Chevrolet 70 1969 Series, Shop Manual

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ENGINE ELECTRICAL 6Y-22
F ig u re 2 — 6 2 - A m p . G e n e ra t o r In sta lle d (T yp ica l)
5. Pry between stator shell and slip ring end frame to
force end frame off rotor shaft rear bearing assembly.
Do not cock frame excessively as it is pried off. Fig­
ure 10 shows slip ring end frame removed from gener­
ator. Note that capacitor and relay leads must pass
through opening in end frame as end frame is re­
moved and must remain with the stator assembly.
6. Remove three bolts, lock washers, and special nuts
which attach drive end frame to stator shell. Separate
stator and shell assembly from drive end frame and
rotor assembly.
7. Remove the shaft nut, washer, pulley, and W oodruff
drive key (fig. 4); slide the drive end frame and two
spacers off the shaft.
NOTE: Further disassembly is not required un­
less inspection and tests indicate necessity for
parts replacement.
BENCH-TESTING GENERATOR
COMPONENTS (ELECTRICAL)
ROTOR CHECKS (Fig. 5)
Rotor may be checked for grounded winding either by
use of test lamp or with an ohmmeter.
Checking for Ground With Test Lamp. Touch one test
lamp lead to one of the slip rings and other lead to rotor
pole or shaft. If lamp lights, the winding is grounded and
rotor assembly must be replaced.
Checking for Ground With Ohmmeter. M ake test in
same manner as with test lamp and observe reading. If
reading is low, indicating low resistance, the winding is
grounded and rotor assembly must be replaced.
Checking for Open Circuit With Test L am p or O hm ­
meter (fig. 5). Touch the leads from lamp or ohmm eter to
End Fram e “ B a t” Term inal
Field Term inal / \
C a p a cito r R e la y Term inal
TPM 9815-1
F ig u re 3 — R e a r V i e w o f 6 2 - A m p . G e n e ra t o r (T yp ica l)
each of the slip rings. If lamp fails to light or ohmmeter
reading is high (infinite), the winding is open.
Checking for Shorted Winding in Rotor Assembly. Ei­
ther of two methods may be used to check rotor winding
for shorts as described below.
1. A m m eter and Battery Method. Connect 12-volt bat­
tery and am m eter in series with the two slip rings.
Note am m eter reading. If reading is over 4.4 a m ­
peres, there is a short circuit in winding.
2. Ohm m eter Method. Connect ohm m eter leads to the
two slip rings and note the resistance reading. If the
resistance is less than 2.7 ohms, there is a short cir­
cuit in rotor winding.
NOTE: If an ohmmeter is not available, the re­
sistance can be calculated by dividing the volt­
age by the current (amperes) using values from
previous Step 1.
If there are no defects found in the rotor assembly and
generator does not produce rated output when checked as
directed in “ Generator Output Test,’’ trouble is in either
the stator assembly or in the rectifying diodes.
Stator Checks (Fig. 6)
Since the connections at diodes and stator leads are sol­
dered and it is necessary to disconnect stator leads for
some of the tests, only properly trained technicians with
approved equipment should attem pt to make the checks at
stator windings described following:
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L