Do not allow the voltmeter reading to rise above 10 volts.
Do not race the engine in an attempt to increase the voltage. It is suffi-
cient to run up the engine to a speed of 1,000 r.p.m.
If the above reading is obtained the dynamo is in order.
If there is no reading, check the brush gear.
If there is a low reading of approximately ½ volt, the field winding may
be at fault.
If there is a low reading approximately 1½ to 2 volts, the armature
winding may be at fault.
If the tests, mentioned above clearly indicate the dynamo is not charg-
ing, it is then desirable to remove the dynamo from the machine in order
to make further tests and repairs or replacements.
To remove the dynamo (before 1957).
Remove the left side foot rest arm.
Place a tray under primary chaincase to catch the oil.
Remove chaincase band binding screw and remove metal band and also
endless rubber band.
Remove nut and washer in centre of chaincase when outer half can be
taken away.
Remove spring circlip, locking plate and nut securing dynamo sprocket
and withdraw sprocket with a suitable tool (Use spanner 017254 to hold
sprocket while nut is being slackened, this relieves the dynamo shaft of
all bending strain.)
Detach dynamo cables and loosen dynamo clamping bolt to fullest
extent.
Twist dynamo by hand until the locating strip on its body is in line
with the keyway cutaway in the rear engine plate housing the dynamo, in
which position same can be withdrawn tilting upwards to clear gear box
while doing so.
To re-fit the dynamo, reverse the foregoing taking care to accurately
locate the dynamo sprocket key when applying the sprocket. See separate
instructions for correct dynamo chain adjustment and re-fitting outer half
of chaincase. Ensure that dynamo sprocket securing nut is well tightened
before refitting locking plate and retaining circlip.
A.V.C. UNIT
Although the voltage regulator and the cut-out are combined structu-
ally, they are electrically separate.
The regulator is set to maintain a pre-determined generator voltage at
all speeds and regulates the output of the dynamo to the battery accord-
ing to the state of charge of the battery. The charge rate is at its maximum
when the battery is discharged, automatically tapering off to a minimum
as the battery becomes charged and its voltage rises.
Normally, during day-time running, when the battery is in good condi-
tion, the dynamo gives only a trickle charge, so that the ammeter reading
will seldom exceed 1 to 2 amperes, i.e. half to one division on scale. The
cut-out is an automatic switch which is connected between the dynamo
and the battery. When the engine is running fast enough to cause the
voltage of the dynamo to exceed that of the battery the cut-out allows the
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