General Tools and Instruments DMM333 - Manual (Page 22)

4.If the polarity of the test leads is
reversed with diode polarity, the
display reading shows “OL”.
This can be used to distinguish
the anode and cathode sides
of a diode.
5.For silicon diode, forward bias
voltage should be 0.5
∼0.8V,
for germanium diode, forward
bias voltage should be 0.2
∼0.3V.
A “0 V” reading in both directions
indicates a shorted diode.
An “OL” reading indicates an
open diode. In either case, the
diode is defective and should
be replaced.
red test lead black test lead
22