what to check when replacing pwm IC

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  • tukidid
    Member
    • Jan 2011
    • 11
    #1

    what to check when replacing pwm IC

    Can you replace bad ob2269(SMPS not clicking any longer and chip has about few V on pin 3 VIN although in front of it there is 310V) with sg6841 or ld7552 or some other without modifying circuit around it(except for the sw. frequency setting resistor) as the one at

    What should one check Zfb,Zcs first, or missing leading edge blanking block and one diode after fb input?
    (real ob2269 circuit has different component values and in addition resistor divider at MOS gate and one more diode+capacitor in front of VDD)

    Tags: None
    • Toasty
      Badcaps Legend
      • Jul 2007
      • 4171
      #2
      Re: what to check when replacing pwm IC



      Why are you replacing the chip?

      Is this a theoretical question or are you working on an actual circuit?

      If so, post unit info and pictures.

      Values in datasheet diagrams are examples for that particular sample circuit. Not for all the circuits that use that particular chip.

      Toast
      veritas odium parit

        Comment

        • tukidid
          Member
          • Jan 2011
          • 11
          #3
          Re: what to check when replacing pwm IC

          it is hp 18.5v,3.5a notebook supply and ob is not readily available

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