Wednesday, April 6, 2011

Alternators

What is an Alternator?
An alternator is fitted to a motor vehicle to maintain the charge in the battery while the vehicle is in operation. engine runs on air, fuel and spark. The spark is the center of it all, and for that we need electricity. Your battery supplies electricity, but only enough to get you a few miles down the road. We need more. That's where the alternator comes in.The alternator continually charges the battery.



                                                                           Major components of charging system:
nBattery
nDrive belt
nWiring
nWarning light (charge indicator)
nAlternator
nVoltage regulator











Rotor winding to ground test:


Set the meter on 2K. Place the black lead on the centre of the rotor shaft indicated. Place the red lead on the slip ring as indicated.
There should be no circuit between the rotor shaft and the slip ring.
The meter should read infinity
If there is a circuit the rotor winding has shorted to ground and will need to be replaced. 





Spec
Meter reading
Pass / Fail
Infinite
Infinite
Pass




Rotor winding internal resistance test:
Set the Ohms meter on 200Ω, test for internal meter resistance by touching the two leads together. Internal resistance of the meter must be taken away from the actual reading.
Place one end of each lead on the slip rings as indicated to obtain reading. The reading specification is 2Ω to 6Ω. Internal resistance 0.3

Spec
Meter reading
Less Internal Meter Resistance
Actual
Pass / Fail
2 - 6 Ω
3.2
3.2-0.3
32.9
Pass


Resting Stator Winding resistance:
Set Ohms meter on 200
Ω, test for internal meter resistance by touching the two leads together. Internal resistance of the meter must be taken away from the actual reading. Select the common terminal of the stator winding terminals A to D. Connect the black lead to the common point. Connect the red lead to the other terminal one after the other and record their resistance they should all be approximately the same from 0.0Ω - .2Ω.

Testing stator winding to ground test:
Spec
Meter reading
Less Internal Meter Resistance
Actual
Pass/ Fail
0.0 Ω - .2Ω
0.3Ω
0.3Ω - 0.3
0
Pass
0.0 Ω - .2Ω
0.3Ω
0.3Ω - 0.3
0
Pass
0.0 Ω - .2Ω
0.3Ω
0.3Ω - 0.3
0
Pass


Set the meter on 2K. Place the red lead of the meter on the common stator winding terminal. the black lead of the meter on the body of Alternator as indicated E.(Second image from page 4)

Testing the rectifier positive diodes:
Set the meter on diode test mode. put the common lead on B terminal. Then touch the positive lead on each of the P terminals and record the reading.
Place the positive lead on B terminal. Then touch the common lead on each of the P  terminals and record the readings. The resistance should be high.

Results for positive diode testing with common lead on B
No
Spec 0.5 VD to 0.7 VD
Pass / Fail
1
.528 VD
Pass
2
.527 VD
Pass
3
.519 VD
Pass
4
.524 VD
Pass
Results for positive diode testing with positive lead on B
No
Spec Infinite
Pass / Fail
1
Infinite
Pass
2
Infinite
Pass
3
Infinite
Pass
4
Infinite
Pass


Testing the rectifier Negative diodes
Set the meter on diode test mode. Put the common lead on E terminal. Then touch the positive lead on each of the P terminals and record the readings. The resistance should be high. 
Place the positive lead on E terminal. Then touch the common lead on each of the P terminals and record the readings.

Results for positive diode testing with positive lead on B
No
Spec Infinite
Pass / Fail
1
Infinite
Pass
2
Infinite
Pass
3
Infinite
Pass
4
Infinite
Pass


Results for negative diode testing with positive lead on E
No
Spec 0.5 VD to 0.7 VD
Pass / Fail
1
.510
Pass
2
.527
Pass
3
.517
Pass
4
.520
Pass

Testing the voltage regulator
Locate the wiring diagram for regulator using following information on the regulator to identify the correct specifications. If the regulator number doesn't match any specified, use the most common set point voltage for the specification then wire to diagram test.

Regulator spec’s chart
Part Number
M15 12600-0610
3K 08
Yes / N/A
Field Setting
A
Checked
Yes /NA
Voltage
12
Checked
Yes /NA
Set Point Spec
14.6
Obtained
Yes /NA


Now you have checked all the settings, have attained the set point voltage spec and understand how to use the regulator tester, continue to record your findings.

Regulator results chart
Short Circuit Light
MUST BE OFF or turn off tester - OFF
Pass
Warning Light
Should come on and stay on - ON
Pass
Field Light
Should flash continuously - Flashy
Pass
Set Point voltage
Actual reading
14.6 – 14.7
Pass



Common charging system wiring diagram and symbols














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