way connector. If a maroon colour lead is also used, leave this in position.
(2) Using the a.c. voltmeter with the one ohm. resistor across the ter-
minals (parallel) join one wire from the voltmeter to the white wire, the
other meter wire to the orange wire. Run the engine at a speed equivalent
to 30 m.p.h. in top gear, the voltage reading should be between 6.2 and
6.8 volts.
Transfer the meter wire from the orange wire to the light green and
repeat the test. A low reading on one of these tests indicates a fault in
the coils. A low reading on both tests can be due to a partially demagne-
tised rotor.
If no reading is shown on both tests, the alternator is defective (see
test 3).
(3) A short circuit to earth on one or more coils will affect the a.c.
voltage output.
To check, with the front chain case in position, use the d.c. voltmeter
in series with a battery in good condition. Connect the wire from the
meter to the white wire, the battery wire to a good and convenient earth
on the engine. If a reading is shown on the meter, one or both coils are
shorting to EARTH.
NOTE—The white wire is common to all coils.
Remove the outer portion of the chain case, check the alternator wires
for damaged insulation, also coil connections before discarding the alter-
nator,
When the fault is located, repeat the tests previously described.
Rectifier tests. Before testing, verify the earth connection is clean and
secure. Check also the wires attached to the rectifier for loose connec-
tions. Take out the white, green.and brown wires from the rectifier,
For this test use a 6 volt battery connected to a 3 watt bulb and holder.
Test in the following sequence:
NOTE —The common cause of rectifier trouble is invariably due to re-
versed battery connections, which can also demagnetise the rotor, if the
engine is run with these connections reversed. The battery positive ter-
minal is connected to EARTH (translucent), the negative is the feed line
(brown).
Ignition and lighting switches. Both switches in the head lamp are
Positive wire to Light Green
White
Brown
Brown
Bulb earthed. Bulb lights.
Rectifier O.K.
Bulb on Green. No light.
Bulb on White. No light.
Rectifier faulty.
Bulb earthed. No light. Rectifier
O.K.
Bulb on Green. Bulb lights.
Bulb on White. Rectifier faulty.
Reverse the battery connections with:
Negative wire to Light Green
White
Brown
Brown
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