[TenTec] ORION BCI

[Stuart Rohre]

Although rare, diodes could exhibit other effects than open or short or
normal.  It might NOT show up with barrier voltage test of diode section of
DMM but might show up if you view the circuit signals with a scope.  Depends
on how the protective diodes are configured, whether they are in series with
a resistor.   And it might not be the internal diode connection, but the
external solder joint, in fact; much more likely.  One could shotgun the
solder by reheating joints, if magnifier inspection shows any suspect
joints.
Heat sink the lead at the diode body for protection of it.  This indeed
might be what happened, someone did not have the assembly correct with heat
sinking.

The resistors need to be checked as well, if present.
-Stuart
K5KVH