Alternator & Regulator Chevrolet Camaro II

DESCRIPTION

All General Motors vehicles, except Chevette and 1000 Diesel, use the Delcotron alternators, available with different idle outputs and maximum outputs of 42 (10SI), 56 (12SI), 63 (10SI), 66 (12SI), 70 (15SI), 78 (12SI), 85 (15SI) and 100 (27SI) amps.

View of Delcotron 10 SI Alternator with Integral Regulator. Scheme 1

All models feature a solid state regulator mounted inside the alternator, providing electrical system protection, eliminating needless wiring, saving space and preventing misconnection of terminals.

The construction and operation of all models is basically the same. Delcotron alternators consist primarily of 2 end frame assemblies, rotor, stator, brushes, slip rings and diodes. The rotor is supported in the drive end frame by ball bearings and in the slip ring end frame by roller bearings. Bearings are sealed and do not require periodic lubrication.

OPERATION

Two brushes carry current through the slip rings to the field coil mounted on the rotor. 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 6 diodes (three positive and three negative) molded into an assembly. This rectifier bridge changes stator A.C. voltage into D.C. voltage, which appears at the output "BAT" terminal.

Blocking action of the diodes prevents battery discharge back through the alternator. Because of this blocking action, need for a cutout relay is eliminated. Alternator field current is supplied through a diode trio, which is also connected to the stator windings. A capacitor is mounted in the end frame and protects the rectifier bridge and diodes from high voltage and suppresses radio noise.

Cutaway View of 100-Amp Heavy-Duty Alternator w/ Integral Regulator. Scheme 2

ADJUSTMENTS

No periodic adjustment or maintenance is required on alternator assembly. Regulator voltage is preset and no adjustment is provided, except on 100-amp heavy-duty alternators used by Cadillac.

Note. Adjustment of 100-amp alternators is accomplished by repositioning an external voltage adjustment cap in the slip ring end frame. For instructions, see Undercharged Battery, Heavy-Duty Alternator.

TROUBLE SHOOTING

Note. See the TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

ON-VEHICLE TESTS

Note. Before making electrical checks, visually inspect all terminals for clean and tight connections. Check alternator mounting bolts and drive belt tension. DO NOT ground No. 2 lead wire. Battery must be in good condition to test charging system.

Scheme 3

Scheme 4

Scheme 5

1. With ignition switch in "ON" position, connect a voltmeter from alternator "BAT" terminal to ground. (Scheme 3) Then connect voltmeter from No. 1 terminal to ground and then No. 2 terminal to ground. A zero reading indicates an open between connection and battery.
2. Alternators have a built-in feature, that avoids overcharging or accessory damage by preventing alternator from turning on if there is an open in wiring harness connected to No. 2 alternator terminal.
3. Opens in wiring harness connected between No. 2 terminal and battery may be between terminals, at crimp between harness wire and terminal, or in the wire. If test results are satisfactory, proceed to step 3. (Scheme 3): Delcotron Terminal Location ID (10 SI Alternator Shown)
4. Disconnect battery ground cable. Connect an ammeter in series with "BAT" terminal of alternator and disconnected "BAT" lead. (Scheme 4) Reconnect battery ground cable. Turn all available accessories on. (Scheme 4): Alternator Connections for Bench Testing & On-Vehicle Check of Undercharged Battery For standard alternator only.
5. Connect a carbon pile across battery. Operate engine at moderate speed (2000 RPM) and adjust carbon pile as necessary to obtain maximum current output.
6. If ampere output is within 10 amps of rated output stamped on alternator case, alternator is good. If output is not within 10 amps of rated output, ground field winding tab by inserting a screwdriver into end frame test hole. (Scheme 5) (Scheme 5): View Showing Field Ground Tab Accessible Through Hole in End Frame CAUTION: Tab is within 3/4" of casting surface. DO NOT force screwdriver deeper than 1" into end frame.
7. Operate engine at moderate speed (2000 RPM) and again adjust carbon pile as required to obtain maximum current output. If output is now within 10 amps, check field winding and test voltage regulator. If not within 10 amps of rated output, check field winding, diode trio, rectifier bridge and stator.

Note. If test hole is not accessible, disassemble alternator and test components.

Identification of Delcotron Terminal Locations For 27SI heavy-duty alternator only. Scheme 6

Heavy-Duty Alternator

1. Connect a voltmeter from "BAT" terminal on integral charging system to ground. (Scheme 6) A zero reading indicates an open between voltmeter connection and battery. If fault is not due to an open, disconnect positive battery cable.
2. Install knife blade switch between battery positive post and battery cable terminal. Connect Tester (AT-20) by setting ground polarity switch to negative position. Set load control to direct position. Connect "BAT" lead of ammeter to knife blade switch terminal stud and "REG" lead to positive battery cable on knife blade switch. Connect ammeter "GND" terminal to negative battery terminal.
3. On air conditioned vehicles, disconnect wire (18T) from blower motor. Close knife blade switch and start engine. Turn all accessories off and close vehicle doors. NOTE: Specifications are critical and given values must be adhered to.
4. Open knife blade switch and raise engine speed to 750 RPM. Voltage should not be allowed to rise above 16-volts. Adjust load control for highest ammeter reading. Reading should be 85.5-104.5 amps. NOTE: DO NOT let engine speed rise above 750 RPM, as alternator is capable of producing 145-150 amps which would destroy the ammeter.
5. If reading is 85.5-104.5 amps, generator is functioning normally. Adjusting voltage setting may correct undercharged condition. To adjust, remove voltage adjustment cap from slip ring end frame and turn it 90° and reinsert cap in connector body.

Voltage Adjustment Cap for 100-Amp Heavy-Duty Alternator. Scheme 7

Note. Cap is marked on 4 edges "LO", "2", "3", and "HI" positions. After adjusting cap position, check battery condition a week later to see if undercharged condition still exists. If so, reposition cap to next higher position and recheck in another week. (Scheme 7)

OVERCHARGED BATTERY

Note. Remember, an overheated battery will be overcharged even though charging circuit defects are not present.

Standard Alternators

If an obvious overcharge condition exists, as evident by excessive overflow of electrolite from the battery, disassemble alternator and test field coils, rotor and regulator.

1. Connect a voltmeter between integral charging system "BAT" terminal and ground. Turn off all accessories, increase engine speed as required to obtain maximum voltage reading. If voltage exceeds 15-volts, remove alternator and overhaul.
2. If voltage does not exceed 15 volts, adjust voltage to a lower value, by removing adjusting cap and rotating it to next lowest value. Reinsert cap into end frame. Check battery in a week and reset adjusting cap to next lower value, if still overcharged. (Scheme 7)

Bench Testing Rotor for Grounds and Opens. Scheme 8

1. Check rotor for grounds using an ohmmeter set at the x1000 scale. (Scheme 8) Connect ohmmeter leads to rotor shaft and, in turn, to each slip ring. Resistance should be very high (infinity). If resistance is not infinity, replace rotor assembly.
2. Test rotor for an open using an ohmmeter set to the x1 scale. Connect ohmmeter leads to each slip ring (Scheme 8) Resistance reading should be 2.4-3.5 ohms. If resistance is not as specified, replace rotor assembly.

Bench Testing Stator for Grounds Also test opens on 10 SI and 12 SI alternators. Scheme 9

Check stator for grounds using an ohmmeter set to x1000 scale. Connect ohmmeter leads to stator frame and any stator lead. (Scheme 9) Resistance reading should be infinity. If resistance is low, stator is grounded and must be replaced.

STATOR OPENS

Note. Delta windings of 15 SI and 27 SI series alternators cannot be checked for open circuits. However, if all other electrical checks are normal and generator fails to supply rated output, but will supply at least 10 amps, windings are probably defective.

Check 10 SI and 12 SI stator for open condition using an ohmmeter set to x1000 scale. Attach ohmmeter leads to any two stator leads, checking each pair of stator leads in succession. (Scheme 9) If either ohmmeter reading is high (infinity), windings are open. Replace stator assembly.

Bench Testing Typical Diode Trio. Scheme 10

1. Remove diode trio from end frame assembly. Connect an ohmmeter to single connector and to any of 3 stator lead connectors. Then reverse ohmmeter probes. (Scheme 10) A good diode will give one high and one low reading. If both readings are the same, replace diode trio. NOTE: Before replacing diode trio, also check rectifier bridge.
2. Repeat test, touching leads in turn from single connector to each of the 3 stator lead connectors. If any reading is zero, a short is indicated between diodes. Replace diode trio.

Bench Testing Rectifier Bridge & ID of End Frame Components. Scheme 11

1. Connect one ohmmeter lead to grounded heat sink. Connect other ohmmeter lead firmly against flat metal portion of terminal (not threaded stud). (Scheme 11) Then reverse leads to same heat sink and terminal. If both readings are the same, replace rectifier bridge.
2. A good rectifier bridge will give one high and one low reading. Repeat this same test between grounded heat sink and other 2 flat metal connectors. Then repeat same tests, this time between insulated heat sink and each of the 3 flat metal portions of connectors.
3. Check other bridge rectifiers in same manner. DO NOT replace rectifier bridge or diode trio unless at least one pair of readings is the same.

Test Equipment Hookup for Voltage Regulator Check For standard alternators only. Scheme 12

Standard Alternator

1. Remove voltage regulator from rectifier end shield. Connect a 12-volt battery, a voltmeter, a fast charger and a test light to the voltage regulator (Scheme 12) Test light should be on.
2. Turn ignition switch "ON" and slowly increase charging rate on fast charger. The vehicle generator light should dim at the voltage regulator setting.
3. Voltage regulator setting should be a minimum of 13.5-volts and a maximum of 16.0-volts. If voltmeter, vehicle generator light or test light do not operate as described, replace voltage regulator.

Note. As regulator is fully enclosed, there is no practical test of this unit.

Bench Testing Voltage Adjustment Cap For heavy-duty alternator only. Scheme 13

1. If none of the previous tests shows any defects and an overcharged condition was present, remove voltage adjustment cap (connector body) from slip ring end frame. Using an ohmmeter with middle range scale, attach leads to each pair of adjacent terminals (4 checks in all). (Scheme 13)
2. If any check is infinite, replace adjustment cap. There is no need to make this test for an undercharged condition.

Disassembly

1. Scribe an alignment mark on both end frames for reassembly reference. Remove 4 through bolts and separate drive end frame and rotor from rectifier end frame and stator. (Scheme 15) Remove and clean brushes to prevent grease from soaking into brushes.
2. Remove brush springs and place pressure sensitive tape (not friction tape) over rectifier end bearing and bearing shaft on rotor. Remove 3 nuts holding stator leads to rectifier bridge and remove stator.
3. Remove 1 screw with plastic insulator, holding diode trio to brush holder. Remove diode trio. Remove screws securing regulator and brush holder. Remove indicator lamp resistor, brush holder and regulator.
4. Remove rectifier bridge by removing screw with washer, screw at capacitor lead, and nut and washer from "BAT" terminal stud. Remove insulator and "BAT" terminal stud. Remove screw securing capacitor to end frame. To remove rotor from drive end frame, install rotor in vise, but only tight enough to remove shaft nut, washer, pulley, fan and collar. Separate end frame from rotor.

Scheme 14

1. To remove bearing in drive frame end, detach retainer plate screws and press bearing from frame. If bearing is in good condition, it can be reused. To install bearing, press in with a tube or collar that just fits over outer race. Install new retainer plate if felt seal is hardened or excessively worn. NOTE: All alternators use sealed bearings and no lubrication is needed.
2. Replace bearing in rectifier end frame if bearing is damaged. DO NOT attempt to relubricate or reuse bearing. Press bearing from outside of housing toward the inside, using a tube or collar just fitting inside end frame housing. (Scheme 14): Drive End Frame Bearing Assembly for Delcotron Alternators
3. To install a new bearing, place a flat plate over bearing and press in from outside toward inside until bearing is flush with outside of end frame. Support underside of end frame with hollow cylinder while pressing in bearing.
4. Always install a new seal whenever a bearing is replaced. Press seal in with lip of seal toward rotor, away from bearing. Coat seal lip lightly with oil to aid in later assembly.

Inspection

Wash all metal parts except bearings, stator and rotor. Inspect rotor slip rings, and clean with 400 grit or finer polishing cloth. Hold cloth against slip rings and spin rotor to clean evenly and avoid flat spots. Slip rings may be lathe turned to a .002" (.05 mm) indicator reading. Slip rings are not replaceable. Excessive damage will require rotor replacement. Inspect brushes for wear. Clean with acetone if necessary, and replace if excessively worn.

Exploded View of 10 SI Alternator. Scheme 15

Reassembly

1. Position "BAT" terminal stud in end frame with molded plastic insulator outside and fiber insulator inside. Place rectifier bridge in end frame and secure with nut and washer at one end and screw and washer at other. Install capacitor to end frame and heat sink.
2. Position regulator in rectifier end frame. Install indicator lamp resistor and brush holder over regulator and install screws securing regulator. Place diode trio on rectifier bridge and attach to regulator with insulated screw.
3. Place stator on end frame, with leads over rectifier bridge studs. Secure with nuts. Install brush springs and brushes in holder. Insert straight wire or pin through hole in end frame and holes in bottom of brush holder. NOTE: This will hold brushes in place until rotor is assembled into frame.
4. Install rotor in vise with drive end up. DO NOT overtighten vise. Install end frame, fan, pulley and washer over rotor shaft and secure with nut. Tighten nut to 40-60 ft. lbs. (54-81 N.m). Install rotor to rectifier end frame, aligning scribe marks. Remove wire holding brush. Install 4 through bolts through end frames and tighten.

Scheme 16

1. Remove cover plate from slip ring end frame. Hold rotor shaft with Allen wrench and remove shaft nut. Remove washer, pulley, fan and slinger. Remove 4 through bolts and separate rectifier end frame and stator from drive end frame and rotor.
2. Separate stator from rectifier end frame, removing 3 stator leads from studs. Remove and clean brushes in acetone if necessary. Place tape over bearing and shaft to protect from dirt. DO NOT use friction tape.
3. Remove 2 remaining nuts and washers from each rectifier bridge. Remove nut, lock washer, flat washer, insulating washer, and insulating collar from A.C. terminal studs.
4. Remove screw with flat washer and insulator from diode trio brush holder and remove diode trio, A.C. leads and inner insulator. Remove connector strap from each rectifier bridge. (Scheme 16) (Scheme 16): Components of Rectifier End Frame For 100-Amp heavy-duty alternator only.
5. Remove 2 nuts with internal tooth lock washers and flat washers, attaching bottom rectifier bridge. Remove 2 terminal studs. Remove screw with lock and flat washers, attaching rectifier bridge to end frame. Remove bridge.
6. Remove rectifier bridge nearest voltage adjuster, by removing 2 screws with lock and flat washers. To remove remaining bridge, loosen nut at "BAT" terminal. Remove screw with external tooth lock washer, securing "BAT" terminal lead to bridge. Remove additional screw securing bridge to end frame and remove bridge.
7. Remove 2 remaining screws holding brush holder. Make note of cap position, and remove voltage adjustment cap. Remove screw securing voltage regulator bracket to end frame and remove bracket and regulator.
8. Remove capacitor and "R" terminal lead. Remove rotor from drive end frame, by removing 4 screws from drive end bearing. Tap rotor out of housing with soft-faced hammer. Remove bearings.

Wash all metal parts except bearings, stator and rotor. Inspect rotor slip rings, and clean with 400 grit or finer polishing cloth. Slip rings may be lathe turned to a .002" (.05 mm) indicator reading. Slip rings are not replaceable. Excessive damage will require rotor replacement. Inspect brushes for wear. If excessively worn, replace.

1. Install capacitor and "R" terminal lead if removed. Position voltage regulator and adjuster to end frame. Place bracket over adjuster and secure with screw and external tooth lock washer.
2. Install voltage adjustment cap in same position as removed. One of the 3 rectifier bridges has an insulating sleeve at one end; other 2 are identical. Install one of identical bridges under "BAT" lead, securing to end frame with screw, lock and flat washers. Attach "BAT" lead to bridge with screw and external tooth lock washer.
3. Tighten "BAT" terminal nut. Install bridge with insulator at opposite side of end frame. Secure, using 2 screws with lock and flat washers. Place remaining bridge in end frame. Install 2 terminal bolts with internal tooth lock washers. Use flat washer at end with insulated bridge and capacitor lead at opposite end. Install, but do not tighten nuts.
4. Install screw with lock and flat washers, securing bridge to end frame and tighten screw. Tighten 2 nuts just installed. Install connector strap to each bridge. Install insulator at inside of end frame for A.C. terminal studs, and position diode trio and A.C. terminal leads. (Scheme 16)
5. Install insulating sleeve, insulating washer, flat and lock washers and nut to each A.C. terminal. Position diode trio and A.C. leads at each bridge, securing with nut and flat washer. Install brush holder over voltage regulator and fasten with 3 screws. Two screws nearest bearing have insulating and flat washers; other screw, a flat washer only.
6. Install brush springs and brushes. Hold brushes in position with wire through holder and end frame. Position stator leads to bridges at remaining open terminals. Secure with nuts and flat washers.
7. Install drive end frame, if removed. Align weld nut plate and secure with 4 screws. Remove tape from slip ring bearing and rotor shaft. Clean shaft. Install rotor and drive end frame to stator and slip ring end frame, aligning mounting lugs and through bolt holes. Install through bolts.
8. Remove wire holding brush and install cover plate to slip ring end frame. Secure with 4 screws. Assemble slinger, fan, pulley, washer, and nut on rotor shaft. Hold shaft with Allen Wrench and tighten nut to 75 ft. lbs. (102 N.m).

DELCO-REMY "DELCOTRON" ALTERNATOR TEST SPECIFICATIONS (1)

See also:
• TROUBLE SHOOTING - BASIC PROCEDURES