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8-24
ALTERNATOR AND REGULATOR-DIAGNOSIS
PART 3
ALTERNATOR A N D VOLTAGE REGULATOR
ALTERNATOR
SERVICE DIAGNOSIS
Condition
Possible Cause
Correction
ALTERNATOR FAILS TO
CHARGE (No Output)
(a) Blown fusible wire in voltage regulator.
(b) Alternator drive belt loose.
(c) Worn brushes and/or slip rings.
(d) Sticking brushes.
(e) Open
field
circuit.
(f) Open charging circuit.
(9) Open circuit in stator windings.
(h) Open rectifiers.
LOW,
UNSTEADY
CHARGING RATE
(a) Alternator drive belt loose.
(b) High resistance at battery terminals.
(c) High resistance in the charging circuit.
(d) High resistance in the body
to
engine ground
(e) Open stator winding.
lead.
LOW OUTPUT AND
A LOW BATTERY
(a) High resistance in the charging circuit.
(b) Low regulator setting.
(c) Shorted rectifier. Open rectifier.
(d) Grounded stator windings.
EXCESSIVE CHARGING
RATE
TO
A FULLY
CHARGED BATTERY
(a) Regulator set too high.
(b) Regulator contacts stuck.
(c) Regulator voltage winding open.
(d) Regulator base improperly grounded.
(a) Locate and correct the cause of the fuse blow-
ing. Install a new fuse wire. Solder both ends
of a new fusible wire securely.
(b) Adjust the drive .belt according to specifications.
(c) install new brushes and/or
slip
rings.
(d) Clean the slip rings and brush holders. Install
new brushes.
(e) Test all the field circuit connections, and cor-
rect as required.
(f)
Inspect all connections in the charging circuit,
and correct as required.
(9) Remove the alternator and disassemble. Test
the stator windings. Install a new stator
if
nec-
essary.
(h) Remove the alternator and disassemble. Test
the rectifiers. Install new rectifiers
if
necessary.
(a) Adjust the alternator drive belt.
(b) Clean and tighten the battery terminals.
(c) Test the charging circuit resistance. Correct as
required.
(d) Tighten the ground lead connections. Install a
new ground lead
if
necessary.
(e) Remove and disassemble the alternator. Test
the stator windings. Install a new stator
if
necessary.
(a) Test the charging circuit resistance and correct
as required.
(b) Reset the voltage regulator according to speci-
fications.
(c) Perform the current output test. Remove and
disassemble the alternator. Test the rectifiers.
Install new rectifiers as required.
(d) Remove and disassemble the alternator. Test
the stator windings. Install a new stator
if
necessary.
(a) Reset the voltage regulator according to speci-
(b) Install a new voltage regulator.
(c) Install a new voltage regulator.
(d) Connect the regulator base to the ground con-
fications.
nection.
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