          20 - 0v (0v)

          PL706
          1 24v - 21.9v (20.5v-21.5v)
          2 12v_con - 21.9v (20.5v-21.5v)
          3 bkl_on/off - 0v (0v)
          4 pwm_dim - 0v (0v)
          5 - 0v (0v)
          6 - 0v (0v)

          Without the resistor the voltages are steady readings but with the 1k resistor the voltages all fluctuate.

          Appreciate your help.

          Comment

          • notallbad
            Badcaps Legend
            • Oct 2012
            • 1190
            • UK

            #45
            Re: Technika 22-880 startup issues

            Would appear that I either mis-read the DMM when reading Pin 11 - stby_5v as it is actually only reading 0.5v, NOT 5.23v.

            Either something has now failed or I was reading it wrong everytime, which is possible but find it hard to believe as I have taken the reading so many times.

            Well anyway, what is likely to cause this?

            Comment

            • notallbad
              Badcaps Legend
              • Oct 2012
              • 1190
              • UK

              #46
              Re: Technika 22-880 startup issues

              Tracing back PL703 Pin 11 Stby_5v it goes back to a 3 leg, I think transistor, Q713, it has 1F printed on it. In the photo its located in the middle just below the 2 smd light brown caps.

              Top left leg - reads a dropping voltage to below 0.5v
              Top right leg - reads a steady 5.49v
              Bottom leg - reads a steady 11.07v

              Is this the transistor itself at fault as there is not anything else connected to this leg and the voltage is dropping at a rapid and steady rate. Internal leakage?
              Attached Files

              Comment

              • notallbad
                Badcaps Legend
                • Oct 2012
                • 1190
                • UK

                #47
                Re: Technika 22-880 startup issues

                Is it a SOT23 BC847B SMD NPN General Purpose Transistor?

                Comment

                • notallbad
                  Badcaps Legend
                  • Oct 2012
                  • 1190
                  • UK

                  #48
                  Re: Technika 22-880 startup issues

                  Testing in-circuit with a DMM in diode setting it gives different results to other '1F' trans on the board and not what would be expected.

                  So guess I'll have to source a replacement and go from there. The only concern I have is removing the existing and re-soldering the new without causing any damage to the board.
                  Last edited by notallbad; 11-04-2013, 07:29 PM.

                  Comment

                  • notallbad
                    Badcaps Legend
                    • Oct 2012
                    • 1190
                    • UK

                    #49
                    Re: Technika 22-880 startup issues

                    Might just try a BC547 or a BC547B as a temporary measure and replace later if and when I get it fully working.
                    Last edited by notallbad; 11-05-2013, 10:21 AM.

                    Comment

                    • notallbad
                      Badcaps Legend
                      • Oct 2012
                      • 1190
                      • UK

                      #50
                      Re: Technika 22-880 startup issues

                      Anyone know the difference between the BC547, BC547B, C etc...

                      Thanks

                      Comment

                      • tom66
                        EVs Rule
                        • Apr 2011
                        • 32560
                        • UK

                        #51
                        Re: Technika 22-880 startup issues

                        Different voltage ratings, usually, if not, then different gain parameters.
                        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

                        • notallbad
                          Badcaps Legend
                          • Oct 2012
                          • 1190
                          • UK

                          #52
                          Re: Technika 22-880 startup issues

                          By the looks of it I can remove the SMD transistor and use a T0-92 package transistor (on component side of the board) utilising the board holes that exist for a transistor Q714 that connects to all the same tracks.

                          Comment

                          • tom66
                            EVs Rule
                            • Apr 2011
                            • 32560
                            • UK

                            #53
                            Re: Technika 22-880 startup issues

                            That should be fine, I have done that before with Vestel which used SMD diode but had through hole pads, I just used the through hole pads as they were available.
                            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

                            • notallbad
                              Badcaps Legend
                              • Oct 2012
                              • 1190
                              • UK

                              #54
                              Re: Technika 22-880 startup issues

                              Cheers, and would a BC547 be fine?

                              Comment

                              • tom66
                                EVs Rule
                                • Apr 2011
                                • 32560
                                • UK

                                #55
                                Re: Technika 22-880 startup issues

                                A BC547B would work. A BC547 -might- work, but you'd need to take a chance unless you could analyse the circuit carefully to understand how it works.
                                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

                                • notallbad
                                  Badcaps Legend
                                  • Oct 2012
                                  • 1190
                                  • UK

                                  #56
                                  Re: Technika 22-880 startup issues

                                  Thanks, shall see if I have a 'B' first.

                                  Comment

                                  • notallbad
                                    Badcaps Legend
                                    • Oct 2012
                                    • 1190
                                    • UK

                                    #57
                                    Re: Technika 22-880 startup issues

                                    Using a BC547 TO-92 has brought the 5V_Stby back but still no go.

                                    Comment

                                    • notallbad
                                      Badcaps Legend
                                      • Oct 2012
                                      • 1190
                                      • UK

                                      #58
                                      Re: Technika 22-880 startup issues

                                      Found Q200 on main A/V, its either a FDC642 or a FDC604P, can't determine which one from the SM but its a PowerTrench MOSFET either way.

                                      Between Pins 3(Gate) and 4(Source) reads 32kOhms, on diode test no reading with probes both ways.
                                      However, Pins 4 to 1,2,5 and 6 (Drain) shows S.C, 0 ohms.
                                      And Pins 4,1,2,5,6 show S.C to CN706 Pins 12v_stby and 12v_vcc.
                                      The main a/v board is disconnected from the PS b/d and other boards.

                                      With boards connected and powered
                                      5.4v on Gate
                                      11v on Source and Drain


                                      On checking the Mosfet again there does not appear to be continuity between Pins 4 to 1,2,5 and 6.

                                      I would expect continuity when its powered, isn't that what it does? As the name 'Gate' suggests, allows Source voltage across to Drain. But would think it would be O.C, well have high resistance, when powered off.
                                      Last edited by notallbad; 11-08-2013, 05:57 AM.

                                      Comment

                                      • asas
                                        New Member
                                        • Oct 2013
                                        • 3
                                        • Portugal

                                        #59
                                        Re: Technika 22-880 startup issues

                                        Hello,
                                        notallbad, did you solve this fault?
                                        I have a similar fault on a 17PW05-3 PSU (Toshiba 22EL833G): hard to start and low voltage!
                                        12V is 11,27V
                                        24V is 22,99V
                                        (when the tv is on).

                                        Any tip will be very appreciated.
                                        Thanks.

                                        Comment

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