On 12 Mar 2007 19:12:49 -0400 Sam Goldwasser
wrote in Message id: :

writes:

For a definitive measurement, don't test the diode in place. Rather,
unsolder one of its leads from the circuit board and then test it with
your voltmeter's continuity checker.

If it tests good in-place, it won't test bad when removed.

Unless the in-circuit test is turning on a junction of another
semiconductor that's in the same circuit, and the diode is open.