Yamaha XS650 Series, Shop Manual

Page: 91 / 215

*ELECTRICAL
A. IGNITION SYSTEM
1
1
protective circuit
2. Description
This model is equipped with a battery
operated, fully transistorized breakerless
ignition system. By using magnetic pick-
up coils the need for contact breaker
points is eliminated. This adds to the
dependability of the system by eliminat-
ing frequent cleaning and adjustment of
points and ignition timing. This TCI
unit incorporates an automatic advance
circuit controlled by signals generated by
the pick-up coils. This adds to the
dependability of the system by eliminat-
ing the mechanic advancer. This TCI
system consists of two main units; a
pick-up unit and an ignitor unit.
3. Operation
The TCI functions on the same principle
as a conventional DC ignition system
with the exception of using magnetic
pick-up coils and a transistor control box
(TCI) in place of contact breaker points.
a. Pick-up unit
1. Pick-up unit
This unit consists of two pick-up coils
mounted on the generator case and a
permanent magneto on the rotor which
is mounted to the crankshaft. When the
magneto passes through these pickup
coils, the signals are generated at the
pick-up coils and forwarded to the
ignitor unit as a signal.
The full ignition advance is determined
by the distance (or angle) between two
pick-up coils.
b. lgnitor unit
lgnitor
unit unit)
This unit has such functions of wave
form, duty control, switching, and elec-
trical ignition advance. The ignition
timing is advanced electrically using two
signals from the pick-up coils.
The duty control circuit is provided to
control the on time period of the pri-
mary ignition current to reduce the
electrical consumption. This unit also
incorporates a protective circuit for the
ignition coil. If the ignition switch is
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