Rectifierregulator

GENERAL

The rectifier-regulator, manufactured by Tympanium, is a series regulator with a shunt control. The circuit combines the functions of rectifying and regulating. Figure 5-11 shows the schematic diagram.

The circuit essentially is a full wave bridge made up of two SCR's (Silicon Controlled Rectifier) and two diodes — SCR1, SCR2, D1 and D2.

Each SCR has a control gate which turns it "on" or "off" (makes it conduct or not conduct). When the alternator voltage is too high, both SCR's turn "off," the current paths are blocked, and the battery is not charged. When the voltage lowers to an acceptable level, the opposite happens and the battery is charged.

The rectifier-regulator has a set, pre-determined "on-off" voltage built into it. This value is determined by Z1, R1 and R2. These components are factory adjusted so that when the voltage gets above 14.5 volts nominal, the SCR's are turned off.

The battery voltage is sensed through D3, R2, Z1, and R1. When the voltage at the point between Z1 and R2 exceeds 14.5 volts - it turns Q1 "on" which, in turn, turns 02 "off." Thus, Q1 and 02 form a flip-flop circuit where when one is "on" the other is "off" and vice versa. With 02 "off," the current can't flow to the gates. This means the bridge essentially has been opened and there is no current flow to charge the battery.

LEGEND

Silicon Controlled Rectifier SCR

Transistor Q

Diode D

Resistor R

Capacitor C

Zener Diode Z

Battery B

Figure 5-11. Tympanium Rectifier-Regulator -Schematic Diagram

As soon as the voltage gets below 14.5 volts at the point between Z1 and R1 the opposite happens. Q1 turns "off," 02 turns "on," current flows to the gates, the bridge is closed and there is current flow to charge the battery.

In summary, the active elements of the regulating circuit are: Q1, Q2, SCR1, and SCR2. The elements of the sensing circuit are D3, R2, Z1, and R1.

One of the advantages of a series regulator is that there is automatic reverse polarity protection. If the battery is connected backward in a normal bridge, there will be a dead short. Not so in this circuit, because the SCR's simply can not be turned on.

To prevent high voltage build up, shunting SCR3 and SCR4 have been added. These SCR's simply short out the alternator winding when the voltage gets too high. The shunt regulator voltage setting is 40 to 50 volts. When this voltage is reached, current flows through zener diode Z2 and resistor R8 which turns "on" the shunt SCR's. Turned "on," the output is directly shorted.

CHECKING CHARGING SYSTEM

ELECTRICAL CHECKS

GENERAL

When the charging system fails or is not charging at a satisfactory rate, as is visually evidenced by a weak battery and dim lights, it is recommended that the following checks be made.

PRELIMINARY CHECKS

Battery: Check for weak or bad battery. See Battery Section. Battery must be fully charged for following electrical tests.

Wiring: Check for corroded or loose connections in charging circuit. Rectifier-regulator base must have a good, clean, tight connection for proper grounding.

If the preliminary inspection shows components to be in good condition, make the following electrical checks.

Regulating Voltage Check: (See figures 5-12 and 5-13.) Connect an ammeter in series with the alternator output. Connect load rheostat (carbon pile) and voltmeter across battery. Check regulating voltage while running engine at 3600 rpm.

Adjust load rheostat (or carbon pile) to 3.5 amperes output. The voltage readings then should conform to the values given by the curves shown in figure 5-14 at the temperature measured at the time of testing. For example, if the air temperature was +75°F, the upper voltage (from upper curve) would be 15.0 volts and the lower voltage (from lower curve) would be 13.8 volts.

Figure 5-12. Test Arrangement with Individual Components

5-16

Figure 5-13. Test Arrangement with Sun VAT-26 Tester

TEMPERATURE COMPENSATION CURVE

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2. Remove the clutch, primary chain and compensating sprocket. See "Disassembling Clutch."

3. Remove the starter motor and housing and disconnect wires from solenoid.

4. Remove the four mounting bolts securing the inner primary housing to the engine. The two rear bolts are safety wired.

5. Remove the four nuts and washers securing the inner primary to the transmission. Loosen the transmission to frame mounting hardware.

NOTE

On some 1980 models, the two rear studs, washers and nuts have been replaced by washers and bolts.

Figure 5-14. Regulating Voltage

Output Check: Run engine at 2000 rpm and adjust load rheostat (carbon pile) to obtain a constant 13.0 volts. The alternator output current should be 14 amperes minimum for 1978-1979 models and 15.5 for 1980 models.

Check Stator and Rotor: Make resistance checks. The coil resistance should check 0.2 to 0.4/Y(very low) across the contacts of the plug with an accurate ohmmeter. If found to be either open or shorted, the unit is defective. Also using an ohmmeter, check each pin to ground. There should be no continuity to ground (open circuit) as indicated by a reading of 1/2 megohm minimum.

Check AC output voltage with an AC voltmeter. It should be 19 to 26 volts per 1000 rpm. If there are shorted turns, the voltage will be reduced.

If the above checks are unsatisfactory, stator and rotor should be disassembled and checked for physical damage. As a final check, substitute components known to be good and check again. If the substituted units perform okay, the original units probably were defective.

Check the Rectifier-Regulator: If the rectifier-regulator appears to be the defective component, check it by replacing it with a unit that is known to be good and check again. Electrically disconnect the unit to be checked, then temporarily connect in the new unit. If the output is now okay, the original rectifier-regulator was defective and should be replaced. If the output is still unsatisfactory, the original unit was probably okay and the problem lies elsewhere.

REMOVING THE ALTERNATOR

WARNING

Disconnect the battery cables (negative cable first) to avoid accidental start-up of vehicle and possible personal injury.

1. FX Models — Remove the foot shift pedal.

FL Models — Remove the footboard, muffler and exhaust pipe from the left side.

6. Disconnect the hoses attached to the rear of the chain housing and remove the housing. Remove the O-ring from the engine.

7. See Figure 5-15. Using Puller, Part No. 95960-52A, pull the alternator rotor from the engine sprocket shaft.

8. Remove the two screws securing the starter plug. Remove the four screws, two lock plates and stator.

Figure 5-15. Pulling Alternator Rotor

CLEANING AND INSPECTING ALTERNATOR

The alternator rotor or stator may be replaced individually if either is damaged. The stator windings can be checked out with an ohmmeter as described previously in this section.

Remove all foreign particles from rotor magnets and clean rotor and stator before reassembling to engine. Rotor can

5-17

4. Attach the inner primary to the engine using the original four bolts and washers. Place the two bolts with the heads drilled through into the rear mounting holes. Tighten all four bolts to 18 to 22 ft-Ibs torque. Safety wire the two rear bolts together.

5. Align the transmission case so the inner primary does not bind on the mainshaft or mounting hardware. Tighten the inner primary to transmission mounting hardware to 18-22 ft-lbs torque. Then tighten the transmission to frame mounting hardware to 18-22 ft-lbs, also.

Figure 5-16. Installing Alternator Rotor be cleaned in petroleum solvent but do not clean stator in this solvent. Clean stator by wiping with clean cloth; do not use liquid cleaner of any kind.

Figure 5-16. Installing Alternator Rotor be cleaned in petroleum solvent but do not clean stator in this solvent. Clean stator by wiping with clean cloth; do not use liquid cleaner of any kind.

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