Theory Of Operation; Capacitor Charging #1 Cdm - Mercury 40 Service Manual

Theory of Operation

This outboard ignition system is alternator driven
(distributor-less) capacitor discharge system. Major
components of the ignition system are the flywheel,
stator, trigger, capacitor discharge modules (CDM's)
and spark plugs. Each capacitor discharge module
functions as a combination switchbox and secondary
ignition coil.
CAPACITOR-
COIL-
SCR-
DIODE-
a - Battery Charging Coils
b - Trigger Coils
c - Capacitor Charge Coils
d - CDM #1
e - CDM #2
2A-8 - ELECTRICAL
a
S
N
N
S
3
+
_
_ N S
1
+
+
2
_
N
S
N
S
j YEL
YEL
BLK
BRN
Return Voltage
Source Voltage

Capacitor Charging #1 CDM

The STATOR assembly is mounted to the block be-
low the flywheel and has 3 CAPACITOR CHARGING
COILS wound in series. The FLYWHEEL is fitted with
6 permanent magnets inside the outer rim. The fly-
wheel rotates the permanent magnets past the ca-
pacitor charging coils causing the coils to produce
AC voltage (260–320 volts). The AC voltage is then
conducted to the CAPACITOR DISCHARGE MOD-
ULES (CDM), where it is rectified (DC) and stored in
a capacitor. The stator voltage return path is through
the ground wire of the other CDM and back through
that CDM's charging coil wire to the capacitor charg-
ing coils.
b
S
N
S
N
c
WHT/GRN
GRN/WHT
WHT
i
BLK/YEL
f - CDM #3
g - Rev. Limiter (Not Used On All Models)
h - To Ignition Switch
i - Stop Switch
j - To Voltage Regulator
d
e
f
PPL
g
BLK
h
90-852572R1 JANUARY 1998