Onan MJA Series Service Manual page 126

124
1
CONTROL SYSTEM
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ANKS ENGINE
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STARr IGNITION CURRENT TO
CENTRIF(/GAL
RELAY ENERGIZED IGNITION COIL
ENGINE
AND ELECTRIC
STARTS
SW/ICH CLOSES
CHOKE
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IGNITIONRELAY
-OPENS START
A748
ENGINt: RUNS­
PULLS IN­
IGNITION RELAY
STARTING CYCLE
AND MAINTAINS
ENDED
CURRENT TO IG­
NITI ON SYSTEM.
FIG 6.D - STARTING CYCLE, REVOLVING FIELD,
REMOTE START
Test the relay by checking contact continuity, energized and de-ener ­
gized, and coil resistance. Coil resistance is abou t 76 ohms.
6.3.1. 2Ignition Relay
(4f307B623). -
This relay is normally energized
throughout plant operation. It energizes, when the centrifugal switch
ending the starting cycle closes, and maintains the current to the engine
ignition system. To test the relay, inspect the contacts, check the con ­
tinuity of each set of contacts, and measure the coil resistance. Coil
resistance is about 15 ohms.
CAUTION: This is a 6 volt relay and in the control circuit it is in
series with a 15 ohm dropping resistor.
6.3.1. 3 Centrifugal Switch. - The centrifugal switch is mounted on the
gear cover backplate with the ignition breaker points, and operates
directly off the camshaft gear. Normally open, the switch closes when'
the engine speed builds up about 900 rpm.
For correct operation maintain the switch contact gap at . 020 in. (Fig
6.E)
Check the contacts for dirt or pitting when adjusting the gap. Clean
the contacts with paper or replace it
if
badly pitted.
Tn
an emergency, if the centrifugal switch won't operate, the engine can
be run by shorting the switch leads when the engine starts.