Carrier 69UG15 manual c. Diode Testing, b c. d e, Bearing Replacement, 6 Rectifier Removal

c. Diode Testing

The rectifier diode assemblies can be tested, and if damaged, replaced. Over current, over voltage, over speed, or reverse currents can damage the assembly or diodes. To remove the diode assemblies and perform diode testing, do the following:

1.Remove the bearing cover by removing the four bolts (see Figure 4-6). Both the bearing and diode assemblies will be visible.

3.	Remove the two cap screws that secure each diode
	assembly to the exiter. Once this procedure is
	complete, the diode assemblies are free for removal.
4.	A forward diode should have a low resistance when
	the + of an ohm meter is connected to the exciter
	rotor lead connection (anode) and the - to the diode
	bridge (cathode), and a high resistance when the
	polarity of the ohmmeter is reversed.
5.	A reverse diode should have a high resistance when
	the + of an ohm meter is connected to the exciter
	rotor lead connection (anode) and the - to the diode

a.

g.

f.

b.

c.d.

e.

bridge (cathode), and a low resistance when the

polarity of the ohmmeter is reversed.

6. If both resistances are high or both are low, the diode

is defective and the diode assembly should be

replaced.

4.5.3 Bearing Replacement

When operated under normal conditions, factory--lubricated shielded bearings will normally provide years of trouble--free service. Excessive bearing load and adverse environment conditions will greatly shorten bearing life. To remove the bearings, do the following:

a. Rectifier Flange	e. Bearing Cover Bolt
b. Rectifier Assembly	f. Bearing
c. Rectifier Bolt	g. Bearing Cover Flange
d. Bearing Cover

Figure 4-6 Rectifier Removal

2.Mark and disconnect the alternator rotor wires at the rectifier screw terminals. Note that the terminals are marked with red paint for the forward diode assembly and black for the reverse diode assembly. Mark and disconnect the exciter leads from the double spade

terminals (see Figure 4-7).
a.	a.
	b.
d.
c.
b.	d.

a.Diode Assembly

b.Diode Bridge

c.Exciter Rotor Lead Connection

d.Alternator Rotor Lead Connection

Figure 4-7 A-C Generator Rectifier Assembly

1.Remove bearing cover (See Figure 4-6).

2.Remove bearing with a bearing or wheel puller.

3.Install new bearing. Ball bearings are pre-lubricated and require no additional lubrication for the life of the bearing.

4.Coat mating surface of bearing cover flange with anti-corrosion compound (Tef-Gel, Carrier Part Number 02-00083-00). Replace bearing cover.

4.5.4Generator Removal and Installation a. Removing the Generator

1.Remove covers and ground wire from frame of generator set.

2.Remove connection box cover and disconnect power leads.

3.Remove screen cover and generator exhaust baffle from coupling end of generator.

4.Remove the six 8mm hex head bolts and washers that secure the generator drive disc to the engine flywheel. Turn bolts counter-clockwise with offset wrench to start, then use flexible shaft and socket assembly for removal of bolts.

5.Remove the twelve 3/8 inch hex head cap screws and washers that secure generator frame to engine flywheel housing.

6.Remove the four 5/8 inch bolts that secure the generator mounting feet to the shockmount bracket, then remove generator.

b. Installing the Generator

NOTE

For torque values refer to paragraph 4.7.

T--343 4--8