Service Manual Delco-Remy CS-130 and CS121 Type Alternator Years Used: 1986-1996 Amperages: CS-130/85-105 amps CS-121/61-74 amps Used as the most common standard unit on GM cars & light trucks. also used in industrial, marine, agricultural and other applications.

INTRODUCTION The CS-121 and CS-130 Alternators are a complete departure from the SI series alternators that they were designed to replace. The new features include a high ampere output per pound of weight, and a totally new and different regulator. A diode trio is not used. A Delta stator, a rectifier bridge, and rotor with slip rings and brushes are electrically similar to earlier models of alternators. (Figures1 and 2)

The CS stands for Charging System, and the 121 and 130 denote the outside diameter in millimeters of the stator. By noting this number, the relative size and relative amperes output between alternators can be compared. The CS-121 and CS-130 features sealed bearings with lifetime lubrication in both end frames. A conventional fan mounted next to the pulley pulls air through the assembly from the rear for cooling. An internal fan mounted on the rotor pulls air through the slip ring end frame to cool the rectifier bridge, regulator and rear bearing. The air is expelled through openings in the end frame. No periodic maintenance on the alternator is required.

OPERATING PRINCIPLES

Unlike other charging systems which have three wires connected to the alternator, the CS-121 and CS-130 may be used with only two wires connected to the alternator. The output wire to the battery positive and an "L" terminal wire connected to the charge indicator bulb, or to the resistor, or to both. A basic wiring circuit is shown (Figure 3). The charge indicator works in much the same way as on other charging systems-the indicator lights when the switch is closed, and then goes out when the engine is running. If the charge indicator is on with the engine running a charging system defect is indicated. For all kinds of defects, the indicator will glow at full brilliance. A new feature of this regulator is that it will cause the charge indicator to be on with the engine running if the system voltage is too high or too low. The regulator is temperature-compensated; that is, its voltage setting varies with temperature. As in other alternators, the regulator limits the system voltage by controlling the rotor field current. Unlike other regulators, this regulator switches the field current on and off at a fixed frequency of about 400 cycles per second. By varying the on-off time, the correct average field current for proper system voltage control is obtained. At high speeds, the on-time may be 10% and the off- time 90%. At low speeds with high electrical loads the on-off time may be 90% and 10% respectively. The use of the "P", "F", and "S" terminals is optional. The "P" terminal is connected to the stator, and may be connected externally to a tachometer or other device. 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 a voltage, such as battery voltage, to sense the voltage to be controlled. For complete circuit, reference must be made to the vehicle manufacturer's wiring diagrams. Where the regulator is identified with an "I" marking on the regulator case, the circuit in Figure 3A applies. In this circuit, both the "L" and "I" terminals serve to turn on the regulator and allow field current to flow when the switch is closed. The "I" terminal may be connected directly to the switch, or through a resistor. Both are illustrated. The "I" circuit may be used with or without the "L" circuit; that is, with or without anything connected to the "L" circuit. The vehicle circuit can be identified, Figure 3 or Figure 3A, by observing the terminal marking on the regulator, which will be either an "F" (Figure 3) or "I" (Figure 3A).

TROUBLE SHOOTING A basic wiring diagram is shown in Figures 3 and 3A (above). When operating normally, the indicator bulb will come on when the switch is turned on, and will then go out when the engine starts. If the indicator operates abnormally, or if an under-charged or overcharged battery condition occurs, the following procedure may be used to diagnose the charging system. Remember that an undercharged battery is often caused by accessories being left on over-night, or by a defective switch which

allows a bulb, such as a trunk or glove box light, to stay on. This alternator does not have a regulator by-pass test hole.

Observe the following procedure: I. Visually check belt and wiring and load check battery . II. Go to step V. for vehicles without charge indicator light. III. With ignition switch on and engine stopped, light should be on. If not, detach harness at alternator, use fused jumper to ground "L" terminal lead on harness. Be very carefully to properly identify "L" terminal lead.

Grounding "L" terminal should cause indicator light to light. If lamp does not light, locate open circuit between grounding lead and ignition switch. Bulb may be bad. IV. Switch on, engine running at moderate speed. Light should be off. If not, stop engine, turn switch on, and detach wiring harness at alternator. A. If light goes off, replace or repair alternator. B. If light stays on, check for grounded "L" terminal wire in harness. V. Battery undercharged or over-charged. A. Detach wiring harness connector from alternator. B. With switch on, engine not running, connect voltmeter from ground to "L" terminal in wiring harness, and to "I" terminal, if used. Wiring harness may connect to either "L" or "I" or both. C. Zero reading indicates open or grounded circuit between terminal and battery. Correct as required. D. Re-connect harness connector to alternator, run engine at moderate speed with all electrical accessories turned off. E. Measure voltage across battery. If above 16.0, replace or repair alternator. NOTICE: The alternator may be O.K. on vehicles using "S" terminal if "S" terminal wiring has excessive resistance which will cause high voltage. Refer to vehicle wiring diagram. Correct wiring as needed, then re-check voltage. F. Connect ammeter at alternator output terminal. Connect voltmeter across alternator. Turn on accessories. load battery with carbon pile to obtain maximum amperes output. Maintain voltage at 13.0 or above. 1. If within 15 amperes of rated output, alternator is O.K. 2. If not within 15 amperes of rated output. Check belt for slippage or replace or repair alternator.

ALTERNATOR REPAIR

To repair the alternator, observe the following procedure. DISASSEMBLY Note or mark the front to rear housing relationship, this is the "clock" Position. You must know it for re-assembly. Then remove the 3 thru-bolts and separate the drive end frame assembly from the slip ring end frame assembly. The stator should remain in the rear (D.E.) housing. To remove the drive end frame from the rotor, place the rotor in a vise, using wood blocks or brass jaws so not to damage the rotor then tighten only enough to permit removal of the shaft nut, or hold rotor with hex wrench in end of shaft when removing nut. To disassemble slip ring end frame (Figure 4) proceed as follows: 1. Punch out cover rivets, or pins, (figure 4), and discard cover.

2. To separate stator from end frame assembly. cut off or unsolder the leads at rectifier bridge terminals. 3. Remove stator. 4. Punch out baffle pins, Figure 4, remove baffle. 5. Carefully note the position and internal connections so reassembly can be made correctly as shown in Figure 5. 6. Detach fasteners, lift brush holder, regulator. and rectifier bridge from end frame. 7. Unsolder or un-crimp, as needed, the connector to disconnect regulator from rectifier bridge, and from brush holder.

ROTOR, FIELD WINDING (Stator) CHECKS

STATOR CHECKS If an ohmmeter reads low or lamp lights when connected from an stator lead to bare metal on the test the delta stator for shorts or opens. Noticeable discoloration at any place on the assembly usually indicates defective stator windings.

Connect test lamp or ohmmeter from one slip ring to rotor. If lamp lights, or if reading is low, the rotor winding is grounded (Figure 6). 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, replace rotor. If the rotor is not defective, but the alternator fails to supply rated output. the defect is in the rectifier bridge. stator, or regulator.

RECTIFIER BRIDGE CHECK The rectifier is the number one failed component on the CS-130 alternator. To check rectifier bridge, connect ohmmeter using low scale from bridge terminal to heat sink, then reverse connections (Figure 8). If both readings are the same. replace the rectifier bridge. Connect from other two terminals to heat sink in same manner to check other two diodes. Connect between three terminals and base plate (Figure 8) to check remaining three diodes in rectifier bridge. Notice: Some digital ohmmeters cannot be used to check diodes in rectifier bridge. Consult REGULATOR The regulator cannot be checked with an ohmmeter. Use only an approved tester to test regulators of this type. BRUSH HOLDER If the brushes are to be reused, clean with a soft, dry, cloth. Replace the brush holder assembly if brushes are excessively worn. SLIP RING SERVICING

It 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. CAUTION: The rotor must be rotated in order that the slip rings are cleaned evenly. Cleaning the slip rings by hand with-out spinning the rotor may result in flat spots on the slip rings, causing brush noise. Slip rings that 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 REPLACEMENT The drive end bearing is sealed on both sides and requires no added lubrication. The bearing inner race is a slip fit over the shaft. A drive end frame assembly is shown in Figure 9. Torque the shaft nut to 54-108 N M (4680 lb.-ft.). The slip ring end bearing assembly is covered in the next section.

REASSEMBLY 1. Discard bearing retainer ring, Figure 4. 2. Install new ring. 3. To install new bearing. push on outer race until bearing bottoms in end frame. This procedure is not yet completed, see Step 12 after alternator is completely assembled. 4. Position regulator. rectifier bridge, and brush holder on work bench flat surface, solder or crimp connectors as in original assembly. Hold brushes in holder with pin. 5. To dissipate heat and make electrical contact place Copper heat Transfer grease, part no.698-T on end frame casting under rectifier bridge. 6. Position assembly in slip ring end frame, assemble fasteners. 7. Assemble baffle, use punch to drive pins down flush with baffle. 8. Seat stator securely against end frame, solder three stator leads to rectifier bridge terminals. 9. Install cover, use punch to drive pins flush with cover. 10. Push on both inner and outer race of slip ring end bearing to assemble end frames together. II. Assemble thru bolts. Remove brush holder pin. 12. With alternator assembled, push on both inner and outer race so slip ring end bearing seats

GENERATOR BENCH CHECK To check the alternator in a test stand, proceed as follows:

Make connections as shown in Figure 11, except leave the carbon pile disconnected. The ground polarity of alternator and battery must be the same. The battery must be fully charged. Use a resistor of any value between 35 ohm, 5 watt, and 500 ohm. 1/2 watt between battery and "L" terminal. This procedure applies to both circuits, Figures 3 and 3A. 2. Slowly increase alternator speed and observe voltage. 3. If the voltage is uncontrolled and increases above 16.0 volts, the rotor field is shorted or grounded or the regulator is defective, or both. A defective rotor field coil can cause the regulator to become defective. NOTICE: The battery must be fully charged when making this test. 4. If voltage is below 16.0 volts, increase speed and adjust carbon pile to obtain maximum amperes output. Maintain voltage above 13.0 volts. 5. If output is within 15 amperes of rated output. generator is good. 6. If output is not within 15 amperes of rated output, alternator is defective and requires repair or belt is slipping.