Toshiba 37bv701b power supply main rails

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  • semiRocket
    Member
    • Jan 2013
    • 25
    • Croatia

    #1

    Toshiba 37bv701b power supply main rails

    The set is not turning on, when buttons on the front are pressed the button press sound is coming from the speakers, but the set is not trying to turn on, consuming only couple of watts.

    I am troubleshooting a Vestel 17PW26-5 from the set. Not sure how it is supposed to turn on main supply, but with the main board disconnected not getting the main supply to turn on either.

    Standby supply is working, PFC is working (390V), but the main supply is dead. Checked the mosfets and driving transistors and found they are not shorted and showing a diode junction. The suspicious part is the half-bridge self oscillating driver ic NCP1392B. I found a very low resistance (2 ohms) between IC GND and Mlower pins, do you think this is normal. By looking at IC block diagram there should be a mosfet between GND and Mlower.

    The IC is getting 11.7V on VCC, 1.3V on BO pin.
    Attached Files
  • thommyX
    Senior Member
    • Apr 2016
    • 96
    • Germany

    #2
    No, that's not correct. Replace the IC and then it should work again.

    LG Thomas

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