Electrical System; Transistorized Ignition System - Arctic Cat Sno Pro 120 2013 Service Manual

Electrical System

TESTING COMPONENTS
Following are testing procedures for specific electrical
components. All tests of the electrical components
should be made using the digital Fluke Model 77 Multi-
meter. Replace any component that does not have a test
value within specifications.
 NOTE: Whenever using a digital-style tester, "open
(infinite resistance)" denotes an overload and the meter
reading will be OL since the meter is not calibrated to
register resistance values of that magnitude.
 NOTE: Whenever testing switches, less than 1 ohm is
desirable with the switch in the activated position.
 NOTE: Always check the appropriate fuse before test-
ing a component for failure.
Transistorized Ignition
System
The transistorized ignition system has no contact points.
Therefore, this ignition system does not require periodic
reconditioning of contact point surfaces or point gap
adjustment. As a result, a strong spark is produced even
at low speeds so maximum reliability can be ensured.
OPERATION
When the recoil starter handle is pulled, the flywheel is
turned. An electromotive force generated in the primary
winding of the ignition coil makes the transistor (TR1)
conduct through the resistor (R) and forms the primary
circuit (indicated by dashed lines).
As the flywheel turns faster, the primary current
increases, and the terminal voltage of the circuit consist-
ing of the resistor (R) and the transistor (TR1) increases.
This increases the working voltage at the connection of
the series circuit (r1 + r2) connected in parallel to the pri-
mary circuit. As the flywheel turns further, the terminal
voltage of the resistor (r2) in the resistor circuit (r1 + r2)
rises to the level of working voltage of the transistor
(TR2) when the ignition timing approaches the rated
RPM, and, thus, the transistor (TR2) is turned on. As a
result, the base current of (TR1) flowing through the
resistor (R) is by-passed, and the transistor (TR1) is
turned off from the conductive state.
The current flowing through the primary winding (2) is
thus interrupted, and rapid change occurs in the magnetic
flux across the ignition coil. The result is a high surge
voltage in the secondary winding (3).
SPARK ADVANCE CHARACTERISTIC
As noted above, the unit circuit detects a voltage and
makes switching to produce a high voltage required to
produce a spark. On the other hand, the wave form of the
voltage generated in the primary winding changes as the
flywheel turns.
The working voltage (VS) of the unit circuit is at level A
when the engine is started, but as the engine speed
increases, the wave form of the voltage changes and
advances to level B.
TROUBLESHOOTING
1. Remove the spark plug and visually check its condi-
tion. Replace if fouled. Adjust spark plug gap to
0.028-0.031". Attach the high tension lead to the
GEN-0008
spark plug and ground the plug on the cylinder head.
 NOTE: Make sure the emergency stop switch is in the
ON (UP) position, the ignition switch is in the RUN posi-
tion, and the tether cord is connected to the tether switch.
2. Crank the engine over and check for a spark. If no
spark is present, disconnect the main wiring har-
ness from the engine. Crank the engine over. If
spark is now present, the problem is either one or
more of the following items.
A. Defective ignition switch
B. Defective emergency stop switch
C. Defective wiring harness
GEN-0009
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