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Koban - Current Clamp Meter - DMM

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    Koban - Current Clamp Meter - DMM

    The factory / reseller ... don't know anything about the device (Schematic, Service manual, etc) and I need to repair this DMM - Clamp Meter.

    2TY - Transistor - Q5 (Diode mode ok)

    CHX ??? 5 Pins - U3

    C31 ??? Burn,

    Tested - V, Ohm, Diode, ºC ... don't see any errors

    Thanks in advance for all info
    Ruy
    Attached Files

    #2
    Re: Koban - Current Clamp Meter - DMM

    CHX may be XC6116H028MR

    Comment


      #3
      Re: Koban - Current Clamp Meter - DMM

      Originally posted by stj View Post
      CHX may be XC6116H028MR
      Thank you,

      CHX ... one more letter or number in Koban_1.JPG
      I can't find PDF with that reference.

      Thank
      Ruy

      Comment


        #4
        Re: Koban - Current Clamp Meter - DMM

        Originally posted by stj View Post
        CHX may be XC6116H028MR
        @neuron
        stj is most likely right! A simple quick search returns:
        Part No.: XC6116H028MR, SmdCode: CHX, Manufacturer: Torex, Package: SOT-25, Pin: 5, Memo: XC6116H028MR, Description: 2.8V Voltage detector, 0.1%, Delay time = 1.6s
        The datasheet may not be easy to find but that`s not your major concern, right?
        Either way, you can find here the datasheet.
        Last edited by megaraider; 12-20-2020, 03:12 PM.

        Comment


          #5
          Re: Koban - Current Clamp Meter - DMM

          Originally posted by megaraider View Post
          @neuron
          stj is most likely right! A simple quick search returns:
          Part No.: XC6116H028MR, SmdCode: CHX, Manufacturer: Torex, Package: SOT-25, Pin: 5, Memo: XC6116H028MR, Description: 2.8V Voltage detector, 0.1%, Delay time = 1.6s
          The datasheet may not be easy to find but that`s not your major concern, right?
          Either way, you can find here the datasheet.
          Boa tarde megaraider,

          And the procedure to test ?

          The last letter ... is necessary?

          C31 no info?

          I can follow the tracks in the board and
          tested 2TY and all resistors around the C31.

          C31 in the board ...?

          Thank you
          Ruy

          Comment


            #6
            Re: Koban - Current Clamp Meter - DMM

            mabe you can find a schematic for a similar meter with the same chip.
            Semico CS7721CN
            i also found this:
            "The CS7721CN is pin for pin compatible with Fortune Semiconductor FS9721"

            and a LOT of meter info is here:
            https://sigrok.org/
            Attached Files
            Last edited by stj; 12-22-2020, 02:41 PM.

            Comment


              #7
              Re: Koban - Current Clamp Meter - DMM

              A long list of chips, schematics, teardown, ... info on Multimeters (DMM):
              http://improwis.com/projects/reveng_multimeters/

              You can find a long list of devices using the CS7721CN chip along with detailed info.

              A very quick look pop-up UT61E (schematics) and Wintex TD2200, quite similar to UT61E. The later as "IC11: some tiny SOT-25 thing..." that might well resemble to the "U3" you found.

              Comment


                #8
                Re: Koban - Current Clamp Meter - DMM

                ut61e has nothing in common with those chips.

                Comment


                  #9
                  Re: Koban - Current Clamp Meter - DMM

                  Originally posted by stj View Post
                  mabe you can find a schematic for a similar meter with the same chip.
                  Semico CS7721CN
                  i also found this:
                  "The CS7721CN is pin for pin compatible with Fortune Semiconductor FS9721"

                  and a LOT of meter info is here:
                  https://sigrok.org/
                  Thank you stj, megaraider


                  2TY 2 - Emitter -> down -> 2 Layer, through hole.
                  2 - Emitter -> up , Left -> C letter ->
                  U3 pin 2 VSS -> C31

                  U3 - pin 1 (down) -> 2 Layer, through hole -> the other C31 pin

                  Testing U3 (Diode Mode) I get +- 0,56V
                  Other procedure to test this IC?

                  Regard,
                  Ruy
                  Last edited by neuron; 12-24-2020, 05:01 PM.

                  Comment


                    #10
                    Re: Koban - Current Clamp Meter - DMM

                    Originally posted by neuron View Post
                    Thank you stj, megaraider
                    (...)
                    Regard,
                    Ruy
                    Some thoughts:
                    U3 is an IC, see the attached image taken from the datasheet.
                    Follow the 5 pins traces back to the connected points and test if it`s working.

                    Q5 is most likely a transistor. Remove it from the board and test it.

                    C31 was a capacitor... value and type remain unknown.
                    From the previous, and compared to other similar schematics, you should be able to sort it out.
                    Attached Files

                    Comment


                      #11
                      Re: Koban - Current Clamp Meter - DMM

                      Originally posted by megaraider View Post
                      A very quick look pop-up UT61E (schematics) and Wintex TD2200, quite similar to UT61E. The later as "IC11: some tiny SOT-25 thing..." that might well resemble to the "U3" you found.
                      UT61E is ES51922 !!!
                      IC11 I can't find ...

                      DMM use Semico CS7721CN - Semico CS7721CN: UT60C, UT60A


                      Originally posted by megaraider View Post
                      Some thoughts:
                      U3 is an IC, see the attached image taken from the datasheet.
                      Follow the 5 pins traces back to the connected points and test if it`s working.

                      Q5 is most likely a transistor. Remove it from the board and test it.

                      C31 was a capacitor... value and type remain unknown.
                      From the previous, and compared to other similar schematics, you should be able to sort it out.
                      Diode mode?

                      2TY - I don't need remove from the board.
                      All my DMM can test Transistors in Boards.

                      And where I can find that schematics?

                      In your attach XC61xx.PNG the cap between Vin and ground ... value?

                      Ruy
                      Last edited by neuron; 12-25-2020, 07:16 PM.

                      Comment


                        #12
                        Re: Koban - Current Clamp Meter - DMM

                        Originally posted by neuron View Post
                        And where I can find that schematics?
                        In your attach XC61xx.PNG the cap between Vin and ground ... value?
                        Ruy
                        See datasheet here.

                        Comment


                          #13
                          Re: Koban - Current Clamp Meter - DMM

                          stj - the only info is MASTECH MS8250B (sigrok.org)







                          Originally posted by megaraider View Post
                          See datasheet here.
                          It's in japan. and no info about the cap ...

                          Comment


                            #14
                            Re: Koban - Current Clamp Meter - DMM

                            I wonder what happened so the PCB is so burned.
                            Useful conversions. I don't "speak" imperial. Please use metric, if you want to address me.
                            1km=1000m=100000cm, 1inch=2.54cm, 1mile=1609.344meters, 1ft=30.48cm 1gal(US)=3.785liters, 1lb=453grams, 1oz=28.34grams

                            Comment


                              #15
                              Re: Koban - Current Clamp Meter - DMM

                              Originally posted by televizora View Post
                              I wonder what happened so the PCB is so burned.
                              Only C31 Burn

                              I power up and tested all function
                              V, Ohm, Hz, Diode, ºC, ... don't see any errors
                              Zero, Hold, Select.

                              Ruy

                              Comment


                                #16
                                Re: Koban - Current Clamp Meter - DMM

                                Originally posted by megaraider View Post
                                See datasheet here.
                                Originally posted by neuron View Post
                                It's in japan. and no info about the cap ...
                                From the above datasheet, page 11:
                                4. Noise at the power supply may cause a malfunction of the watchdog operation or the circuit.
                                In such case, please strength the line between VIN and the GND pin and connect about 0.22μF of a capacitor between the VIN pin and the GND pin.


                                Comment

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