UNI-T UT58E Operating Manual page 19

Measurement Operation(6)
Warning
To avoid damage to the Meter or to the equipment
under test, disconnect circuit power and discharge
all high-voltage capacitors before measuring diodes.
To avoid harms to you, never attempt to input voltages
higher than 60V DC or 30V rms in AC
Measuring Diodes
Use the diode test to check diodes, transistors, and other
semiconductor devices. The diode test sends a current
through the semiconductor junction, and then measures
the voltage drop across the junction. A good silicon junction
drops between 0.5V and 0.8V
Note
l In a circuit, a good diode should still produce a forward
voltage drop reading of 0.5V to 0.8V; however; the
reverse voltage drop reading can vary depending on
the resistance of other pathways between the probe
tips.
l Connect the test leads to the proper terminals as said
above to avoid error display. The LCD will display "1"
indicating open-circuit for wrong connection. The unit
of diode is Volt (V), displaying the positive-connection
voltage-drop value.
Model UT58E: OPERATING MANUAL
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