(5) Place one of the rest wires on to one of the two coil terminals, the
other to the coil case. No reading should show. Use the test wires on the
h.t. connection and the case. No reading should show.
A meter reading on one or both tests means the windings are earthed,
the coil should be replaced.
Usually a defective primary winding will produce a weak spark, con-
versely, an intermittent spark is associated with a faulty secondary wind-
ing. Where doubt exists, test by substitution.
The condenser (see 'Ignition system'). If the condenser is suspect, use a
sound condenser with two crocodile clips attached to it.
Remove contact breaker cover, attach one clip to the connection on
the contact breaker terminal, the other to a conventional earth position.
Running the engine with the external condenser in use will prove if
the condenser is faulty or otherwise.
Vivid blue arcing at the contact points is indicative of a faulty con-
denser.
Where the orthodox electrical testing gear is not available, improvisa-
tion can be made using the following equipment:
(1) A 6 volt 36 watt bulb and holder.
(2) A ft volt .04 amp bulb and holder (this bulb is used on cycle rear
lamps).
(3) A fully charged 6 volt battery.
(4) A short length of wire to join the battery to one side of the bulb
holder. Also two test wires about 24" long connected to the other battery
and bulb holder terminals.
Test to ensure the bulb lights then proceed by:
Disconnecting the alternator wires from the connector.
Join one test lead to the white cable, the other test wire to the green
cable.
Run the engine at a fast tick over speed when the bulb should show a
fairly bright light.
Transfer the test wire from the green cable only to the orange cable
and repeat the test.
Conclusions from test
(1) If the lamp bulb is not uniformly lighted on both tests, there is a
fault in the alternator (see 'Earth test').
(2) Should the bulb fail to light, the alternator is defective.
(3) A dull light on both tests indicates a partially demagnetised rotor,
due to battery connections being reversed at some time or other. Use a.c.
voltmeter to check voltage output.
Alternator coils earthed. Use the test set with the 6 volt .04 bulb.
Connect one test wire to a convenient earth position on the engine.
Connect in turn, the other test wire to the white, green and orange
wires,
Should the bulb light on any of these tests, the coils are shorted to
earth.
Rectifier (forward flow test). With the ignition and lights switches 'OFF',
use the 36 watt bulb for this test, then;
Disconnect the wire from the brown connector on the rectifier (keep
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