John Deere stx38 - Manual (Page 149)

3/21/97
4 - 65
ELECTRICAL TESTS AND ADJUSTMENTS
REGULATED VOLTAGE OUTPUT
TEST
Reason:
To determine regulated voltage output of the regulator/
rectifier.
Equipment:
• Voltmeter
Connections:
1. Remove surface charge from battery by cranking
engine for 15 seconds.
2. Connect meter red lead to positive battery terminal.
3. Connect meter black lead to negative battery
terminal.
Procedure:
1. Start and run engine at HIGH IDLE.
2. Read meter several times during 5 minutes of
running time.
Specifications:
Regulated voltage . . . . 12.2—14.7 VDC at high idle
Results:
• If the DC voltage stays below the minimum
specification or does not increase, test
Unregulated Voltage Output in this group.
• If the DC voltage goes above the maximum
specification, replace the regulator.
UNREGULATED VOLTAGE OUTPUT
TEST
Reason:
To measure stator voltage output to determine stator
condition.
Equipment:
• Voltmeter
Connections:
1. Disconnect regulator/rectifier connector (A).
2. Set voltmeter to AC voltage.
3. Connect meter across outside terminals.
Procedure:
1. Start and run engine to specifications.
2. Measure stator voltage.
Specifications:
Export—
Engine speed. . . . . . . . . . . . . . . . . . . . . . .3000 rpm
Minimum stator voltage . . . . . . . . . . . . . 24 VAC
Domestic—
Engine speed. . . . . . . . . . . . . . . . . . . . . . .3350 rpm
Minimum stator voltage . . . . . . . . . . . . . 28 VAC
Results:
• If reading is less than specifications, test
FLYWHEEL MAGNET and then replace the stator.
• If stator voltage is OK, check charging circuit wires,
then replace regulator/rectifier.
M55942
M55944
A