John-deere stx38 User Manual download pdf (Page 162)

4 - 78

3/21/97

REPAIR

ELECTRICAL

4. Clean stud terminal (F), replace if threads are

stripped or if it is corroded.

5. Replace insulator (E) if cracked.

6. Clean positive brushes (D )contact point with end

cap. Using Ohmmeter, check for

no continuity

between positive brushes (D) and end cap, and

also between stud terminal (F) and end cap.

Replace positive brushes (D) if

continuity

indicated.

7. Align upper highlighted markings (A) and carefully

assemble top end cap and armature into frame.

8. Compress brushes into brush holders of bottom

end cap using two thin screw drivers (G) or tongue

depressors.

9. Align lower highlighted markings (A) and carefully

assemble starter so brushes are positioned

against commutator of armature.

10. Carefully remove screwdrivers without allowing

brushes to dislodge from holders of bottom end

cap as assembly goes together.

11. Install long cap screws (B) and tighten them evenly.

12. Install starter in reverse order of removal.

REPAIR STARTER ARMATURE

IMPORTANT: DO NOT clean armature with solvent.

It can damage insulation on windings. Use

mineral spirits and a clean brush.

1. Clean commutator of armature with a coarse, lint

free cloth. DO NOT use emery cloth. If

commutator is badly grooved, turn it down on a

lathe or replace it.

2. Check for short circuits with a growler.

3. Rotate armature on growler while holding a steel

strip (e.g. hacksaw blade) on armature. Strip will

vibrate in area of short.

NOTE: Shorts between bars are sometimes caused by

dirt or copper between bars.

If test indicates short circuited windings, clean

and recheck. If still faulty, replace armature.

4. Check for grounded windings with an ohmmeter or

test light. If any

continuity

is indicated, winding is

grounded and armature must be replaced.

NOTE: Armature windings are connected in parallel,

each bar must be tested.

5. Check for open windings with an ohmmeter or test

light. If

no continuity

is indicated, there is an open

circuit and armature must be replaced.

M55917

M55919

M46892

M55923

M55924

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John-deere stx38 User Manual Page 162

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