Onan MJA Series Service Manual page 102

100
REVOLVING FIELD GENERATOR
4.3.2.4 Collector Rings. - If the collector rings are grooved, out-of­
round, pitted. or rough so that good brush seating can't be maintained,
remove the rotor, Sect 4.4. and refinish the rings in a lathe. Remove
or shield the ballbearing during refinishing.
4.3.2.5 Ballbearing. -
If
the ballbearing becomes noisy, worn Or other­
wise defective. replact it. Remoy€ the old ballbearing with a gear pull ­
er and drl\'e or press a new one into place.
I - I
j:J"t ,
~c
!
~ II
-----II---'--:::>~
\,- I
J \
L- _ _
..-J
(...TRANSFORM£R WITH
SEPARATE PRIMARV ANO
SECONf)ARY-I:
t
FOR SAFeTY
" ­
FIG 4.K - 115 V CONTINUITY TEST LAMP (Use for testing Magneciter)
4.3.3 MAGNECITER TESTING AND REPAIR. - If generating failure is
traced to the Magneciter, see the Magneciter trouble-shooting chart.
Perform tests on the components with either an ohmmeter or a 115 volt .
test lamp (Fig. 4.K).
Always isolate the component being tested by removing its leads. Be­
fore testing, make certain that no part of the Magneciter is grounded.
Use the tests in the following sections to determine whether the com­
ponents are functioning properly. Replace any components found de­
fective.
4.3.3.1 Reactors. - Test the control reactor with an ohmmeter, using
the resistance values in the Table of Resistances (Fig. 4. L). Use the
following method to test each gate reactor:
1. Make certain that no part of the Magneciter is grounded.
2.
Is.olate the gate winding (G V G2) by disconnecting one lead from
its point of connection and the control winding by disconnecting both
leads (C
1
, C 2 ) from their pOints of connection.
CAUTION: The accuracy and reliability of resistance values de­
pends on the accuracy of the ohmmeter used. Relia ­
ble readings such as found between G 1 and G2 can't be
accurately read with a multirfJeter.