Isuzu KB P190. Manual — part 539

6D3-8 STARTING AND CHARGING SYSTEM

General On-Vehicle Inspection

The operating condition of charging system is indicated by the
charge warning lamp. The warning lamp comes on when the
starter switch is turned to "ON" position. The charging system
operates normally if the lamp goes off when the engine starts.
If the warning lamp shows abnormality or if undercharged or
overcharged battery condition is suspected, perform diagnosis
by checking the charging system as follows:
1. Check visually the belt and wiring connector.

2. With the engine stopped, turn the stator switch to "ON"

position and observe the warning lamp.

If lamp does not come on:

Disconnect wiring connector from generator, and ground

the terminal "L" on connector side.

If lamp comes on:

Repair or replace the generator.

Generator

Removal

1. Disconnect battery ground cable.

2. Move drive belt tensioner to loose side using wrench then

remove drive belt.

3. Disconnect terminal "B" wiring connector and connector.

4. Remove generator assembly.

Generator Power and Circuit Diagram

Inspection

Legend

1 Load resistor, set parallel to battery
2 Battery
3 Voltmeter
4 Ammeter
5 Ignition Lock
6 Charge Telltale
7 Generator

1. Disconnect battery.

2. Close off connecting cable from alternator terminal "B+".

3. Set ammeter (measuring range 100A) in disconnected line.

4. Connect controllable load resistor to battery terminal.

5. Set resistor in front of connection to "O"; connect first to

battery, then to resistor.

6. Connect tachometer.

7.

Connect oscilloscope according to manufacturer's

instructions.

8. Connect battery.

9. Start engine and read off resulting current at various engine

speeds.

STARTING AND CHARGING SYSTEM 6D3-9

Generator Power

1. Adjust load resistor, if the required load currents are not

attained.

2. The shape of the voltage curves on oscilloscope curve

should be regular.

3. Test value: 5 to 7A.

4. If the required minimum current intensity is not attained, or

if the oscilloscope picture shows variations, the alternator

should be overhauled.

Regulated Voltage Circuit Diagram

Legend

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 Generator

Installation

1. Install generator assembly and bring generator assembly to

the position to be installed.

2. Install generator assembly and tighten to the specified

torque.

Torque:

Long bolt: 35 N

⋅⋅⋅⋅m (3.6 kgf⋅⋅⋅⋅m)

Short bolt: 20 N

⋅⋅⋅⋅m (2.0 kgf⋅⋅⋅⋅m)

3. Connect wiring harness connector.

4. Move drive belt tensioner to loose side using a wrench, then

install drive belt to normal position.

5. Reconnect battery ground cable.

6D3-10 STARTING AND CHARGING SYSTEM

The generator has four external connections; the "B+" lead to
battery positive, "L" lead to the warning lamp circuit(max. 2
watts), "S" lead to battery positive terminal for battery sensing
and an earth connection.

Explanation of type inscripiton

Example:KC-A--> 14V 50-90A.

K

= Code for Stator OD(126mm OD).

C

= Compact Generator.

A

= Ausland (countries other than Germany)

>

= Direction of rotation(clockwise).

14V = Generator Operating Voltage.
50A = Stabilised output at 25 C at 1800 RPM./13.5

Volts.

90A = Stabilised output at 25 C at 1800 RPM./13.5

Volts.

Generator Connetions.

B+ : Battery Main Connection (battery positive)
S

: Battery Sense Connection(battery positive)

L

: Waring lamp(via warning lamp to Ignition switch)

BATT.SENSE

REGULATOR ASSEMBLY

HYBR10

ALTERNATOR ASSEMBLY

12V BATT.

1GN.SW.

300a*

WARN.LAMP

1.2 WATT

L

S

8+

SUPPRESSOR
CAPACITOR
0.5

µf

NOTE: * RESISTOR IS RECOMMENDED TO

ENSURE THAT THE GENERATOR
REMAINS FUNCTIONAL IN CASE OF
WARNING LAMP FAILURE

STARTING AND CHARGING SYSTEM 6D3-11

Warning

Do not reverse S and L connections as this will destroy the
warning lamp circuit of the regulator.
Ensure good electrical contact beween generator earth and
battery negative,

Operation

With the Iginiton switch turnded "ON", current is supplied via
the warning lamp to the "L" terminal of the regulator. Base
current is fed to T15 causing it to turn on, current then flows
from B+ through the rotor winding via the regulator brushes
and the collector emitter junction of T15 to earth completing
the circuit. The current in the rotor causes a magnetic field
between adjacent poles to be created, this field is rotated and
cuts the windings of the stator at right angles inducing a
voltage into them.
As the speed is increased this induced voltage increases and
results in curent being rectified in the 3 phase diode bridge and
supplied as DC to the B+ output and hence to the battery.
When the voltage at the B+ terminal of the battery reaches
around 14.2 volts, this voltage is monitored by the "S" lead and
turns the regulator Hybrid base current to T15 OFF removing
rotor current, resulting in a decrease in output voltage to below
the regulating voltage, T15 base current turns ON and the
whole cycle is repeated very rapidly.
D38 protects T15 and the regulator against the back voltage
developed across the rotor winding when T15 turns OFF.
The new generated EP regulators incorporate current limiting
in the warning lamp circuit.

Backup Regulation

The EP regulator will limit the output voltage to a safe level
should either the main B+ cable or the battery sense wire
become decoupled, the output voltage will be slightly above the
normal setting(1-3 volts).

Start up phase

When the Iginition switch is turned on and the engine is not
running, the current to the rotor is reduced by switching it on
and off at a 50% duty cycle, the frequency is approximately 4
KHz and may be audible at times.
This is quite normal, once the engine is started normal
regulation commences.

Warning lamp failure

Should the warning lamp fail, the generator will self excite by
deriving a small current from the phase connecion allowing the
voltage to build up to regulating level.
Note: no filed current will flow when the engine is cranking.