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Updated 05-19-2006

Alternator Swap
GM Wiring 


On the back of the alternator is the battery lead wire. Usually a red insulator but not always, and on the SIDE of the case is a place for a 2 wire plastic plug. The plug leads are parallel with the edge of the case. IF you find an alternator with the 2 wire spades IN LINE with the fan, this is the older style WITHOUT the internal regulator. Where this thing plugs in cast on the case below the opening for the plug should be a number 1 and 2 below the respective terminals.

Wire #1 goes to the key switch accessory terminal with a (10 ohm 10 watt) in line resister ((if you have an old style key switch that does not have an accessory terminal you will need the Radio Shack part number 276-1661 diode to put in line with the #1 wire. It is installed with the stripe towards the alternator. This will allow the car to stop when your key is turned off)), this wire is HOT with the key in the RUN position, BUT NOT THE START POSITION.

Wire #2 can be hooked directly to the + battery wire on the back of the case, but should be connected to the battery side of the starter solenoid if the wire run is from one side of the car to the other. (This is because if the alternator  output is high there will be a voltage drop of about 1 volt from the alternator to the battery starter solenoid terminal and the rest of the car components will not have the correct voltage during high charging rates). Wire #2 is a sense voltage source for the regulator.

The idiot light is rather unique. the light is a small dash lamp bulb on a special plug in base. NORMAL lights require a ground and a hot wire. THIS LIGHT IS NOT GROUNDED, instead both leads are insulated from the car body. One side goes to the key switch, where it is fed 12 volts when the key is ON, and the other goes to #1 on the alternator. With the key ON and the engine not running, the light lights up, as there is a voltage difference between the 2 leads. AS the engine is running this wire has 12 volts across its entire length and the lamp goes out, as BOTH LEADS have the same voltage, when the alternator is charging. If the alternator quits charging, then this wire loses its voltage and the light comes one says I AIN'T WORKING, so you know something is wrong. Usually on the GM's the battery wire off the back of the alternator goes to the battery side terminal of the starter solenoid. There is an in line fuse here most often on the originals, consisting of a fusible link. Ditto for the headlights and the rest of the cars wiring needs.

If you have an ammeter, make certain that the STARTER DRAW IS NOT PUT ACROSS THE TERMINALS OF THE AMMETER. The location of the ammeter can depend on what you want to know. There are 2 places to put it, which I won't get to here. A normal GM internal regulator alternator can have an output from 45-70 amps depending on several variables. By changing the internal windings and rotor it is possible to get 120-140 amps, but the life is shortened. You can also have a self excited alternator, by changing the regulator and then you have NO little wire plug to worry about, Just the big battery wire. Speaking of which, this battery wire MUST BE 10 gauge minimum and I like to solder the terminals on the end. I don't trust crimp connections. If you have to run this wire a long ways, then the wire MUST BE BIGGER. Delco manuals sometimes call for #1 wire sizes for some alternators and 3/0 for some starters, but you OUGHT TO SEE THE BATTERIES!!!

The following is a picture of the wiring for the new alternator with old style key and new style key with an example of the original wiring found in most Studebaker Hawks or Larks. You will need to check your wiring diagram to make sure the wiring is the same as that show in the picture below.

wire example

 


Mopar

I know most are going to recommend the one-wire GM setup but I prefer the Mopar unit. If you start with the standard Stude V8 bracket on the exhaust manifold the front lug of the Mopar alternator bolts to the front of the Stude bracket and positions the belt alignment perfectly (assuming you use a single groove pulley). A piece of angle iron with one hole drilled in it is welded to the Stude bracket to make the support for the rear lug of the alternator. The early Mopars ('61-'69) used the same voltage regulator as the alternator equipped Studies. It's a simple two wire hookup. The '70 and later used a solid state regulator with three wires. The regulator can be mounted in the same location as the original Stude and most of the original wires used.

Alternator Model 10SI  61 amp. from 1984 chevy or 1971 international truck

            
         DESCRIPTION  
        
The alternator illustrated in Figs. 1 and 2 features a solid state regulator that is mounted inside the alternator slip ring end frame. All regulator components are enclosed into a solid mold, and this unit along with the brush holder assembly is attached to the slip ring end frame. The regulator voltage setting never needs adjusting, and no provision for adjustment is made.

The alternator rotor bearings contain a supply of lubricant sufficiently adequate to eliminate the need for periodic lubrication. Two brushes carry current through the two slip rings to the field coil mounted on the rotor and under normal conditions will provide long periods of attention-free service.

The stator windings are assembled on the inside of a laminated core that forms part of the alternator frame. A rectifier bridge connected to the stator windings contains six diodes and electrically changes the stator A. C. voltages to a D. C. voltage which appears at the alternator output terminal. Alternator field current is supplied through a diode trio which also is connected to the stator windings. A capacitor, or condenser, mounted in the end frame protects the rectifier bridge and diode trio from high voltages and suppresses radio noise.

No periodic adjustments or maintenance of any kind are required on the entire alternator assembly.
alternator diagram 1

OPERATION

Updated 05-19-2006
A typical wiring diagram is illustrated in Fig. 3. The basic operating principles are explained as follows. To excite or start the alternator the switch is closed, current from the battery flows through the ammeter and resistor (10 ohm 10 watt)  to the alternator No. 1 terminal, through resistor R1, diode Dl, and the base emitter of transistor TR1 to ground, and then back to the battery. This turns on transistor TR1 and current flows through the alternator field coil and TR1 back to the battery.

With the alternator operating, A.C. voltages are generated in the stator windings, and the stator supplies D. C. field current through the diode trio, the field, TR1, and then through the grounded diodes in the rectifier bridge back to the stator. Also, the six diodes in the rectifier bridge change the stator A. C. voltages to a D. C. voltage which appears between ground and the alternator 'BAT' terminal. As alternator speed increases, current is provided for charging the energizer and operating electrical accessories. Also, with the alternator operating, the same voltage appears at the 'BAT' and No. 1 terminals, and the ammeter gauge goes out to indicate the alternator is producing a charge for the battery.

The No. 2 terminal on the alternator is always connected to the battery. but the discharge current is limited to a negligible value by the high resistances of R2 and R3. As the alternator speed and voltage increase, the voltage between R2 and R3 increases to the point where zener diode D2 conducts. Transistor TR2 then turns on and TR1 turns off. With TR1 off, the field current and system voltage decrease, and D2 then blocks current flow, causing TR1 to turn back on. The field current and system voltage increase, and this cycle then repeats many times per second to limit the alternator voltage to a preset value.

Capacitor Cl smooths out the voltage across R3, resistor R4 prevents excessive current through TR1 at high temperatures, and diode D3 prevents high induced voltages in the field windings when TR1 turns off. Resistor R2 is a thermistor, which causes the regulated voltage to vary with temperature, thus providing the optimum voltage for charging the battery.
alternator diagram 2

TROUBLESHOOTING

In order to locate and correct defects in the charging system in the shortest possible time, the following procedures should be used. Only a portion of these procedures need be performed. It will never be necessary to perform all the procedures in order to locate the trouble.

To avoid damage to the electrical equipment, always observe the following precautions:

Do not polarize the alternator.

Do not short across or ground any of the terminals in the charging circuit. Never operate the alternator with the output terminal open circuited.

Make sure the alternator and battery have the same ground polarity.

When connecting a charger or a booster battery to the vehicle battery, connect negative to negative and positive to positive.

Trouble in the charging system will show up as one or more of the following conditions:

An undercharged battery as evidenced by slow cranking and low specific gravity readings.

An overcharged battery, as evidenced by excessive water usage.

         Undercharged Battery
        
           This condition, as evidenced by slow cranking and low specific gravity readings, can be caused by one or more of the following conditions
        
1. Insure that the undercharged condition has not been caused by accessories having been left on for extended periods.
        
2. Check the drive belt for proper tens ton.
       
3. Inspect the wiring for defects. Check all connections for tightness and cleanliness, including the slip connectors at the alternator tor and firewall and the cable clamps and battery posts.
        
4. With ignition switch on and all wiring harness leads connected, connect a voltmeter from:
        
a. Alternator "BAT" terminal to ground.
        
b. Alternator No. 1 terminal to ground,
        
c. Alternator No. 2 terminal to ground.


A zero reading indicates an open between voltmeter connection and battery. Opens in the wiring harness connected between the No. 2 alternator terminal and battery may be be tween the terminals, at the crimp between the harness wire and terminal, or in the wire.
        
5. If previous Steps 1 through 4 check satisfactorily, check alternator as follows:
        
a. Disconnect battery ground cable.
        
b. Connect an ammeter in the circuit at the "BAT" terminal of the alternator,

c. Reconnect battery ground cable.
        
d. Turn on radio, windshield wipers, lights high beam and blower motor high speed. Connect a carbon pile across the battery.
        
e. Operate engine at moderate speed as re quired and adjust carbon pile as required to obtain maximum current output.
        
f. If ampere output is within 10 percent of rated output as stamped on alternator frame, alternator is not defective; re check Steps 1 through 5.
        
g. If ampere output is not within 10 percent of rated output, ground the field winding by inserting a screwdriver into the test hole, Fig. 4. NOTE: Tab is within 3/4" of casting surface. Do not force screw driver deeper than 1" into end frame.
fig4

h. Operate engine at moderate speed as required and adjust carbon pile as required to obtain maximum current output.
        
i. If output is within 10 percent of rated output, replace regulator and check field winding.
        
j. If output is not within 10 percent of rated output, check the field winding, diode trio, rectifier bridge and stator.
        
k. Remove ammeter from alternator and turn accessories off.
        
         Overcharged Battery
        
1. Connect a voltmeter from alternator No. 2 terminal to ground. If reading is zero, No. 2 lead circuit is open.
 
2. If battery and No. 2 lead circuit check good but an obvious overcharge condition exists, as evidenced by excessive battery water usage, proceed as follows:
        
a, Separate end frames. Check field winding for shorts. If shorted, replace rotor and regulator.
        
b. Connect ohmmeter using lowest range scale from brush lead clip to end frame as shown in Step 1, Fig. 5, then reverse lead connections.
        
c. If both readings are zero, either the brush lead clip is grounded or regulator is defective.

fig 5

d. A grounded brush lead clip can result from omission of insulating washer, Fig.5, omission of insulating sleeve over screw, or damaged insulating sleeve. Remove screw to inspect sleeve. If satisfactory, replace regulator.
        
        DISASSEMBLY
        
To disassemble the alternator, remove the four thru- bolts and separate the drive end frame and rotor assembly from the stator assembly by prying apart with a screwdriver at the stator slot. A scribe mark will help locate the parts in the same position during assembly. After disassembly place a piece of tape over the slip ring end frame bearing to prevent entry of dirt and other foreign material and also place a piece of tape over the shaft on the slip ring end. NOTE: Use pressure- sensitive tape and not friction tape, which would leave a gum my deposit on the shaft. If brushes are to be reused, clean with a soft, dry cloth.
        
To remove the drive end frame from the rotor, place the rotor in a vise and tighten only enough to permit removal of the shaft nut.
NOTE: Avoid excessive tightening, as this may cause distortion of the rotor. Remove the shaft nut, washer, pulley, fan, and the collar; and then separate the drive end frame from the rotor shaft.
        
         Rotor Field Winding Checks
        
To check for opens, connect the test lamp or ohmmeter to each slip ring. If the lamp fails to light or if the ohmmeter reading is high (infinite), the winding is open, Fig. 6.

fig 6

The winding is checked for short circuits or excessive resistance by connecting a battery and ammeter in series with the edges of the two slip rings. Note the ammeter reading and refer to specifications. An ammeter reading above the specified value indicates shorted windings; a reading below the specified value indicates excessive resistance. An alternate method is to check the resistance of the field by connecting an ohmmeter to the two slip rings, Fig. 6. If the resistance reading is below the specified value, the winding is shorted; if above the specified value, the winding has excessive resistance. The specified resistance value can be determined by dividing the voltage by the current. Remember that the winding resistance and ammeter readings will vary slightly with winding temperature changes. If the rotor is not defective but the alternator fails to supply rated output, the defect is in the diode trio, rectifier bridge or stator.
        
         Diode Trio Check
        
The diode trio is identified in Fig. 5. First connect an ohmmeter using lowest range scale from brush lead clip to end frame as shown in Step 2, Fig. 5; then reverse lead connections. If both readings are the same, check for grounded brush lead clip caused by omission of insulating washer, Fig. 5, omission of insulating sleeve over screw, or damaged insulating sleeve. Remove screw to inspect sleeve. if screw assembly is correct and both ohm-meter readings are the same, replace regulator.

To check the diode trio, remove it from the end frame assembly by detaching the three nuts, the attaching screw, and removing the stator assembly. Note that the insulating washer on the screw is assembled over the top of  the diode trio connector. Connect an ohmmeter having a 1-1/2 volt cell, and using the lowest range scale, to the single connector and to one of the three connectors, Fig. 7. Observe the reading. Then reverse the ohmmeter leads to the same two connectors. If both readings are the same, replace the diode trio. A good diode trio will give one high and one low reading. Repeat this same test between the single connector and each of the other two connectors.

fig 7

NOTE: Figs. 5 and 7 illustrate two diode trios differing in appearance. Either one of these diode trios may be used in these alternators, and the two are completely interchangeable.
       
         Rectifier Bridge Check
        
Note that the rectifier bridge has a grounded heat sink and an insulated heat sink connected to the output terminal. Also note the insulating washer located between the insulated heat sink and end frame, Fig. 8.

fig 8

To check the rectifier bridge, connect the ohmmeter to the grounded heat sink and one of  the three terminals, Fig. 8. Then reverse the lead connections to the grounded heat sink and same terminal. If both readings are the same, replace the rectifier bridge. A good rectifier bridge will give one high and one low reading. Repeat this same test between the grounded heat sink and the other two terminals and between the insulated heat sink and each of the three terminals. This makes a total of six checks with two readings taken for each check.
NOTE: If rectifier bridge is constructed as shown in Fig. 9, check with the rectifier bridge mounted in the end frame in the same manner as Fig. 8-- except connect ohmmeter pressing down very firmly onto flat metal connector and not onto threaded stud, Fig. 9.
        
The ohmmeter check of the rectifier bridge and of the diode trio is a valid and accurate check. Do not replace either unit unless at least one pair of readings is the same. CAUTION: Do not use high voltage to check these units, such as a 110-volt test lamp.

fig 9

Fig. 9 Rectifier Bridge Check
        
To replace the rectifier bridge, remove the attaching screw and the "BAT" terminal screw and disconnect the capacitor lead. Note the insulator between the insulated heat sink and end frame, Fig. 8. Rectifier bridges may vary in appearance but are completely interchangeable in these alternators.
        
         Stator Check
        
        
The stator windings may be checked with a 110-volt test lamp or an ohmmeter. If the lamp lights or if the meter reading is low when connected from any stator lead to the frame, the windings are grounded. If the lamp fails to light or if the meter reading is high when successively connected between each pair of stator leads, the windings are open, Fig. 10.
        
A short circuit in the stator windings is difficult to locate without laboratory test equipment, due to the low resistance of the windings. However, if all other electrical checks are normal and the alternator fails to supply rated output, shorted stator windings are indicated. Also, a shorted stator can cause the indicator lamp to be on with the engine at low speed.
        
        
         Brush Holder and Regulator Replacement
        
        
After removing the three attaching nuts, the stator and diode trio screw, Fig. 8, the brush holder and regulator may be replaced by removing the two remaining screws. Note the two insulators located over the top of the brush clips in Fig. 5 and that these two screws have special insulating sleeves over the screw body above the threads. The third mounting screw  may or may not have an insulating sleeve, if  not, this screw must not be interchanged with either one of the other two screws, as aground  may result causing no output or uncontrolled alternator output. Regulators may vary in appearance but are completely interchangeable in these alternators.

fig 10
       Fig. 10 Stator Windings Check
 
         Slip Ring Servicing
        
If the slip rings are dirty, they may be cleaned and finished with 400 grain or finer polishing cloth. Spin the rotor and hold the polishing cloth against the slip rings until they are clean. NOTE: The rotor must be rotated in order that the slip rings will be cleaned evenly. Cleaning the slip rings by hand without spinning the rotor may result in flat spots on the slip rings causing brush noise.
        
Slip rings which are rough or out of round should be trued in a lathe to . 002 inch maximum indicator reading. Remove only enough material to make the rings smooth and round. Finish with 400 grain or finer polishing cloth and blow away all dust.
        
         Bearing Removal and Lubrication
        
The bearing in the drive end frame can be removed by removing the retainer plate screws and then pressing the bearing from the end frame. If the bearing is in satisfactory condition, it may be reused, and it should be filled  one- quarter full with Delco- Remy lubricant No. 1948791 before reassembly. NOTE: Do not overfill, as this may cause the bearing to overheat. Use only 1948791 lubricant.
        
         Bearing Installation       

To install a new bearing, press in with a tube or collar that just fits over the outer race with the bearing and slinger assembled into the end frame as shown in Fig. 11. It is recommended that a new retainer plate be installed if the felt seal in the retainer plate is hardened or excessively worn. Fill the cavity between the retainer plate and bearing with 1948791 lubricant.

fig 11

Fig. 11  Drive End Bearing (Flat Washer
             May Be Used Instead of Slinger)
        
The bearing in the slip ring end frame should be replaced if its grease supply is exhausted. No attempt should be made to re lubricate and reuse the bearing. To remove the bearing from the slip ring end frame, press out with a tube or collar that just fits inside the end frame housing. Press from the outside of the housing towards the inside.      

To install a new bearing, place a flat plate over the bearing and press in from the outside towards the inside of the frame until the bearing is flush with the outside of the end frame. Support the inside of the frame with a hollow cylinder to prevent breakage of the end frame. Use extreme care to avoid misalignment or otherwise placing undue stress on the bearing.      

It is recommended that a new seal be installed whenever the bearing is replaced. Press the seal in with the lip of the seal toward the rotor when assembled--that is, away from the bearing. Lightly coat the seal lip with oil to facilitate assembly of the shaft into the bearing.
        
         REASSEMBLY
        
Reassembly is the reverse of disassembly. To install the slip ring end frame assembly to  the rotor and drive end frame assembly, remove the tape over the bearing and shaft and make sure the shaft is perfectly clean after removing the tape. Insert a pin through the holes to hold up the brushes. Carefully install the shaft into the slip ring end frame assembly to avoid damage to the seal. After tightening the thru-bolts, remove the brush retaining pin to allow the brushes to fall down onto the slip rings. When installing the pulley, the pulley nut must be torqued to 60 ft.lbs. If not properly tightened, it is possible that the nut and pulley could loosen and slip on the shaft.
      
To assist in tightening the pulley nut, a 5/16 inch hex hole is provided in the end of the shaft for holding with an Allen wrench. Also a special 15/16 inch socket wrench, Fig. 12, which is applicable to the nut is available from the Snap-On Tool Company. This special 1/2 inch drive socket wrench is designed with a cutout to receive the Allen wrench and may be used in conjunction with a torque indicating wrench. Where desired, a length of 3/8 inch pipe may be applied to the Allen wrench to provide additional leverage for the holding effort.
        
The special 15/16 inch socket wrench, Fig.12, is available from your local Snap-On representative under their number S-8183.

fig 12

Fig. 12 Torquing Pulley Nut
 
         Alternator Bench Check
       
To check the alternator in a test stand, proceed as follows:
        
        
1. Make connections as shown in Fig. 13, except leave the carbon pile disconnected. NOTE: Ground polarity of battery and alternator must be the same. Use a fully charged battery and a 10 ohm resistor rated at six watts or more between the alternator No. 1 terminal and the battery.
        
2. Slowly increase the alternator speed and observe the voltage.

3. If the voltage is uncontrolled with speed and increases above 15.5 volts on a 12-volt system or 31 volts on a 24-volt system, check for a grounded brush lead clip. If not grounded, replace the regulator and check field winding. NOTE: The battery must be fully charged when making this check.

fig 13

Fig. 13 Connections for Bench Check
        
        
4. If voltage is below 15. 5 volts on a 12-volt system, connect the carbon pile as shown.
      
5. Operate the alternator at moderate speed as required and adjust the carbon pile as required to obtain maximum current output.
        
        
6. If output is within 10 percent of rated output as stamped on alternator frame, alternator is good.
        
        
7. If output is not within 10 percent of rated output, keep energizer or battery loaded with carbon pile and ground alternator field, Fig. 13.
        
        
8. Operate alternator at moderate speed and adjust carbon pile as required to obtain maximum output.
        
        
9. If output is within 10 percent of rated output, replace regulator and check field winding.
        
        
10. If output is not within 10 percent of rated output, check the field winding, diode trio, rectifier bridge and stator as previously covered.