Chevrolet Chevelle 1967 Overhaul Manual page 153

DELCOTRON 6Y-9
generator to avoid undue strain on the lead wire.
5. Remove three slip ring end frame attaching bolts and
tab nuts.
6. Carefully pry the end frame and case apart (using a
screw driver) slowly all the way around the circum-
ference to remove the end frame.
7. Remove the three drive end frame attaching bolts
and tab nuts and remove the end frame, rotor and
pulley as an assembly.
8. Remove shaft nut, washer, pulley and woodruff key
from rotor shaft, then slide rotor from end frame.
9. Remove drive end frame bearing retainer plate and
bearing from end frame.
10. To remove slip ring end frame bearing from rotor
shaft, use Tool J-6627 as shown in Figure l i e .
11. Disconnect the three stator leads by cutting the leads
between coil and diodes. An alternate method is to
scrape epoxy coating from lead connections and un-
solder stator leads, using a minimum amount of
heat to avoid damage to diodes.
NOTE: Separating these three leads will allow
diode and stator tests outlined in this section.
12. Remove heat sink-to-case retaining screws and r e -
move heat sinks. Insulated heat sink (with batt
terminal) holds positive diodes.
CLEANING A N D INSPECTION
With generator completely disassembled, except for
removal of diodes, the components should be cleaned and
inspected. Be sure testing equipment is in good working
order before attempting to check the generator.
1. Wash all metal parts except stator and rotor as-
semblies.
2. Clean bearings and inspect for sealing, pitting or
roughness.
3. Inspect rotor slip rings, they may be cleaned with
400 grain polishing cloth. Rotate rotor for this op-
eration to prevent creating flat spots on slip rings.
4. Slip rings which are out of round may be trued in a
lathe to .001" maximum indicator reading. Remove
only enough material to make the rings smooth and
concentric. Finish with 400 grain polishing cloth and
blow dry.
5. Slip rings are not replaceable--excessive damage
will require rotor assembly replacement.
6. Inspect brushes for wear. If they are worn halfway,
replace. Inspect brush springs for distortion or
weakening. If brushes appear satisfactory and move
freely in brush holder, springs may be reused.
TESTING ROTOR
The rotor may be checked electrically with a 110-volt
test lamp or an ohmmeter.
Grounds
Connect test lamp or ohmmeter from either slip ring
to the rotor shaft or to the rotor poles. If the lamp lights
or if the ohmmeter reading is low, the field windings are
grounded (fig. 5c).
Opens
Connect one test lamp or ohmmeter lead to each slip
ring. If the lamp fails to light or if the ohmmeter reading
is high, the windings are open (fig. 5c).
(CHECK FOR GROUNDS)
OHMMETER
OHMMETER
(CHECK FOR SHORTS AND OPENS)
Fig. 5c—Checking Rotor for Grounds or Opens
Short Circuits
The windings are checked for shorts by connecting a
12 volt battery and an ammeter in series with the two
slip rings. Note the ammeter reading. An ammeter
reading above the specified field amperage draw indi-
cates shorted windings. Refer to Specifications at the end
of this manual.
TESTING STATOR
Grounds
Connect a 110-volt test lamp or an ohmmeter from any
stator lead to the stator frame. If test lamp lights or if
ohmmeter reads low, the windings are grounded (fig. 6c).
Opens
If lamp fails to light or if ohmmeter reads high when
successively connected between each pair of stator leads,
the windings are open (fig. 6c).
Short Circuit
A short in the stator windings is difficult to locate
without special test equipment due to the low resistance
of the windings. However, if all other electrical checks
are normal and the generator fails to supply rated out-
put, shorted stator windings are indicated. Also, look
for heat discoloration on the windings.
TESTING DIODES
Two methods may be used to check diodes for shorts
or opens, a test lamp of not more than 12 volts or an
ohmmeter.
CAUTION: Do not use a 110-volt test lamp to
test diodes.
TEST LAMP METHOD
Diode in Heat Sink
With the stator previously disconnected connect one of
the lamp leads to the heat sink and other lead to the diode
CHEVROLET CHASSIS OVERHAUL MANUAL