7
Testing Diodes
Warning
• To avoid damage to the meter or to the devices under test, disconnect circuit
power and discharge all the high-voltage capacitors before testing diodes.
• Use the diode test mode to check diodes, transistors and other semiconductor
devices. In diode test mode, a current is sent through the semiconductor junction
and the voltage drop across the junction is measured.
• To test a diode out of a circuit, perform the following steps:
1. Insert the red test lead into the VΩHz terminal
and the black test lead into the COM terminal.
2. Turn the range selector to Ω. Press
SELECT to switch to diode measurement
mode.
3. For forward voltage drop readings on any
semiconductor component, connect the red
test probe to the component’s anode and the
black test probe to the cathode.
Notes:
• In a circuit, a good diode should still produce
a forward voltage drop reading of 0.5V to 0.8;
however, the reverse voltage drop reading can vary
depending on the resistance of other pathways
between the probe tips.
• The unit of diode is volt (V), displaying the forward voltage drop readings.
• To obtain a more precise reading, you could remove the object being measured
from the circuit when measuring.
• When diode testing has been completed, disconnect the test leads from the circuit
under test, and remove them from the input terminals.
3. Connect the test probes with the object being measured. The measured value
shows on the display.
Notes:
• Removing the object under test from its circuit will allow more accurate
measurement.
• When resistance measurement has been completed, disconnect the test leads
from the circuit under test, and remove them from the input terminals.
Measuring Continuity
• To test continuity, perform the following steps:
1. Insert the red test lead into the VΩHz terminal
and the black test lead into the COM terminal.
2. Turn the range selector to Ωand press
SELECT button to choose the continuity
measurement mode.
• The buzzer will sound if the resistance of a circuit
under test is less than 30Ω.
• The buzzer may sound if the resistance of a circuit
under test is between 30Ω and 100Ω.
