testing diodes       


Testing a diode is relatively simple if you have a digital multimeter.
Set the multimeter to diode test and connect the diodes for forward bias .......

black probe to
cathode ( - )


red probe to
anode (+)

the meter should show (around)

1.8 volts for LEDs
this will vary with the different colours!! as the different semiconductor mixes have different forward voltages


0.65V for Silicon diodes


0.2V for Germanium diodes
(use germanium as a semiconductor substrate)

 its that simple!

If you find readings that do not indicate a healthy diode it has probably been overloaded!!
Its always best to test an electronic component out of the circuit.

If you do not have a digital multimeter but have an analogue meter then check forward and reverse resistance using the ohmmeter.