Testing reset IC ncp803sn293 & 2sc3052 NPN Transistor

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  • Chaks
    Senior Member
    • Sep 2015
    • 115
    • India
    #1

    Testing reset IC ncp803sn293 & 2sc3052 NPN Transistor

    I am trying to trouble shoot the power-detect part of the circuit see attached images and my readings are as below. can anyone suggest me if the IC and NPN transistor is working properly. The TV resets automatically when switched on.

    Q7502 2sc3052 npn transistor has the following readings.
    Base +lead to emitter -lead = 0.6v
    Base +lead to collector -lead =0.6v
    Emitter +lead to base -lead =over limit
    Collector +lead to base -lead = over limit

    Collector +lead to emitter -lead = 0.98 volts
    Emitter +lead to collector -lead = 0.68 volts

    POWER DET circuit:

    IC 7509 ( ncp 803 sn293)

    Pin 3 vcc to ground of PCB is 3.5 volts
    Resistance between pin vcc and reset pin 2 is 100k ohms
    The TV resets when pin 1 gnd or pin 2 reset is touched by multimeter leads pos or neg.

    IC 7510 (ncp 803 sn293)
    Pin vcc to ground of PCB is 0.9 volts
    Pin 3 vcc to gnd pin 1 is 1.9 volts
    Resistance between vcc and reset pin is 355k ohms
    Pin 1 gnd and pin 2 reset pin (+lead) is 3.6 volts
    Reset pin to ground of PCB is 1.2 volts

    Is there anything faulty here? Power-det circuit is on page 35 of the service manual.
    The service manual of TV is also attached.
    Attached Files
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