Inspection And Repair - Hummer H1 Service Manual

12-24 Electrical System
Alternator Parts
Cleaning
Use part cleaning solvents on metal parts only. The insulating
coatings on wires in the field coil and stator can be damaged by
cleaning solvents.
Clean encapsulated and exposed wire items by wiping with a
clean cloth.

Inspection and Repair

Rotor
Inspect for cracked slip rings, damaged threads, and galling or
scoring on bearing journal surfaces on shaft (Figure 12-39).
Corrosion or light scoring on the slip rings may be removed
with 400 grit emery cloth.
Test the slip rings and field coil for opens (high resistance),
shorts (very low resistance), and grounds (low resistance) to
frame and shaft. Replace the rotor if a fault is detected.
Inspect the ball bearing for free play, roughness, leaking seals,
and other damage. Replace the bearing if necessary. Seat the
new ball bearing against the rotor shoulder.
WINDINGS
SHOULDER
BALL
BEARING
SLIP RINGS
Figure 12-39: Rotor Inspection Points
4-1-00
_______________________________________________________
Stator
Check the stator leads for continuity to ground (laminations).
Any continuity indicates a grounded stator which should be re-
placed (Figure 12-40).
Examine the stator winding for discoloration due to overheat-
ing or short to ground. Normal color is reddish brown to pur-
ple. Bare copper, dark spots, or dull black color indicates
burned spots.
Replace the stator if damaged, shorted or grounded.
SHAFT
Rectifier Bridge
Test the rectifier bridge as follows:
THREADS 1. The bridge studs are embedded in insulation. To obtain
2. Connect the ohmmeter leads to the grounded side and
3. Repeat step 1 with test leads reversed.
4. All three readings in steps 1 or 2 should read high
5. Connect ohmmeter leads on positive side and strap as
6. Repeat process of step 4 with leads reversed.
7. All three readings in steps 4 and 5 should be the same,
8. If any one reading in steps 1, 2, 3, and 4 is not the same as
STATOR LEADS
Figure 12-40: Stator Inspection Points
diode readings, the ohmmeter leads must contact the cop-
per strap.
strap as shown and take readings at each strap
(Figure 12-41).
resistance in one case and low resistance in other case.
shown, and take readings at each strap (Figure 12-41).
with resistance high in one set and low in the other set.
the other two readings, replace rectifier bridge.
®
STATOR
WINDINGS
LAMINATIONS