Trouble Shooting And Repairs; Spare Parts - Nomenclature - MarelliMotori M8B 315 Instructions And Safety Information

6. TROUBLE SHOOTING AND REPAIRS

TROUBLE
The alternator will not
energise (no load voltage
below 10% of rated
voltage)
The alternator will not
energise (no load voltage
20-30% of rated voltage.
Voltage insensitive to AVR
potentiometer's rotation
Voltage lower then rated
(output voltage between 50
and 70%)
Voltage too high
Unstable voltage
7.SPARE PARTS – NOMENCLATURE
Pos Part Name
201 D side (D:E) bearing
202 N side (N.D.E.) bearing
6 Voltage regulator
12 Varicomp
7 Fuse 10A-500V (6,3x32)
309 Rotating diode (inverse)
310 Rotating diode (direct)
311 Surge suppressor
307 Filter
308 Surge suppressor
119 Complete rotating rectifier
POSSIBLE CAUSE
a) Loose connections
b) Rotating diodes or surge suppressor
broken
c) Excitation circuit shorted or interrupted
a) Fuse (on AVR's supply line) blown
b) Connection's cut on the exciter stator
c) Incorrect connections of exciter stator
a) Speed less than rated
b) Voltage potentiometer unset
c) Fuse blown
d)Faulty regulator
a) Potentiometer V unset
b) Faulty regulator
a) Diesel engine rpm variations
b) Stability potentiometer unset
b) Faulty regulator
M8B 315
6319 C3 / 346151095
6315-Z C3 / 346113275
REMEDY
(always to be done with the machine switched off)
a) Check and repair
b) Check the diodes and change in case they are open or
shortcircuited
c) Check the continuity and repair
a) Replace the fuse with the spare. If the fuse blows again
check if the exciter stator is short circuited. If everything is
correct, change the AVR
b) Check the continuity and repair
c) Reverse the two wires from the exciter stator
a) Check rpm (frequency)
b) Rotate the potentiometer until the voltage reaches the
rated value
c) Replace the fuse with spare
d)Disconnect AVR and replace it
a) Rotate the potentiometer until the voltage reaches the
rated value
b) Replace AVR
a) Check rpm uniformity. Check the diesel engine governor
b) Act on AVR's stability potentiometer.
b) Replace AVR
Type / Code
M8B 400
6324 C3 / 346151120
6318-Z C3 / 346113290
M40FA610A
M40FA621A
963823010
71 HFR 120 / 963821170
71 HF 120 / 963821171
M40FA990A
M40FA500A
19
ENGLISH
M8B 500
6328 C3 / 346151140
6326 C3 / 346151130
71HFR 120 / 963821056
71 HF 120 / 963821057
M50FA873A
963827007
M50FA301A