John Deere stx38 - Manual (Page 134)

ELECTRICAL CIRCUIT OPERATION AND DIAGNOSIS
4 - 50
3/21/97
CHARGING CIRCUIT DIAGNOSIS STX38 (SN 210001— ) & STX46
Test Conditions:
• Brake engaged • Engine running at fast idle
• Regulator/rectifier connector disconnected • Meter negative (-) lead on battery negative (-)
terminal
• Key switch in run position • Meter positive (+) lead on numbered test point
Test/Check Point Normal If Not Normal
1. Battery positive terminal . 11.8-13.2 volts Test battery
2. Regulator/rectifier connector
(between white wires).
Minimum unregulated voltage output
— 28 VAC. Check flywheel magnets, if OK
replace stator.
Test Conditions:
• Regulator/rectifier connector connected
Test/Check Point Normal If Not Normal
3. Regulator/rectifier center
terminal (black wire).
Battery voltage Check battery positive cable
connections, and 220 red wire.
4. Regulator/rectifier black wire. Minimum regulated output—
13 amps at 12.2—14.7 volts.
Voltage must stay below 14.7 volts.
Replace regulator/rectifier .
Replace regulator/rectifier.