Robin America EH63, Service Manual

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8. ELECTRIC SYSTEM
OPERATION AND FUNCTION
The ignition system is pointless flywheel magneto with automatic advancing characteristic.
Being different from the breaker point type ignition system, this system is completely free from such troubles as
starting-up failure owing to dirty, burnt or corroded point surface.
The electronic automatic advancing ensures extremely easy starts and stable high performance at operating
speed by advancing the ignition timing to the most suitable point.
BASIC THEORY
(1) Revolution of the flywheel generates electricity on the primary side of the ignition coil, and the base current
I
1
flows to the power transistor. Current I
1
turns the power transistor "ON" and the electric current I
2
flows.
(2) At lower engine revolution, when the flywheel reached the ignition point the low speed ignition timing control
circuit operates to run the base current
I
3
to turn the signal transistor A "ON" allowing the current
I
1
to
bypass as current
I
4
.
At this moment the power transistor turns "OFF" and the current
I
2
is abruptly shut resulting in the high
voltage generated in the secondary coil which produces sparks at the spark plug.
Low Speed
Ignition
Timing
Control Circuit
I
3
I
4
Signal Transistor
A
Automatic
Advancing
Control
Circuit
I
5
I
6
Signal Transistor
B
I
1
Resister
I
2
Power Transistor
Secondary Coil
Primary Coil
Spark plug
500 1000 2000 3000 (r.p.m.)
ENGINE REVOLUTION
IGNITION TIMING
STEP ADVANCING
ELECTRONIC ADVANCING FLYWHEEL
MAGNETO SYSTEM
(B.T.D.C.)