Generator Overhaul CS-144

This section is applicable only to the CS-144 generator. The CS-130D generator cannot be overhauled. Refer to Generator Usage .

Tools Required

J 39200 Digital Multimeter

1. Scribe a mark in the frame end parts in order to help locate the parts in the same position during re-assembly.
2. Remove the 4 through-bolts.

Notice: On models with a slip ring end ball bearing on the rotor shaft, this bearing must be replaced with a new bearing any time the two halves of the generator are separated. If not replaced, the bearing may bind and fail due to distortion of its outer tolerance rings. This does not apply to roller-type slip ring end frame bearings.

3. Separate the rotor and drive end frame assembly from the slip ring end frame assembly.

Notice: The rotor may be distorted if the vise is overtightened.

4. Place the rotor in a vise. Tighten the vise to the rotor only enough in order to allow removal of the pulley nut.



5. Remove the following parts from the rotor shaft:

•

The nut

•	The washer

•	The pulley

•	The collar

•

The fan

•	The outside collar

6. Remove the drive end frame and the inside collar from the rotor shaft.

1. Remove the 3 nuts that secure the stator to the rectifier bridge.
2. Remove the stator from the slip ring end frame .
3. Unsolder the following connections to the voltage regulator:

•	The connector strap

•	The brush holder




4. Remove the insulated screw from the brush holder.
5. Remove the voltage regulator screw.
6. Remove the brush holder with the dust shield.
7. Remove the voltage regulator from the slip ring end frame.



8. Remove the following components from the brush holder:

•	The brushes

•	The dust shield

9. Clean the brushes with a soft, dry cloth.



10. Remove the rectifier bridge and capacitor as a unit:

10.1.

Remove the bolts.

10.2.

Remove the washers.

10.3.

Remove the rectifier bridge and capacitor assembly.




11. Remove the slip ring end frame bearing.

1. Clean all of the metal parts in a suitable solvent except for the following components:

•	The voltage regulator

•	The rectifier bridge

•	The stator

•

The rotor

•	The bearing assemblies

2. Wipe or blow dry the parts.
3. Remove the dust shield and brushes from the brush holder.
4. Inspect the brush holder for damage.
5. Inspect the brush springs for a broken wire or corrosion.
6. Inspect the brushes for wear.

•	If the brushes are worn to 11 mm (0.4 in) or less in length, replace the brush holder assembly.

•	Use a retainer pin to hold the brushes in the holder.

7. Inspect the slip ring end of the rotor shaft for overheating or scoring.

•	If signs of overheating or scoring are present, replace the rotor.

•	Any time the 2 halves of the generator are separated, replace the slip ring end bearing.

8. Inspect the drive end bearing for roughness, looseness, or wear. If the condition of the bearing is in doubt, replace the generator drive end frame.
9. Inspect the windings for burned insulation.

•	Replace the rotor or the stator if either of these look burned.

•	Burned insulation appears as very dark or blackened wiring. A strong acidic odor will be apparent.

10. Inspect the terminal connectors for corrosion or breaks.
11. Inspect the windings on the stator for chipped insulation.

If the chipped area is small, and the rest of the stator is operating properly, repair the stator with insulating varnish.

12. Inspect the slip rings for scoring, wear, or pitting.

12.1.

If the rings are dirty, clean the rings with 400 grain or finer polishing cloth.

12.2.

Spin the rotor. Hold the polishing cloth against the slip rings until the rings are clean.

12.3.

Blow all dust away.

12.4.

If the rings are scored, worn, or pitted, replace the rotor.

13. Inspect the generator housing for cracks, warping, or other damage.



14. If needed replace the following components:

•	The regulator

•	The brush assembly

•	The connector

15. Unsolder the regulator from the other 2 components. Use as little heat as possible in order to protect the regulator.

1. Connect a J 39200 DMM (1) from one slip ring to the rotor shaft. Measure the resistance. Refer to Generator Usage . If the reading is less than specified, the rotor winding is grounded. Replace the rotor.
2. Connect a J 39200 DMM (2) from one slip ring to the other slip ring. Measure the resistance. Refer to Generator Usage . If the reading is greater than specified or infinite, the winding is open. Replace the rotor.

1. Connect a J 39200 DMM from any stator lead to bare metal on the stator frame. Measure the resistance. If the J 39200 does not read infinity, the stator is grounded. Replace the stator if the stator is grounded.

A J 39200 cannot be used to test for open stator windings or shorts between windings because the stator is delta-wound.

2. Inspect the stator assembly for noticeable discoloration. Discoloration usually indicates an abnormal condition in the stator windings. Replace the stator if the stator shows discoloration.

Important: Some digital ohmmeters cannot be used in order to test diodes in the rectifier bridge. Consult the ohmmeter manufacturer in order to determine the capabilities of your ohmmeter.

1. Connect a J 39200 DMM to the grounded heat sink and one of the 3 terminals.
2. Place the J 39200 DMM in the diode test position.
3. Press down firmly on the flat metal clip.
4. Observe the diode reading.
5. Reverse the J 39200 lead connections to the grounded heat sink and the same metal clip. If both readings are the same, replace the rectifier bridge. A good rectifier bridge will give one high and one low reading.
6. Repeat this procedure between the grounded heat sink and the other 2 terminals, and between the insulated heat sink and each of the 3 terminals. This makes a total of 3 tests, with 2 readings taken for each test.

The regulator cannot be tested outside of the generator. Replace the regulator if any of the following conditions apply:

1. Install the bearing into the slip ring end frame from the outside.
2. Ensure that the bearing is flush with the outside shoulder of the slip ring end frame.




Important: In order to ensure proper operation of the generator, install the slip ring end frame components in the correct order.

3. Install the rectifier bridge.

Important: Install the capacitor with the insulator material contacting the end frame.

4. Install the capacitor.
5. Install the washers.

Important: Ensure that the insulated bolt attaches the capacitor strap and the rectifier bridge to the slip ring end frame. Ensure that the metal side of the capacitor strap is contacting the regulator connection.

6. Install the bolts.



7. Install the brushes into the brush holder with the retaining pin.
8. Install the dust shield onto the brush holder.



9. Install the following components into the slip ring end frame as one unit:

•	The voltage regulator

•	The brush holder

10. Ensure that the brush retaining pin extends through the end frame access hole when the brush holder is in place. After the rotor and the drive end frame are installed, the pin will be removed, allowing the brushes to contact the slip rings.
11. Install the regulator bolt.
12. Install the brush holder bolt.
13. Assemble the connector strap to the voltage regulator solder clip. Assemble the brush holder connection to the other voltage regulator solder clip.

Notice: Avoid excessive heat when soldering connections, as this can cause voltage regulator damage.

14. Crimp, then solder, the voltage regulator connections.



15. Install the stator into the end frame. Align the 3 stator leads to the 3 rectifier bridge terminals.
16. Install the 3 rectifier bridge nuts. Tighten the nuts securely.

1. Install the inside collar onto the rotor.
2. Install the rotor into the drive end frame.




Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

3. Install the following components onto the rotor shaft:

•	The outside collar

•

The fan

•	The fan collar

•	The pulley

•	The washer

•

The nut

Tighten
Tighten the generator pulley nut to 100 N·m (74 lb ft).

1. Connect the drive end frame and rotor assembly to the slip ring end frame. Lining up the marks.
2. Install the 4 through-bolts. Tighten the bolts securely.
3. Remove the brush retainer from the end frame.
4. Test the generator output. Refer to Generator Assembly Bench Check .