Insert a flathead screwdriver between the alternator front bracket and the stator and use the screwdriver as a lever to pry the (down) generator front bracket.
Attention! Do not insert the screwdriver too far to avoid damaging the stator winding.
It may be difficult to remove the alternator rear bracket because the circlip used to secure the rear bearing is in the way. To facilitate rear bracket removal, heat the bearing assembly with a 200 watt soldering iron.
Pic. 7.38. Removing the alternator bracket
Do not use a heat gun for heating, as this may damage the rectifier diodes (pic. 7.38).
Secure the rotor in a vise with the pulley side up.
Pic. 7.39. Unscrewing the pulley fastening nut
Loosen the pulley nut, remove the spring washer, then remove the pulley and spacer (pic. 7.39).
Remove the alternator front bracket and two o-rings.
Remove the rotor from the vise.
Loosen the screws securing the brush holder and rectifier unit. Then unscrew the output nut «IN» generator.
Remove the stator assembly from the rear bracket
Remove the dust ring from the brush holder.
Before removing the stator, unsolder the three wires of the stator winding from the main diodes of the rectifier unit.
Attention! When soldering/desoldering contacts, be careful that the heat from the soldering iron affects the diodes as little as possible. Perform these operations as quickly as possible.
Attention! Be careful not to apply excessive force to the diode pins.
Before disconnecting the rectifier unit from the brush holder, unsolder the two pins soldered to the rectifier unit.
Rotor check
Pic. 7.40. Checking for a closed circuit between slip rings
Check for an open in the rotor winding. Check for continuity between slip rings (pic. 7.40). If there is too little resistance (tends to 0), it means there is a short circuit. In the event of an open circuit in the rotor winding or a short circuit, replace the rotor assembly.
Resistance: Approximately 3.1 ohms.
Pic. 7.41. Checking the absence of a short circuit in the rotor winding «mass»
Check that the rotor winding is not shorted to «mass». Check for continuity between slip ring and core. If there is a closed circuit (short circuit «mass») replace rotor assembly (pic. 7.41).
Stator check
Pic. 7.42. Checking for a closed circuit between the stator winding terminals
Check for an open in the stator winding. Check for continuity between the stator winding terminals. If the winding circuit is open (resistance tends to infinity), then replace the stator assembly (pic. 7.42).
Pic. 7.43. Checking the absence of a short circuit in the stator winding «mass»
Check the absence of a short circuit in the stator winding for «mass» (there is no closed circuit between the stator winding and the core). If the circuit is closed (resistance tends to zero), then replace the stator assembly (pic. 7.43).
Checking the positive output of the rectifier unit
Pic. 7.44. Checking the positive output of the rectifier unit
Using an ohmmeter, check that the circuit between the terminal «positive» diodes of the rectifier unit and the output of the stator winding is closed (little resistance). Reverse the polarity of the ohmmeter probes and measure the resistance (if the resistance is small, i.e. the circuit is closed in both directions, then the diode is broken) (pic. 7.44).
Replace the rectifier assembly.
Checking the negative terminal of the rectifier unit
Pic. 7.45. Checking the negative terminal of the rectifier unit
Using an ohmmeter, check that the circuit between the terminal «negative» diodes of the rectifier unit and the output of the stator winding is closed (little resistance). Reverse the polarity of the ohmmeter probes and measure the resistance (if the resistance is small, i.e. the circuit is closed in both directions, then the diode is broken) (pic. 7.45).
Replace the rectifier assembly.
Checking the three diodes of the rectifier unit
Test three diodes by connecting an ohmmeter to both terminals of each diode. For each diode, the circuit must be closed in only one direction.
Pic. 7.46. Checking the three diodes of the rectifier unit
With no closed circuit in both directions (or if there is a closed circuit in both directions) the diode is faulty and the rectifier unit (together with a cooling radiator) to be replaced (pic. 7.46).
Brush replacement
Pic. 7.47. limit line
Replace brushes if brush wear reaches limit line. Limit line: 2mm (pic. 7.47).
Unsolder the brush wire and remove the alternator brush with spring.
Solder the brush wire to the brush holder.
Assembly
Assembly is carried out in the reverse order of disassembly. Pay attention to the following:
Before installing the rotor in the rear bracket, insert a thin wire into the small hole in the rear bracket to secure the raised brushes. The wire should be removed after installing the rotor.