Bosch Alternator, Check
Check is composed of power check and regulated voltage check, carry out the regulated voltage check first. For simultaneous evaluation of electronic components, use appropriate oscilloscope curve.
The check can be carried out in assembled condition as well as on the test stand. The check here described is for vehicles in assembled condition, which can be applied analogously to the test stand.
A charged battery is required for this check.
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Note the following safety measures:
1. Negative terminal of battery, alternator and regulator must match.
2. Never allow the alternator to run on an uncontrolled open circuit.
3. Never short the terminals to alternator and regulator.
4. Do not reverse polarity of alternator.
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Alternator power.
Circuit diagram:
1 Load resistor, set parallel to battery
2 Battery
3 Voltmeter
4 Ammeter
5 Ignition lock
6 Charge telltale
| 7 Alternator | |||
|---|---|---|---|
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Close off connectin
g cable from alternator terminal B +
Set ammeter (measuring range 100 A) in closed line.
Connect controllable load resistor to battery terminal.
Set resistor in front of connection to 0; connect first to battery then to resistor.
Connect tachometer.
| Start engine and read off resulting current at various engine speeds. | |||
|---|---|---|---|
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Alternator power:
Adjust load resistor, if the required load currents are not attained.
The shape of the voltage curves on oscilloscope should be regular.
Test value, 5 to 7 A.
| If the required minimum current intensity is not attained, or if the oscilloscope picture shows variations, the alternator should be overhauled. | |||
|---|---|---|---|
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Regulated voltage.
Circuit Diagram:
1 Battery
2 Ignition lock
3 Charge telltale
4 Resistor, for attainment of load current with the battery set in series
5 Voltmeter
6 Ammeter
| 7 Alternator | |||
|---|---|---|---|
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Regulated voltage:
Connect tachometer, voltmeter, ammeter and load resistor according to manufacturer's instructions.
Remove cable from alternator terminal B+.
Set ammeter (measuring range 100 A) between disconnected cable and alternator terminal B+.
Set resistor in series to battery.
Start engine.
Adjust load resistor, until ammeter shows the prescribed value.
Read off regulated voltage - test value, see 'Technical Data'.
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Only check alternator with parallel switching, charged battery; switch off load resistor and battery after alternator standstill.
Disconnection of load without parallel switching battery leads to voltage transients, which can lead to damage to the alternator diodes.