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John Deere – 1023E, 1025R and 1026R – Disassemble and Inspect Alternator

[1] –
→NOTE:
Clamp sheave in soft jaw vise and use an impact wrench to remove pulley
nut. Do not overtighten vise.

Remove sheave nut (A).

[2] – Use a puller to remove sheave (B).

[3] – Remove three screws (C) securing alternator rear cover to alternator.

[4] – Loosen positive post flange nut (D) enough to pull insulator (E) clear of rear cover.
Remove rear cover.

[5] – Remove four voltage regulator screws (F) and black brush screw (G).

[6] – Remove regulator and brush assemblies.

[7] – Remove four screws (H) retaining rectifier to alternator body.

[8] – Straighten the four wire leads (I) to allow removal of the rear half of alternator case.

[9] – Separate the two alternator case halves.

[10] – Remove retainer plate (J).

[11] – Press bearing (K) from case.

[12] – Inspect bearing (L) for smooth rotation. Replace if necessary.

[13] – Inspect slip rings (M) for dirt or rough spots. If necessary, use No. 00 sandpaper or 400-grit silicon carbide paper to polish rings.

[14] – Measure outer diameter of slip rings (M). Replace rotor if less than specification.

[15] – Check continuity between slip rings (M) using ohmmeter or multimeter. Replace rotor assembly if there is no continuity.

[16] –
→NOTE:
Use an ohmmeter that is sensitive to 0—1 ohm.

Check continuity between slip rings and rotor core (N). Replace rotor assembly if there is continuity.

[17] – Inspect stator for defective insulation, discoloration, or burned odor.

[18] –
→NOTE:
Set ohmmeter to the K Ohm range.

Check for continuity between each stator lead and body. Replace stator if there is continuity.

[19] – Check continuity between lead (O) and each diode lead (P). Reverse ohmmeter leads and recheck. There should be continuity in one direction, but not the other. Replace diodes or rectifier plate if bad.

[20] – Measure length of brush (Q) protruding from holder. Dimension should be within specification. Replace brushes if length is less than minimum.

[21] – Check continuity between brush (R) and terminal (S). There should be continuity only at these points. Repeat procedure for other brush and terminal. There should be continuity only at these points.