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Still floundering with the Zenith

Discussion in 'Electronic Repair' started by Silver Surfer, Sep 7, 2004.

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  1. Should I be able to use an ordinary DMM to measure the continuity on the
    high voltage windings of the flyback on my Zenith SF2037W? From the low end
    of the winding to the high end are two diodes in series. There is a focus
    takeoff between the two. Can't read anything from the focus tap to the high
    end. Also cannot read anything from the low end to the high end. Read
    about 1100 ohms from the focus to the low end both polarities. Might just
    be parallel resistance in the circuitry if my meter is not capable of making
    the diodes conduct.
  2. gothika

    gothika Guest

    You really need a flyback and yoke tester.
  3. James Sweet

    James Sweet Guest

    HV diodes will need a higher voltage than a DMM can provide in order to be
    tested. Best way to test a flyback is a ring tester, they're only about $40,
    worthwhile if you work on TV's occasionally.
  4. Andy Cuffe

    Andy Cuffe Guest

    1100 ohms from the focus to ground is definitely bad. There's
    normally around 2-5 kV on the focus output of the flyback. That would
    mean thousands of watts being dissipated in the flyback!
    Andy Cuffe
  5. OK. Let's say that I don't have any special equipment for testing the
    flyback. Could I draw upon automotive technology by inserting a DC current
    into the primary winding then opening the "points" to produce a high voltage
    pulse on the output? Just a crude test to find out if the flyback has any
    life at all in it.

    Forgot to mention that the transformer is still soldered in the circuit.
    That might explain the 1100 ohms reading on the focus "tap."
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