Replacement of Mercedes Benz alternator parts

Mercedes Benz Alternator

Alternator and regulator Bosch and internal regulator

Description

The Bosch alternator is a conventional 3-phase self-rectifying alternator.

Bosch’s 75-55 amp alternator uses three negative, three positive diodes and a diode connected to the stator winding to rectify the current. Bosch 90 and 80 amp alternators use 14 diodes.

All alternators use three excitation diodes connected to the stator windings. While the engine is running, these diodes turn off the alternator indicator lights and power the voltage regulator.

Alternator application

Model volt / amp

(1) Manufacturer’s part number

190E 14/70 489928

190D 14/70 489 897

All others 14 / 70N / A

(1) The Bosch alternator part number is preceded by a number 0 120 or begins with AL and ends with an X.

1. You can connect the voltmeter to the alternator’s “B +” terminal and ground. If you do not check the wiring between the battery and the alternator, the voltmeter should indicate the battery voltage.

2. Turn on the ignition and check that the alternator indicator light is on. If the light does not turn on, check the wiring between the warning light and the alternator (including the indicator bulb).

1. Make sure the battery, alternator, and starter connections are clean and secure, make sure the alternator engine and body are properly grounded, and the alternator belt is in good condition. Make sure.

2. Connect the ammeter according to the manufacturer’s instructions, and connect the lead wire of the voltmeter to the battery terminal.

3. Start the engine and run at 3000 RPM to adjust the carbon pile for maximum alternator output. Make sure the voltage does not drop below 12.6 volts.

4. The alternator output should be equal to the alternator’s rated output minus 16 to 20 amps. If the reading is 16-20 amps below the alternator rating, replace the regulator and retest. If the output is still too low, repair or replace the alternator.

Regulator control voltage test

1. Connect the ammeter according to the manufacturer’s instructions, connect the voltmeter lead to the battery terminal and run the engine at 3000 RPM

2. Run the engine until the voltage stops rising. The voltage should be between 13.5 and 14.5 volts. If the reading is incorrect, remove the regulator and make sure the brush is longer than 6mm.

3. If the brush is okay and the regulator cannot keep the voltage within the specified limits, replace the regulator and retest. If the voltage is still incorrect, repair or replace the alternator.

overhaul

Disassembly

1. Remove the nut, lock washer and pulley, remember the spacer position, then remove the fan assembly and key, scribe the front and rear housing marks, remove the voltage regulator and screws, remove the front and rear housings. Separate

2. Remove the capacitor from the terminal. Remove nuts, insulators, screws and washers.

Remove the stator assembly.

3. Solder the stator from the diode assembly. Remove the bearing wave washer or O-ring from the back of the housing.

3. Support the front housing and carefully push out the rotor. Prevent the rotor from falling, remove the screws that secure the bearing retainer, remove the front bearing of the retainer, and seal the rear bearing from the slip ring at the end of the rotor.

Testing and repair

Diode assembly

1. Place the ohmmeter scale on the x100 scale and connect the ohmmeter leads to the “B +” terminal and the three stator terminals one at a time. Reverse leads and ohmmeters need to show continuity in only one direction.

2. Reconnect the ohmmeter leads to the negative terminal and the three stator terminals one at a time.

Reverse lead; Ohmmeter should only show unidirectional conduction.

3. Connect the ohmmeter leads to the “D +” terminal and the three stator terminals one at a time.

Reverse leads and ohmmeters need to show conduction in only one direction. If the diode is found to be defective, replace the diode assembly.

Figure 3: Diode Assembly Test 55 Amp Alternator diode assembly is shown, but so on.

1. Place the ohmmeter on the smallest scale and connect the ohmmeter between the stator leads. The resistance between the leads should be 14 15 ohms for a 55 amp alternator and .09 10 ohms for a 65-90 amp alternator. If the resistance is incorrect, the stator windings are open or shorted. Must be replaced.

2. Place the ohmmeter on the X1000 scale. Connect an ohmmeter between the stator core and the stator reed. There should be no continuity. If there is continuity, the stator is grounded and needs to be replaced.

1. Place the ohmmeter on the lowest scale and connect the ohmmeter between the slip rings. The resistance should be 3 4-3.75 ohms for a 55 amp alternator and 2.83.1 ohms for a 65-90 amp alternator.

2. If the resistance is too low, there is a short circuit in the rotor, if the resistance is infinite, there is no continuity and the rotor has an open circuit and needs to be replaced.

3. Place the ohmmeter on the x1000 scale and reconnect the ohmmeter to either the slip ring or the rotor core. There should be no continuity. If there is continuity, the rotor is grounded and needs to be replaced.

4. Clean the slip ring with very fine sandpaper. Rings that are worn or perforated should be turned on on a lathe. If the slip ring cannot be repaired, the minimum ring diameter is 1 1/16 “26.8 mm. Replace the slip ring as outlined in step 5. 6.6.

5. Remove the rear bearing from the end of the rotor slip ring, unsolder the wire from the slip ring, bend the end of the rotor winding, pull out the slip ring and make sure the end of the rotor winding is undamaged To do.

6. Insert the end of the rotor winding into the slip ring and press the new slip ring against the rotor. The end of the slip ring should be 9/64 “3.5 mm from the end of the collar, solder the rotor windings to the slip ring terminals and retest by turning the ring on a lathe. The runout is 0012 “.03 mm.

bearing

Always replace the bearing. If the replacement front bearing is sealed on only one side, the open side must face the rotor. If the replacement rear bearing is sealed on only one side, the open side must face the other side of the rotor.

brush

If necessary, replace the brush longer than 6 mm, unsolder the brush from the voltage regulator, and solder a new brush to prevent the solder from hitting the strands of the brush leads.

The brush should be able to slide freely in the holder when the normal spring tension is 10-14.

Reassembly

1. Attach the bearings, retainers and screws to the front housing and press the rotor against the housing.

Press the bearing at the end of the rotor slip ring and solder the stator to the diode assembly. Be careful when soldering near diodes as they can be damaged by heat.

2. Attach the insulator to the stator assembly, assemble the stator assembly and rear housing, attach the wave washer or O-ring to the rear housing, align the scribe marks, and assemble the front housing and rear housing.

3. Install the keys, fan assembly, and spacers, install the pulleys, lock the washers and nuts, and tighten the nuts 23-29 feet 3-4 Nm. Make sure the rotor rotates freely and install the voltage regulator and capacitor.