Yamaha XS750-2D Supplemental Service Manual page 15

0: Continuity
Even of one of elements is broken,
replace assembly.
CAUTION:
The silicon rectifier can be damaged if
subject to overcharging. Special care
should be taken to avoid a short circuit
and/or incorrect connection of the posi-
tive and negative leads at the battery.
Never connect the rectifier directly to
the battery to make a continuity check.
X:
Discontinuity (=-)