1. Remove the alternator from the vehicle (see «Removal and installation of the generator»).
2. Remove the voltage regulator (see «Checking and replacing the voltage regulator with a brush holder»).
3. Unscrew the three nuts securing the rectifier unit and the two nuts securing the terminal spacers «plus» and generator excitation terminals...
4....then remove the bushings.
5. Unsolder the six leads of the stator winding...
6.... and remove the rectifier unit from the generator.
Note. This is how the removed rectifier unit looks from the side of the protective casing...
... and so - from the stator side.
It looks like a capacitor, which is non-removable.
7. Check «negative» diodes by connecting «positive» (red) tester probe to «negative» plate (tire) rectifier block, and «negative» (black) the probe in turn to the three contact leads of the diodes in three places (in one) stator windings. If the diodes are good, the tester will show 580-620 ohms.
8. Connect «negative» (black) tester probe to «negative» rectifier plate, and «positive» (red) probe in turn to the same three contact terminals. If the diodes are good, the tester will show infinite resistance.
9. If the tester shows low or close to zero resistance, then the diode «broken», if the tester reading tends to infinite resistance regardless of the color of the connected probes, then the diode «in the cliff». In both cases, the rectifier unit must be replaced.
10. Check the same «positive» diodes, but only relatively «positive» rectifier block or output plates «B+» generator.
11. Check the stator winding tester for an open circuit (solid line diagram) and for the absence of a short circuit to the starter housing (diagram with dotted lines). When taking measurements, make sure that the winding leads do not touch the generator cover.
12. Mark the relative position of the generator covers...
13.... unscrew the four tie bolts...
14.... and, prying with a screwdriver, remove the generator cover from the side of the slip rings.
15. Remove the stator from the cover.
16. Inspect the stator. On its inner surface there should be no traces of armature touching the stator. If there is wear, the bearings or alternator covers must be replaced.
17. Install the spanner wrench on the nut and through its hole, insert the hex wrench into the hole in the shaft. Loosen the nut with a ring wrench, holding the shaft from turning.
18. Remove the spring washer and pulley from the rotor shaft.
19. Remove the rotor shaft from the bearing. If necessary, screw the pulley fastening nut onto the rotor shaft and press the rotor shaft out of the bearing through the wooden spacer with light hammer blows.
20. Inspect drive side cover (complete with alternator bearing).
21. If, during rotation of the bearing, play is felt between the rings, rolling or jamming of the rolling elements, protective rings are damaged or there are grease leaks, replace the bearing, and if cracks are found in the cover, especially in the places where the generator is attached, it is necessary to replace the generator cover.
22. To replace the bearing or cover, unscrew the four screws securing the bearing thrust washer...
23.... and remove the washer.
24. Using an aluminum spacer, tap the bearing out of the alternator cover with light blows from a hammer.
25. Press the new bearing into the cover using an appropriately sized socket.
26. Inspect slip rings. If they have scuffs, risks, scratches, wear marks from brushes and other defects, the rings must be ground. If damage to the rings cannot be removed with sandpaper, turn the rings on a lathe, removing the minimum layer of metal, and then sand.
27. Check the resistance of the rotor winding with a tester by connecting it to slip rings. If the tester shows infinity, then there is a break in the rotor winding and it must be replaced.
28. Check the absence of a short circuit in the rotor winding to the housing by connecting the tester leads to any slip ring and the rotor housing. The tester should show infinity.
29. Check up ease of rotation of the bearing from slip rings. If during the rotation of the bearing there is play between the rings, rolling or jamming of the rolling elements, the protective rings are damaged or there are grease leaks, the bearing must be replaced.
30. To do this, press the bearing off the rotor shaft with a puller and press on a new one using a suitable mandrel, applying force to the inner race of the bearing.
31. Examine a generator cover from slip rings. If cracks are found, the cover must be replaced.
Note. Replace all parts in specialized workshops or at an authorized dealer, since the cost of spare parts is quite high, and replacing parts is laborious, using professional tools. In addition, in these cases, a qualified diagnosis is required. After the repair, the generator must be tested on a diagnostic stand. Such a stand imitates the real operation of a generator with variable loads, while at the same time continuous monitoring of the charging voltage and current is carried out. Based on the results of the inspection, the contractor provides a guarantee both for spare parts purchased and installed by him, and for the repair and diagnostic work performed.
32. Assemble the generator in the reverse order of disassembly, orienting the generator covers and the stator housing according to the marks made earlier.