June 18, 2024
Automotive 105


Alternators & Regulators Bosch with internal regulators
Alternators manufactured by Bosch are regular 3-period, self-rectifying variety alternators.

Bosch 75 via 55-amp alternators use3 damaging 3 good and diodes linked to stator windings to rectify existing, Bosch 90 and 80-amp alternators use 14 diodes.

All alternators use 3 exciter diodes connected to stator windings, when the motor is managing these diodes flip off the alternator indicator gentle and offer electrical power to the voltage regulator, Bosch regulators are transistorized sound point out and integral with alternator.

Model Volts/Amps

(1) Manufacturer’s Portion No.

190E 14/70 489 928
190D 14/70 489 897

All Some others 14/70 N/A
(1) Bosch alternator aspect numbers are preceded by the quantities 120 or commencing with an AL lettering a range and ending with an X.

1. You can link a voltmeter to the alternator “B+” terminal and floor, voltmeter should point out battery voltage, if not check wiring amongst battery and alternator.

2. Transform ignition on and check out that alternator indicator light will come on, if gentle does not come on, verify wiring involving warning light-weight and alternator, which includes indicator bulb.

1. Make sure connections at battery, alternator, and starter are clean and restricted, make certain alternator motor and system are effectively grounded, be certain alternator belt is tight and in great issue.

2. Hook up ammeter subsequent manufacturer’s recommendations, join voltmeter prospects to battery terminals.

3. Start off engine and run at 3000 R.P.M. modify carbon pile to receive maximum alternator output, do not enable voltage to go below 12.6 volts.

4. Alternator output need to equivalent alternator rated output, minus 16-20 amps, if examining is 16-20 amps under alternator ranking, exchange regulator and retest, if output is however much too small, restore or switch the alternator.

REGULATOR Handle VOLTAGE Examination

1. Link ammeter pursuing manufacturer’s guidelines, hook up voltmeter prospects to battery terminals, operate motor at 3000 R.P.M.

2. Operate motor right until voltage stops growing, voltage really should be 13.5-14.5 volts, if looking through is incorrect, eliminate regulator and guarantee brushes are for a longer period than 6 m.m..

3. If brushes are okay and regulator fails to keep voltage inside of specified limits, swap regulator and retest, if voltage is nonetheless incorrect, maintenance or replace alternator.


1. Clear away nut, lock washer, and pulley, keep in mind place of spacers, Then take out fan assembly and important, scribe mark on front and rear housings, take out voltage regulator and clear away screws, individual entrance and rear housings.

2. Disconnect capacitor from terminal eliminate nut, insulators, screws and washers.

Eliminate stator assembly.
3. Unsolder stator from diode assembly take away bearing wave washer or o ring from rear of housing.

3. Aid entrance housing and thoroughly press out rotor, do not enable rotor to fall, eliminate screws securing bearing retainer, take out retainer entrance bearing and seal take away rear bearing from slip ring at close of rotor.

Testing & Repair service
Diode Assembly
1. Area ohmmeter scale on x100 scale hook up ohmmeter prospects across “B+” terminal and 3 stator terminals a single at a time, reverse prospects, ohmmeter must suggest continuity in 1 direction only.

2. Reconnect ohmmeter qualified prospects throughout damaging and 3 stator terminals 1 at a time.

Reverse leads ohmmeter must point out continuity in one path only.

3. Hook up ohmmeter potential customers throughout “D+” terminal and 3 stator terminals one particular at a time.

Reverse sales opportunities, ohmmeter really should indicate continuity in one path only, if diodes are observed to be defective, substitute the diode assembly.

Fig. 3: Diode Assembly Test Diode assembly for 55 amp alternator is shown, other folks are identical.

1. Place ohmmeter on lowest scale, link ohmmeter across stator leads, resistance concerning sales opportunities should be 14 15 ohms for 55-amp alternator and .09 10 ohms for 65 as a result of 90 amp alternators, if resistance is incorrect, stator has open or shorted windings and will have to be replaced.

2. Location ohmmeter on X 1000 scale. Hook up ohmmeter concerning stator main and stator lead, no continuity need to exist, if continuity exists, stator is grounded and should be changed.

1. Area ohmmeter on least expensive scale, hook up ohmmeter throughout slip rings, resistance really should be 3 4-3.75 ohms for 55 amp alternator and 2.8 3.1 ohms for 65 by 90 amp alternators.

2. If resistance is much too reduced, rotor has short circuit and it will have to be replaced if resistance is infinity no continuity, rotor has open circuit and should be changed.
3. Position ohmmeter on x1000 scale, reconnect ohmmeter between both the slip ring and rotor core, no continuity need to exist, if continuity exists, rotor is grounded and should be replaced.

4. Clean slip rings employing a pretty fine sandpaper, rings which are worn or pitted ought to be turned on lathe, bare minimum ring diameter is 1 1/16″ 26.8 m.m. if slip rings are past fix, change slip rings as outlined in methods 5 and 6.
5. Eliminate rear bearing from slip ring close of rotor, unsolder wires from slip rings and bend up finishes of rotor winding, pull off slip rings, assure ends of rotor winding are not weakened.

6. Insert the finishes of rotor winding into slip ring and push new slip ring on to rotor, slip ring end ought to be 9/64″ 3.5 m.m. from finish of the collar, solder rotor winding to slip ring terminals, switch rings on lathe and retest rotor, maximum slip ring operate out is 0012″.03 m.m..

The Bearings
Generally change bearings, if substitution entrance bearing is sealed on one aspect only, open up aspect need to encounter rotor, if replacement rear bearing is sealed on a single side only, open side have to face away from rotor.

Assure brushes are for a longer period than 6 m.m. exchange if vital, unsolder brushes from voltage regulator, solder new brushes, and do not permit solder to operate into strands of brush leads.

Brush need to be no cost to slide in holder with typical spring rigidity of 10-14.

1. Install the bearing, retainer, and screws in front housing, press rotor onto housing.

Press bearing on slip ring end of the rotor, solder stator to diode assembly, physical exercise treatment when soldering around diodes because of to possible warmth damage.

2. Set up insulators on stator assembly, assemble stator assembly and rear housing, set up wave washer or O ring in rear housing, align the scribe marks and assemble entrance and rear housings.

3. Set up critical, supporter assembly, and spacers, put in the pulley, lock washer and nut, tighten nut to 23-29 ft. 3-4 Nm. Assure rotor spins freely, and put in voltage regulator and capacitor.