Diode testing
- Thread starter jackecole
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Most modern multimeter's have a Diode test function which measures the threshold voltage. So overload reading one way and voltage the other i.e. silicon will be 0.6 volts. On a circuit board likely you will need to lift a leg.
However looking at the circuit some times one can see there is nothing else likely to effect the reading and one can take 0.6 volts as good and 0 or infinity in both directions as faulty.
The problem is we have no idea of type or use the diode. My sons boat has diodes in the shore line earth which are doubled up and back to back so will measure 1.2 volts in both directions.
With older multi-meters you use the ohms range. The reading means nothing and you just look for needle moving in one direction and not in the other. But old multi-meters used 1.5 to 22 volts to test ohms. New ones use less than 0.6 volt so on ohm range will show all diodes as open circuit.
However looking at the circuit some times one can see there is nothing else likely to effect the reading and one can take 0.6 volts as good and 0 or infinity in both directions as faulty.
The problem is we have no idea of type or use the diode. My sons boat has diodes in the shore line earth which are doubled up and back to back so will measure 1.2 volts in both directions.
With older multi-meters you use the ohms range. The reading means nothing and you just look for needle moving in one direction and not in the other. But old multi-meters used 1.5 to 22 volts to test ohms. New ones use less than 0.6 volt so on ohm range will show all diodes as open circuit.
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