Onan MJA Series Service Manual page 112

110 REVOLVING ARMATURE GENERATOR
S.1.2 GENERATOR BEARlNG. - The generator bearing is prelubricated
for its life and sealed. It requires no servicing.
S.1.3 COMMUTATOR AND COLLECTOR RINGS. - The commutator
must be clean and in good condition.
If
it is dirty. clean with No. 00
sandpaper. Check the mica behveen the commutator bars.
If it
is
above the level of the bars under cut
it
(Sect
5.3.3).
For collector ring maintenance see Sect 5.}. 4
,
R EPt.A.CE ANY SR.USH
WORN TO
r
OR 1...ESS
FIG 5. B - SEATING BRUSHES
5.1.4 ANTI-FLICKER BREAKER
POINTS AND RESISTOR
(3MJA models). - The anti-flicker
breaker points are located on .the left
rear corner of
the
engine crankcase.
The camshaft opens these points on
every power stroke to add a resistor
in series with the generator field
windings. To adjust
the
breaker
points, crank the engine until the
points reach maximum separation.
Loosen and turn the stationary con ­
tact
to
set the gap at .025 in. Re­
tighten and recheck the gap.
4MJA models have a transistorized anti-flicker circuit. The transistor
shorts the flicker resistor (rather than the plunger and breaker pOints
used on 3MJA models) which will give long life to the breaker points
because current to its pOints is very low. The breaker points are used
only to contro I the transistor.
The adjustable flicker resistor is located on the right side of the control
box. If flicker becomes exceSSive, adjust the resistor by moving its
slider. Adjust
it
for minimum flicker with the average load on the plant.
Set gap at. 025"
FIG 6. C - ANTI-FLICKER BREAKER
POINT GAP