Alternator off Car Testing

Dismantle:

1. Remove the nut on "B" terminal and insulator.

2. Remove the three nuts that hold the rear cover, remove the rear cover.

3. Remove the brush holder and voltage regulator.

4. Remove the four screws that hold the recifier, remove the rectifier.

5. Remove the four screws that hold the voltage regulator, remove the regulator.

6. Carry out test as scheduled on the following pages.
————————————————————————————————————————
Rotor winding to ground test:

Set the meter on 2K. Place the black lead on the centre of the rotor shaft as 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
Infinity   Infinity                 Pass
————————————————————————————————————————
Rotor winding internal resistance test:

Set the Ohms meter on 200Ω, test for internal meter resistance by touching the two leads together. Remember that the 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 in 2Ω to 6Ω
Spec          Meter reading          Less Internal Meter resistance          Actual          Pass/Fail
2~6Ohms   3.4Ω                       0.5Ω                                               2.9Ω            Pass
Too low that's means winding contact other winding—reduce resistance
Too high that's means insulation dirty not good connection between winding and rotor slip ring.
————————————————————————————————————————
Testing Stator Winding resistance:

Set Ohms meter on 200Ω，test for internal meter resistance by touching the two leads together. Remember that the internal resistance of the meter must be taken away from the actual reading. Select the common terminal ( the one with the most wires attached) of the stator winding terminals A to D. 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~0.2Ω

Testing stator winding to ground test:
Spec               Meter reading               Less Internal Meter Resistance               Actual               Pass/Fail
0.0~0.2Ω       0.5Ω                             0.4Ω                                                     0.1Ω                 Pass
0.0~0.2Ω       0.5Ω                             0.4Ω                                                     0.1Ω                 Pass
0.0~0.2Ω       0.5Ω                             0.4Ω                                                     0.1Ω                 Pass

Set the meter on 2K. Place the red lead of the meter on the common stator winding terminal (theterminal with most wires connected to it). and the Black lead of the meter on the body of Alternator as indicated by E.

There should be no circuit between the stator winding and ground. The meter should read infinity, if there is a circuit the stator has grounded and requires replacement.
Spec          Actual          Pass/Fail
Infinity        Infinity          Pass
————————————————————————————————————————
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.

The resistance should be low.

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 0.5VD to 0.7VD          Pass/Fail
1              0.515VD                              PASS
2              0.51VD                                PASS
3              0.51VD                                PASS
4              0.51VD                                PASS

Results for positive diode testing with positive lead on B
NO          Spec Infinity          Pass/Fail
1              Infinity                   PASS
2              Infinity                   PASS
3              Infinity                   PASS
4              Infinity                   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.

The resistance should be low

Results for negative diode testing with common lead on E
NO          Spec Infinity          Pass/Fail
1              Infinity                   PASS
2              Infinity                   PASS
3              Infinity                   PASS
4              Infinity                   PASS

Results for negative diode testing with positive lead on E
NO          Spec 0.5V to 0.7VD          Pass/Fail
1              0.542VD                           PASS
2              0.542VD                           PASS
3              0.527VD                           PASS
4              0.522VD                           PASS
————————————————————————————————————————
Features of the Transpo Voltage Regulator Tester:

1. 12,24 and 32 test voltages at 0.5 and 3 amperes field current.
2. Digital meter with accuracy to within + or -0.1 of a volt.
3. Short circuit lamp if this comes on it indicates a short circuit in wiring system.
4. Field circuit lamp ( small) to indicate regulator switching frequency.
5. Warning light circuit simulator.

Operating Instructions for Transpo regulator tester:

1. Set the voltage control to 12 volts
2. Set the field current switch to 0.5amps
3. Set the "FIELD" switch to "A" or "B" according to the information chart for the regulator
4. Connect the test leads according to the diagram for the regulator
5. Turn the power switch to the on position
6. If the short circuit lamp comes on it indicates a short circuit, quickly turn "OFF" the tester.
7. The field circuit lamp ( small LED) indicates regulator switching frequency, this lamp should flash rapidly
8. The warning light circuit simulator ( the large lamp) should come on and stay on.
9. The volts meter should indicate the set voltage according to the information chart for the regulator + or -1 volt.
————————————————————————————————————————
Testing the voltage regulator:

Procedure for testing the voltage regulator, now you have read the extracts from the Transpo regulator test manual on page7.

Locate the wiring diagram for the regulator using the following 3 pages and the numbers on the regulator to identify the correct specifications. If the regulator number dosen't match any specified, use the most common set point voltage for the specification then wire to diagram and test.

Regulator spec's chart

Part Number          M126000-0400  IN220/IN250          Yes/N/A

Field Setting           "A"          Checked                              YES

Voltage                   12          Checked                              YES

Set Point Spec       14.4        Checked                              YES

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

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 Lighte                  Should flash continuously                Flashing       PASS

Set Point voltage          Actual reading     14.4                                       PASS

————————————————————————————————————————

Checking the brush protrusion length:

It is  important to check length of the brushes as they supply electricity to the slip rings and if they are to short the brush spring can't apply enough pressure to maintain constant contact. This causes excess sparking that damages the slip rings and reduces the output of the alternator. Brushes are measured between (A) the slip ring contact face and (B) the face of the brush holder.

Brush No          Minimum length          Actual length          PASS/FAIL

1                       4.0mm                       5.5mm                   Pass

2                       4.0mm                       4.9mm                   Pass

Instructions for writing your report:

The rotor winding to ground test results was infinity, that's means from rotor shaft to slip ring,  the circuit was open circuit, if i got any reading on the meter that's means it was some problem on rotor winding. The rotor winding internal resistance test: the meter reading was 3.4Ω, the less internal meter resistance was 0.5Ω， theactual reading was 2.9Ω, if i got the result too low that means winding contact other winding, so the resistance was reduce, if I got the results too high that means insulation dirty not good connection between winding and rotor slip ring.

The results about the testing stator winding resistance: The meter reading were 0.5Ω, the less internal meter resistance were 0.4Ω, the actual reading were 0.1Ω. If I got low number which means the stator winding past test, if I got high result which means it not good connection between winding to the terminal, and the testing stator winding to ground test, the results was infinity, which means from stator winding terminal to the body of alternator, this circuit is open circuit.

The result about the rectifier positive diodes were 0.515VD, that means from B terminal to each P terminal were close circuit, when I tested positive diode testing with positive lead on B terminal, the result were infinity, because those were open circuit. When i tested negative diode testing with common lead on E, the result were infinity and the result about negative diode testing with positive lead on E were 0.524VD.

The testing the voltage regulator, my part number is IN220/IN250, I checked the field setting was "A", the voltage was 12V, the set poin Spec was 14.4, when I did the test, the short circuit light was off, warning light was on,field light was falshing and the actual reading was 14.4, so this testing was pass.

When I did the brush protrusion length,the brush 1's length was 5.5mm,so the test was pass,however the brush 2's length just over than 4.0mm, that need replace.