Trouble Shooting And Repairs; Spare Parts - Nomenclature - MarelliMotori M8B 250 Instrucciones Y Advertencias De Seguridad

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 – PART NAME
Pos.
Part nam e
201 D side (D:E) bearing
202 N side (N.D.E.) bearing
6 Voltage regulator
12 VARICOMP device
7 Fuse (6.3 A, 250 V)
309 Rotating diode (inverse)
310 Rotating diode (direct)
311 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.
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
6218 C3 / 346110114
6313 2RS C3 / 346245065
M25FA645A
M40FA621A
963823040
41 HFR 80 / 963821160
41 HF 80 / 963821161
M25FA921A
M25FA464A
15
ENGLISH