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hissing chopper

Discussion in 'Electronic Repair' started by BigTom, Jan 8, 2005.

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  1. BigTom

    BigTom Guest

    Panasonic tc-63R50N color tv

    HOT ok. 106v at Collector.
    no HV
    no heater.
    sound ok.
    can change channels + adjust volume.

    this set has a separate p/s board using an STR51213.
    tested resistance on this ic, no pins shorted.

    the chopper is making a squealing noise while turned on.

    done the usual, esr caps, checked all the big resistors, transistors.

    what should i look at next?
  2. JURB6006

    JURB6006 Guest

    The noisy chopper might be normal if there is no horizontal drive. It's
    probably supposed to be locked to the line rate and there's nothing for it to
    lock onto.

    I'd look into why there is no drive.

  3. CJT

    CJT Guest

    You've got a TV with a chopper? I've never seen such a thing.

    Maybe you mean something in the horizontal output section?
  4. JURB6006

    JURB6006 Guest

    Maybe you mean something in the horizontal output section?

    No, chopper is sorta slang for the output device in a switched mode power
    supply, or the entire power supply itself.

    (unless there are long forks sticking out of the front)

  5. CJT

    CJT Guest

    It seems odd (to me) to re-use a term that already applies to a
    different electronic device.
  6. James Sweet

    James Sweet Guest

    What device? The only electronics I've ever heard "chopper" apply to is the
    switching transistor in a SMPS.
  7. CJT

    CJT Guest

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