Pontiac FIREBIRD 1972 Service Manual page 787

ENGINE ELECTRICAL 6E-25
I
SINGLE CONNECTOR
THREE CONNECTORS
Fig. 6E-35 Checking Diode Trio (SI)
d. Stator which fails above test should be replaced.
4. If necessary, stator may be cleaned by brushing with
oleum spirits.
CAUTION: Do not clean in solvent.
5. The stator can be installed by reversing steps 1 and
2.
DIODE TRIO (SI ONLY)
The diode trio is identified in Fig. 6E-23. Before removing
the diode trio, connect an ohmmeter, using lowest range
scale, from brush lead clip to end frame as shown in Fig.
6E-32, then reverse lead connections. If both readings are
zero, check for grounded brush lead clip caused by omis-
sion of insulating washer (Fig. 6E-32), omission of insulat-
ing sleeve over screw, or damaged insulating sleeve.
Remove screw to inspect sleeve.
To remove diode trio, proceed as follows:
1. Remove three stator attaching nuts.
2. Remove stator.
3. Remove diode trio lead clip attaching screw and
remove diode trio. Note that the insulating washer on
the screw is assembled over the top of the diode trio
connector.
To check the diode trio, after removing it from the end
frame assembly, connect an ohmmeter having a 1 1/2
volt cell to the single brush connector and one of the
stator lead connectors (Fig. 6E-27). Observe the read-
ing on the lowest range scale. Then reverse the leads
to the same two connectors. Repeat this test with
each of the other two stator lead connectors. If any
or all give readings when reversing connections
which are the same, replace the diode trio. A good
diode trio will give one high and one low reading.
CAUTION: Do not use high voltage, such as a
110 volt test lamp, fo check this unit.
RECTIFIER BRIDGE (SI AND 10 DN)
The rectifier bridge contains all of the diodes found in the
heat sink and slip ring end frame of the generator. If one
diode is defective, the entire rectifier bridge must be re-
placed.
To check the rectifier bridge, connect an ohmmeter to the
ground heat sink and base of one of the three terminals
(Fig. 6E-36). Then reverse the connections to the
BRUSH
HOLDER REGULATOR
I
HEAT SINK
GRou'NDED
I
-
I
u
OHMMETER
Fig. 6E-36 Checking Rectifier Bridge Diodes