Matco Tools MD251 Guia Del Usuario página 7

6
 Resistance,
Continuity, Diode test functions
Press the SELECT button momentarily to select the subject functions in sequence. Last selection
will be saved as power up default for repeat measurement convenience.
CAUTION
Discharge capacitors before making any measurement. Large value capacitors should be
discharged through an appropriate resistance load.
CAUTION
Using resistance and continuity function in a live circuit will produce false results and may damage
the instrument. In many cases the suspected component must be disconnected from the circuit to
obtain an accurate reading
Continuity function is convenient for checking wiring connections and operation of switches. A
continuous beep tone indicates a complete wire.
Normal forward voltage drop (forward biased) for a good silicon diode is between 0.400V to
0.900V. A reading higher than that indicates a leaky diode (defective). A zero reading indicates a
shorted diode (defective). An OL indicates an open diode (defective). Reverse the test leads
connections (reverse biased) across the diode. The digital display shows OL if the diode is good.
Any other readings indicate the diode is resistive or shorted (defective).