Loader Bobcat 773. Manual - part 73

ALTERNATOR

Test the alternator as follows:

a. Alternator Output Test
b. Rectifier (Diode) Test
c. Alternator Regulator Test

Alternator Output Test

Lift and block the loader. (See Page 1–1.)

Disconnect the negative (–) cable from the battery.

Disconnect the red wire (Item 1) [B] from the alternator.
Connect that wire to the negative (–) side of the ammeter.

Connect the positive (+) side of the ammeter to the output
terminal on the alternator (Item 2) [B].

Disconnect the fuel stop solenoid connector.

Connect the negative (–) cable to the battery.

Turn on the lights and crank the engine for 30 seconds to
discharge the battery.

Connect the fuel stop solenoid, start the engine and run
at 2600 RPM.

The ammeter reading should be between 45–55 amps. at
2600 RPM.

If the reading is low, remove the bolts and pull the
regulator cover away from the alternator.

Rectifier (Diode) Test

The alternator is removed from the loader for clarity
purposes [C].

Disconnect the negative (–) cable from the battery.

Install the wires in their original location on the back of the
alternator.

Connect a jumper wire (Item 1) [C] to the alternator output
terminal and the regulator terminal.

Connect the battery negative (–) cable.

Start the engine and run at 2600 RPM.

If the reading is within 45–55 amps. at 2600 RPM replace
the rectifier (diode) assembly or replace the alternator.

If the reading is low, do the Alternator Regulator Test.

NOTE: The photo’s may be different but the

procedure is the same for all models.

Put jackstands under the front axles and rear
corners of the frame before running the engine
for service. Failure to use jackstands can allow
the machine to fall or move and cause injury or
death.

W–2017–0286

MC–01813

REAR VIEW OF ALTERNTOR

P–01304

Output

Terminal

Regulator

Terminal

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773 BICS Loader

Service Manual

P–02284

When an engine is running in an enclosed
area, fresh air must be added to avoid
concentration of exhaust fumes. If the engine
is stationary, vent the exhaust outside.
Exhaust fumes contain odorless, invisible
gases which can kill without warning.

ALTERNATOR (Cont’d)

Alternator Regulator Test

W–2050–1285

Connect the positive (+) voltmeter lead to the positive (+)
battery terminal [A].

Connect the negative (–) voltmeter lead to the negative
(–) battery terminal [A].

Start the engine and run at 1500–2000 RPM.

The voltmeter should read between 13.9–14.7 volts.

If the reading is low stop the engine and disconnect the
battery negative (–) cable.

The alternator is removed from the loader for clarity
purposes [B].

Remove the wires from the back of the alternator.

Remove the regulator cover from the back of the
alternator.

Install the wires on the back of the alternator.

Connect a jumper wire (Item 1) [B] from the brush
terminal to the ground stud.

Connect the negative (–) battery cable and start the
engine. Run at 1500 RPM.

If the voltmeter reading is 14.5 or above replace the
regulator.

If the voltmeter reading is below 14.5, repair or replace the
alternator.

P–02282

Positive

Negative

773 BICS Loader

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Service Manual

P–01364

Ground

Stud

Brush

Terminal

Raise the operator cab. (See Page 1–1.)

Disconnect the negative (–) cable from the battery.

Disconnect the red wire (Item 1) [A] from the alternator
which comes from the battery.

Disconnect the wiring harness connector (Item 2) [A]
from the alternator.

Remove the adjustment bolt (Item 3) [A] from the
mounting bracket.

Remove the alternator belt from the alternator pulley.

Remove the mounting bolt (Item 4) [A] and spacer (Item
5) [A].

Adjusting The Alternator Belt

Stop the engine.

Raise the operator cab. (See Page 1–1.)

Loosen the alternator mounting bolt (Item 4) [A].

Loosen the adjustment bolt (Item 3) [A].

Move the alternator until the belt has 5/16 inch (8,0 mm)
movement at the middle of the belt span with 15 lbs. (66
N) of force.

Tighten the adjustment bolt and mounting bolt.

Lower the operator cab.

ALTERNATOR (Cont’d)

Removal And Installation

Place jackstands under the rear corners of the loader.

Never work on a machine with the lift arms up
unless the lift arms are secured by an approved
lift arm support device. Failure to use an
approved lift arm support device can allow the
lift arms or attachment to fall and cause injury
or death.

W–2059–0598

Revised Jan. 99

Raise the lift arms and install an approved lift arm support
device. (See Page 1–1.)

•

Engine is operated with battery cables
disconnected.

•

Battery cables are connected when using a
fast charger or when welding on the loader
(Remove both cables from the battery).

•

Extra battery cables (booster cables) are
connected wrong.

Damage to the alternator can occur if:

I–2023–1285

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773 BICS Loader

Service Manual

P–03877

ALTERNATOR (Cont’d)

Disassembly And Inspection

Disassemble the alternator. (See Parts Identification
Figure [A].)

Remove the regulator cover and regulator.

Remove the four bolts holding halves together.

Pry the halves apart (use a press if needed).

Use a soft jaw vise to hold rotor while removing pulley nut.

Remove front case half from the rotor using a plastic
hammer or press.

Unsolder the stator leads from the rectifier. Remove the
stator.

Stator Continuity Test

Use an ohmmeter to test the stator.

Touch the probes to two of the bare stator wires [B].

Move one of the probes to the third wire.

The readings should be the same.

If there is no continuity, replace the stator.

Stator Ground Test

Touch one probe to a bare stator lead and the other probe
to the bare metal surface of the stator [C].

There should be no continuity.

Replace the stator if there is continuity.

C–03312

1. Nut

9. Rectifier (Diode)

2. Pulley

10. Case Half (Rear)

3. Fan

11. Condenser Assy.

4. Bolt

12. Strap

5. Case Half (Front)

13. Regulator

6. Bearing

14. Brush

7. Rotor

15. Cover

8. Stator

P–01369

P–01386

773 BICS Loader

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Service Manual

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