Diode Test - Mastech my68 Instruction Manual

The Meter's resistance ranges are 400.0 Ω , 4.000k Ω ,
40.00kΩ, 400.0kΩ, 4.000MΩ and 40.00MΩ.
To measure resistance:
1. Set the rotary switch to Ω Ω Ω Ω range.
2. Connect the black and red test leads to the COM and
Ω terminals respectively.
3. Connect the test leads to the circuit being measured
and read the displayed value.
Some tips for measuring resistance:
¥
The measured value of a resistor in a circuit is often
different from the resistor's rated value. This is because
the Meter's test current flows through all possible paths
between the probe tips.
¥ In order to ensure the best accuracy in measurement of low
resistance, short the test leads before measurement and
memory the test probe resistance in mind. This necessary to
subtract for the resistance of the test leads.
¥ The resistance function can produce enough voltage to
forward-bias silicon diode or transistor junctions, causing
them to conduct. To avoid this, do not use the 40MΩ range
for in-circuit resistance measurements.
¥ On 40M Ω range, the meter may take a few seconds to
stabilize reading. This is normal for high resistance
measuring.
¥ When the input is not connected, i.e. at open circuit,
the figure "OL" will be displayed for the overrange
condition.
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3.2.3 3.2.3 Diode Diode Test Test
3.2.3 Diode 3.2.3

Diode Test

Test
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Use the diode test to check diodes, transistors, and other
semiconductor devices. The diode test sends a current
through the semiconductor junction, then measures the
voltage drop across the junction, A good silicon junction
drops between 0.5V and 0.8V.
To test a diode out of a circuit:
1. Set the rotary switch to
/ / / /
2. Press the key to activate Diode Test.
3. Connect the black and red test leads to the COM and
VΩ terminals respectively.
4. For forward-bias readings on any semiconductor
component, place the
component's anode and place the black test lead on
the component's cathode.
5. The meter will show the approx. forward voltage of the
diode.
In a circuit, a good diode should still produce a forward bias
reading of 0.5V to 0.8V; however, the reverse-bias reading
can vary depending on the resistance of other pathways
between the probe tips.
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