Buick LeSabre 1965 Service Manual page 584

1 0 - 1 4 GENERATOR REPAIRS
ELECTRICAL SYSTEMS
HEAT SINK ^ ( ~ Y
DIODES \^y
K END FRAME
L \ DIODES
^4^
r
VPACITOR
SINK
BRUSH AND
TERMINAL
A S S E M B L Y - ^
SUP RINGS , - >
IP
BEARING"'~7
SEAL
/
DIODES
SLIP RING
END FRAME
THRU [ I t — I —
BOLT 7/tfHif
nATAfl - /
ROTOR
DRIVE
END FRAM
• n
31
Tffli
L,HO
•31
m
s J PULLEY
\ STATOR
J ASSEMBLY
Figure 10-8—Sectional View
b. Rotor Checks
The rotor may be checked elec-
trically for grounded, open or
short circuited field coils. To
check for grounds, connect a test
lamp from either slip ring to the
rotor shaft. See Figure 10-9. If
the lamp lights, the field winding
is grounded.
To check for opens, connect the
test lamp to each slip ring. If
the lamp fails to light, the winding
is open.
The field winding is checked for
short-circuits by connecting a
battery and ammeter in series
with the two slip rings. The field
current at 12 volts and 80°F.
should be between 2.2 and 2.6
amperes. An ammeter reading
above the specified value indi-
cates shorted windings.
If the rotor is not defective but
the generator failed to supply
rated output, the trouble is in the
stator or rectifying diodes.
c. Stator Checks
To check the stator windings, re-
move all three stator lead attach-
ing nuts, and then separate the
stator assembly from the end
frame. The fit between stator
frame and end frame is not tight,
and the two can be separated
easily.
The s t a t o r winding may be
checked with a test lamp. If the
(CHECK FOR GROUNDS)
(CHECK FOR OPENS)
lamp lights when connected from
any stator lead to the frame, the
windings are grounded. If the
lamp fails to light when succes-
sively connected between each
pair of stator leads, the windings
are open. See Figure 10-10.
A short circuit in the stator wind-
ings is difficult to locate without
laboratory test equipment due to
(CHECK FOR OPENS) /
(CHECK FOR OPENS) (CHECK FOR GROUNDS)
Figure 10-9—Checking Rotor
for Opens or Grounds
Figure 10-10—Checking Stator
for Opens of Grounds