Gilera SATURNO BIALBERO 350 Workshop Manual page 112

BATTERY CHARGING CIRCUIT
Rectifier check
It is a three-phase rectifier.
Check the diode's efficiency by disconnecting the connector end (fig. 3):
Connect the positive (+) prod of the ohmmeter to the red wire and the
negative (-) one to the white wires (one at a time) (fig. 4). With efficient
diodes, the pointer should not move.
The same operation must be carried out on the black wire and the positive
(+) prod on the white wires (always one at a time). With efficient diodes,
the pointer should not move.
If during the test the ohmmeter's pointer moves, this means that the diode
considered is short-circuited.
To check if one of the diodes is discontinued, repeat same operation being
careful to reverse the prods of the ohmmeter and checking that the pointer
shows a resistance of 1000 ÷ 1500 Ω.
Alternator stator coil check
Disconnect the alternator wires (fig. 5)
Remove the alternator stator coil.
Check for continuity between the two wires of the alternator stator coil
(fig. 6).
Check for continuity between the wires of the alternator stator rectifier
(fig. 7).
Check if there is no continuity, on the contrary, between the above
mentioned stator coil wires and ground (figs. 8-9).
In case of no continuity between the stator coil and rectifier wires or if, vice
versa, in case of continuity between wires and ground, the stator itself
should be replaced.
TROUBLESHOOTING
No voltage with the key in the "ON" position
Dead battery
Disconnected battery cable
Main fuse blown
Defective ignition switch
Low voltage with the key in the "ON" position
Weak battery
Battery incorrectly connected
Defective charging system
Low voltage with engine running
Insufficiently charged battery
Malfunction in the charging circuit.
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