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DMM acting flaky

Discussion in 'Electronic Repair' started by ed, Feb 11, 2006.

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  1. ed

    ed Guest

    I've got a Rat Shack (micronta) 22-174B that I use for my hobby, which
    is building guitar effect pedals. It's a cheap unit, but it's got the
    functions that I need, such as a capacitance meter, hfe, etc.
    Anyhow, I can't get good ohm resistance readings at all anymore. It is
    way off. And the continuity tester beeps if I hold both a lead in each
    hand.
    I put in fresh batteries, the internal fuses are good, etc.
    Anyone has an idea?
     
  2. Ol' Duffer

    Ol' Duffer Guest

    Not very familar with the RS products, but many DMM's use
    a ratiometric configuration with the reference resistor in
    series with the unknown. You may have blown the reference
    resistor.
     
  3. Jerry G.

    Jerry G. Guest

    Peobably some of its referencing resistors are blown. Maybe someone put
    aome voltage through the meter while it was in the ohms mode. You will
    most likely need the service manual for the meter in order to service
    it. You will also need the parts source for the meter's parts. These
    resistors are generaly precision resistors. Using regular off the shelf
    ones would not be accurate.

    Jerry G.
     
  4. ed

    ed Guest

    Thanks for the reply, I'm trying to find a schematic and parts source
    for it, wouldn't you know, the Rat Shack is of little help.
     
  5. ed

    ed Guest

    Thanks for the reply, I'm trying to find a schematic and parts source
    for it, wouldn't you know, the Rat Shack is of little help.
     
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