Alternators made by Bosch are regular 3-stage, self-redressing type alternators. Bosch 75 through 55-amp alternators use3 negative 3 positive and diodes associated with stator windings to redress current, Bosch 90 and 80-amp alternators utilize 14 diodes. All alternators utilize 3 exciter diodes associated with stator windings, while the motor is running these diodes turn off the alternator marker light and supply capacity to the voltage controller, Bosch controllers are transistorized strong state and fundamental with alternator.

(1) Bosch alternator part numbers are gone before by the numbers 0 120 or starting with an AL lettering a number and completion with a X.

1. You can interface a voltmeter to the alternator "B+" terminal and ground, voltmeter ought to demonstrate battery voltage, if not check wiring among battery and alternator.

2. Turn start on and watch that alternator pointer light goes ahead, if light does not come on, check wiring between notice light and alternator, including marker globule.

1. Guarantee associations at battery, alternator, and starter are perfect and tight, guarantee alternator motor and body are appropriately grounded, guarantee alternator belt is tight and in great condition.

2. Interface ammeter adhering to maker's directions, associate voltmeter prompts battery terminals.

3. Begin motor and keep running at 3000 R.P.M. change carbon heap to acquire most extreme alternator yield, don't enable voltage to go underneath 12.6 volts.

4. Alternator yield should level with alternator appraised yield, short 16-20 amps, if perusing is 16-20 amps beneath alternator rating, supplant controller and retest, whenever yield is still excessively low, fix or supplant the alternator.

TESTING and REPAIR

Diode Assembly

1. Place ohmmeter scale on x100 scale associate ohmmeter leads crosswise over "B+" terminal and 3 stator terminals each one in turn, switch drives, ohmmeter ought to show congruity one way as it were.

2. Reconnect ohmmeter leads crosswise over negative and 3 stator terminals each one in turn.

Turn around leads; ohmmeter ought to demonstrate coherence one way as it were.

3. Interface ohmmeter leads crosswise over "D+" terminal and 3 stator terminals each one in turn.

Invert drives, ohmmeter ought to show progression one way just, if diodes are observed to be blemished, supplant the diode get together.

Fig. 3: Diode Assembly Test Diode gathering for 55 amp alternator is appeared, others are comparable.

1. Spot ohmmeter on most minimal scale, interface ohmmeter crosswise over stator drives, opposition between leads ought to be 14 15 ohms for 55-amp alternator and .09 10 ohms for 65 through 90 amp alternators, if obstruction is off base, stator has open or shorted windings and must be supplanted.

2. Spot ohmmeter on X 1000 scale. Associate ohmmeter between stator center and stator lead, no progression should exist, if congruity exists, stator is grounded and should be supplanted.

1. Spot ohmmeter on most reduced scale, associate ohmmeter crosswise over slip rings, opposition ought to be 3 4-3.75 ohms for 55 amp alternator and 2.8 3.1 ohms for 65 through 90 amp alternators.

2. On the off chance that obstruction is excessively low, rotor has short out and it must be supplanted if opposition is endlessness no congruity, rotor has open circuit and should be supplanted.

3. Spot ohmmeter on x1000 scale, reconnect ohmmeter between either the slip ring and rotor center, no congruity should exist, if coherence exists, rotor is grounded and should be supplanted.

4. Clean slip rings utilizing a fine sandpaper, rings which are worn or set ought to be turned on machine, least ring distance across is 1/16" 26.8 m.m. in the event that slip rings are unrecoverable, supplant slip rings as delineated in stages 5 and 6.

5. Expel back bearing from slip ring end of rotor, unsolder wires from slip rings and twist up finishes of rotor twisting, pull off slip rings, guarantee closures of rotor winding are not harmed.

6. Supplement the closures of rotor twisting into slip ring and press new slip ring onto rotor, slip ring end must be 9/64" 3.5 m.m. from end of the neckline, patch rotor twisting to slip ring terminals, turn rings on machine and retest rotor, most extreme slip ring run out is 0012".03 m.m..

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