Alternator - Delco Buick Electra VI

DELCO-REMY SI SERIES ALTERNATORS

Delco-Remy Delcotron SI integral regulator series alternators are used on General Motors and some American Motor applications. The alternator used on individual models will be one of the following types: 10SI, 12SI, 15SI, 17SI, 27SI, CS-121 and CS-130. The 15SI, 17SI, and 27SI have delta stator windings and cannot be checked for opens. Other differences include current output and bearing stack up.

DELCO-REMY CS SERIES ALTERNATORS

CS models use a new type regulator. A diode trio is not used. A delta stator, rectifier bridge and rotor with slip rings and brushes are electrically similar to earlier models. A conventional pulley and fan is used on CS alternators. The CS-130 has an internal fan that cools the slip ring end frame, rectifier bridge and regulator.

Scheme 1

SI SERIES

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 3 positive and 3 negative diodes, molded into an assembly.

The rectifier bridge changes stator AC voltage into DC voltage at the output "BAT" terminal. Field current is supplied by a diode trio connected to the stator windings. A capacitor protects the rectifier bridge and diode trio from high voltages and suppresses radio noise.

CS SERIES

The CS alternator may be used with only 2 connections, battery positive and an "L" terminal to the charge indicator bulb. Use of "P", "F" and "S" terminals is optional. The "P" terminal is connected to the stator and may be connected externally to a tachometer. The "F" terminal is connected internally to field positive and may be used as a fault indicator. The "S" terminal may be connected externally to battery voltage to sense voltage to be controlled.

Regulator voltage setting varies with temperature and limits system voltage by controlling rotor field current. Regulator switches rotor field current on and off about 400 cycles per second. By varying on-off time, correct average field current for proper system voltage is obtained. At high speeds, the on-time may be 10 percent and the off time 90 percent. At low speeds, with high electrical loads, on-off time may be 90 and 10 percent respectively.

Delcotron alternators consist 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. All models feature an internally mounted solid state regulator. Delcotron alternators are available with rated outputs of 37-108 amps.

CS & SI SERIES

No periodic adjustment or maintenance is required on the alternator assembly. The regulator voltage is preset and no adjustment is provided.

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, tight connections. Check alternator mounting bolt torque and drive belt tension. DO NOT ground the No. 2 lead wire on SI series. Battery must be fully charged to test charging system.

Scheme 2

Scheme 3

Scheme 4

1. Place ignition switch in "ON" position. Connect voltmeter positive lead to alternator "BAT" terminal and negative lead to ground. (Scheme 2) Voltmeter should read battery voltage.
2. Connect voltmeter positive lead to terminal No. 1 and negative lead to ground. Repeat test with terminal No. 2. A zero voltage reading in step 1) or 2) indicates an open between voltmeter connection and battery. NOTE: Alternators have a built-in feature that avoids overcharging or accessory damage by de-activating the alternator if an open in the No. 2 alternator terminal circuit occurs.
3. An open circuit in the wiring harness connecting No. 2 terminal and battery may be between terminals. Check crimp between harness wire and terminal. Check for open in wire to battery. If test results are satisfactory, proceed to step 4). (Scheme 2): Identification of Delcotron SI Terminal Locations 10SI alternator is shown. Courtesy of General Motors Corp.
4. Disconnect battery ground cable. Connect an ammeter in series between "BAT" terminal of alternator and disconnected "BAT" lead. (Scheme 3) Reconnect battery ground cable and turn all accessories on.
5. Connect a carbon pile (or alternator tester) across battery. Operate engine at a speed of 2000 RPM and adjust carbon pile as necessary to obtain maximum current output. If ampere output is within 10 amps of rated output stamped on alternator case, alternator is okay.
6. If output was not within 10 amps of rated output, ground field winding tab by inserting a screwdriver into end frame test hole. (Scheme 4) If test hole is not accessible, disassemble alternator and test components.
7. Operate engine at 2000 RPM and adjust carbon pile as required to obtain maximum current output. If output is within 10 amps, check field windings, diode trio and voltage regulator. If output is not within 10 amps of rated output, check field windings, diode trio, rectifier bridge and stator.

Scheme 5

UNDERCHARGED BATTERY, CS SERIES

When operating normally the indicator light will come on when the ignition switch is placed in the "ON" position and go out when the engine starts. If the light operates abnormally, or if an undercharged or overcharged battery condition exists, the following procedure may be used to diagnose the charging system.

1. Visually check belt and wiring.
2. For vehicles without charge indicator light, proceed to step 5.
3. With ignition on and engine stopped, light should be on. If light is off, detach harness at alternator and ground terminal "L". If light comes on, replace or repair alternator. If light does not come on, locate open circuit between grounding lead and ignition switch. Check for burned out light.
4. With ignition on and engine running at moderate speed, light should be off. If light is not off, detach wiring harness at alternator. If light goes off, repair or replace alternator. If light stays on, check for grounded "L" terminal wire in harness.
5. If battery is undercharged or overcharged, detach wiring harness from alternator. With ignition on and engine not running. Connect voltmeter from ground to terminal "L". A zero voltmeter reading indicates an open circuit between terminal "L" and battery. Repair open circuit.
6. Reconnect harness to alternator and run engine at moderate speed. Measure voltage across battery. If voltage is more than 16 volts, repair or replace alternator. Turn on accessories or load battery with carbon pile to obtain maximum amperage. If output is within 15 amperes of rated output, alternator is okay. If output is not within 15 amperes of rated output, repair or replace alternator.

OVERCHARGED BATTERY ALL MODELS

An overcharged condition is indicated by excessive overflow of electrolyte from battery. Disassemble alternator and test field coils, rotor and regulator.

ALTERNATOR DIAGNOSTIC TESTER SI SERIES

Note. The Alternator Diagnostic Tester (J-26290) is designed as a quick check of alternator systems. It will detect about 98 percent of charging system faults.

1. Turn off engine, lights and accessories. Connect Alternator Diagnostic Tester (J-26290) to alternator. (Scheme 6) If tester light flashes, go to step 3). If tester light stays on, tester is at fault and should be replaced. If tester light is off, pull tester plug from alternator.
2. If tester plug is pulled from alternator and tester light flashes, rectifier bridge is faulty. If tester light stays off, check for 12 volts at terminal No. 2 of harness connector. Repair wiring or terminal if zero voltage is available. If voltage is available, tester is faulty.
3. Observe tester light with engine operating at fast idle (lights and accessories off). If tester light is off, charging system is okay. If tester light is on, remove alternator. Check diode trio, rectifier bridge and stator. If tester light is flashing, remove alternator and check voltage regulator, rotor field coil, brushes and slip rings.

Scheme 6

SI SERIES VOLTAGE REGULATOR

1. Connect a battery charger and voltmeter to battery. (Scheme 7) Turn ignition on and slowly increase rate of charge. Vehicle alternator light will dim at voltage regulator setting.
2. Voltage regulator setting should be a minimum of 13.5 volts and a maximum of 16 volts. If voltmeter or vehicle alternator light do not operate as described, replace voltage regulator.

Note. The voltage regulator test is valid, providing rotor field windings are okay. Regulator will test okay even though rectifier bridge or diode trio may be bad.

Scheme 7

Scheme 8

1. Set ohmmeter on x1000 scale. Check rotor windings for grounds. (Scheme 7) Connect one ohmmeter lead to rotor shaft and second lead to each slip ring. Resistance should be very high (infinity). If resistance is not as specified, replace rotor assembly.
2. Set ohmmeter on x1 scale and test rotor for opens. Connect an ohmmeter lead to each slip ring. (Scheme 8) Resistance reading should be 2.4-3.5 ohms. If resistance is not as specified, replace rotor assembly.

Stator Grounds

To check stator for grounds, set ohmmeter on x1000 scale. Connect one ohmmeter lead to stator frame and other lead to each stator lead. (Scheme 9) The resistance reading should be infinity. If resistance is not as specified, stator is grounded and must be replaced.

Stator Opens

Note. The delta windings of 15SI, 17SI and 27SI series alternators cannot be checked for open circuits. If all other electrical checks are normal and alternator fails to supply rated output, windings are probably defective.

To check for open conditions of 10SI and 12SI stators, set ohmmeter on x1000 scale. Attach ohmmeter leads to any 2 stator leads. Check each combination of stator leads in succession. (Scheme 9) If any ohmmeter reading is high (infinity), a winding is open. Replace stator assembly.

SI Series Diode Trio

1. Remove diode trio from end frame assembly. Connect one ohmmeter lead to brush connector and second lead to one of 3 stator lead connectors. Reverse ohmmeter probes. (Scheme 9) A good diode will give one high and one low reading. If readings are identical, replace diode trio.
2. Repeat test, touching leads in turn from single connector to each of 3 stator lead connectors. If any reading is zero, a short is indicated. Replace diode trio. Check rectifier bridge before replacing diode trio.

Scheme 9

Scheme 10

1. Connect one ohmmeter lead to grounded heat sink. Connect second ohmmeter lead firmly against flat metal portion of terminal (not threaded stud). (Scheme 10) Reverse leads to same heat sink and terminal. If readings are identical, replace rectifier bridge.
2. A good rectifier bridge will give one high and one low reading. Repeat test between grounded heat sink and 2 flat metal connectors. Test between insulated heat sink and each of its 3 flat metal connectors.
3. Check remaining bridge rectifiers in same manner. DO NOT replace rectifier bridge or diode trio unless one pair of readings are the same.

SI Voltage Regulator

1. Remove voltage regulator from rectifier end shield. Connect a voltmeter and battery charger to 12-volt battery with test light attached to voltage regulator. (Scheme 11) The test light should be on.
2. Turn charger on and slowly increase charge rate to 13.5-16 volts, test light will turn off. If test light does not turn off, replace voltage regulator.

Note. Voltage regulator operating specifications may vary due to temperature differences.

Scheme 11

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

1. Mount alternator on a test stand. Make connections as shown on charging system wiring diagram. (Scheme 5) Leave carbon pile disconnected. Ground polarity of alternator and battery must be the same. Battery must be fully charged. Use a 30-500 ohm resister between battery and terminal "L".
2. Slowly increase alternator speed and observe voltage. If voltage is uncontrolled and increases to above 16 volts. Rotor field is shorted, regulator is defective, or both conditions exist. A shorted rotor field coil can cause the regulator to become defective.
3. If voltage is lower than 16 volts, increase speed and adjust carbon pile to obtain maximum amperage output. If output is within 15 amperes of rated output, alternator is okay. If output is not within 15 amperes of rated output, replace alternator.

Scheme 13

Removal

1. Disconnect negative battery. CAUTION: Failure to observe this step may result in an injury from hot battery lead at generator.
2. Disconnect battery cable and harness connector at generator. Remove brace bolt and bolt at tensioner. Remove Through bolt and generator.

Installation

1. Install generator and Through bolt loosely. Reconnect battery cable and harness connector (pivot generator for access if necessary).
2. Install bolt at tensioner and tighten 20 ft.lbs. (27 N.m). Install rear brace bolt and tighten 20 ft.lbs. (27 N.m). Install Through bolt and tighten to 37 ft.lbs. (50 N.m). Reconnect negative battery cable.

1. Disconnect negative battery. CAUTION: Failure to observe this step may result in an injury from hot battery lead at generator.
2. Loosen top generator bracket to engine bolt. Remove upper generator bracket to engine bolt. Raise car. Remove right rear wheel. Remove splash guards.
3. Remove toe link rod outer end - swing up and left. Remove lower generator bracket to engine bolt. Remove generator adjusting bolt and belt. Remove upper generator to bracket bolt.
4. Disconnect generator wires. Rotate generator bracket lower end toward engine. Remove generator with shield.

1. Install generator with shield. Connect generator wires. Install generator to bracket bolt. Install generator adjusting bolt. Rotate generator and bracket up into position.
2. Install lower generator bracket to engine bolt. Lower car. Install upper generator bracket to engine bolts and tighten to 37 ft.lbs. (50 N.m). Install top generator bracket to engine bolt and tighten to 59 ft.lbs. (80 N.m). Raise car.
3. Install generator belt and generator adjusting bolt. Tighten adjusting belt to 20 ft.lbs. (27 N.m). Install toe link rod outer end ( DO NOT change adjustment). Install splash guards. Install right rear wheel.
4. Lower car. Install upper generator to bracket bolt and tighten to 37 ft.lbs. (50 N.m). Reconnect negative battery cable.

DISASSEMBLY (ALL MODELS)

1. Scribe alignment mark on both end frames for reassembly reference. Remove through bolts and separate drive end frame and rotor from rectifier end frame and stator. (Scheme 14) 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 nuts holding stator leads to rectifier bridge. Remove stator.
3. On SI series, remove one screw with plastic insulator. Hold diode trio to brush holder. Remove diode trio. Remove screws securing regulator and brush holder. Remove indicator light resistor, brush holder, and regulator.
4. Remove rectifier bridge by removing screw and washer. Remove screw at capacitor lead. Remove nut/washer from "BAT" terminal stud. Remove insulator and "BAT" terminal stud. Remove screw securing capacitor to end of frame.
5. Install rotor in vise just tight enough to remove shaft nut. Remove 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 place with a tube or collar that fits over outer race. Install a new retainer plate if felt seal is hardened or excessively worn. NOTE: All alternators use sealed bearings and no lubrication is required.
2. Replace bearing in rectifier end frame (if damaged). DO NOT attempt to lubricate or reuse bearing. Press bearing from outer housing toward center of unit. Use a tube or collar of correct dimensions to protect end frame and bearing.
3. To install a new bearing, place a flat plate over bearing and press in place until bearing is flush with outside of end frame. Support underside of end frame with a hollow cylinder while pressing in bearing.
4. Always install a new seal with replacement bearing. Press seal in place with lip of seal toward rotor. Coat seal lip lightly with oil to aid in reassembly.

INSPECTION (ALL MODELS)

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. Avoid producing flat spots. Slip rings may be lathe turned .002" (.05 mm) undersize. Slip rings are not replaceable. Excessive damage will require rotor replacement. Inspect brushes for wear. Clean with acetone if necessary. Replace brushes if excessively worn.

Scheme 15

REASSEMBLY (ALL MODELS)

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 a nut and washer at one end and a screw and washer at opposite end. Install capacitor. Capacitor attaching points are end frame and heat sink.
2. Position regulator in rectifier end frame. Install indicator light resistor and brush holder over regulator. Install screws securing regulator. On SI series, place diode trio on rectifier bridge and attach to regulator with insulated screw.
3. Place stator on end frame. Route leads over rectifier bridge studs and secure stator with nuts. Install brush springs and brushes in holder. Insert a straight wire or pin through hole in end frame and holes in bottom of brush holder. This will hold brushes in place until rotor is assembled into frame.
4. Place rotor in a 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. (54-82 N.m). Install rotor to rectifier end frame. Ensure scribe marks are aligned. Remove wire holding brushes. Install through bolts through end frames and tighten.

ALTERNATOR SPECIFICATIONS

DELCO-REMY "DELCOTRON" ALTERNATOR TEST SPECIFICATIONS

See also:
• TROUBLE SHOOTING - BASIC PROCEDURES