Mitsubishi 4DQ5 Service Manual download pdf (Page 86)

Starter troubleshooting guide

Symptom

Possible cause

Bearings are dirty, or need

lubrication.

2) Rotor (armature core)

Large current

rubbing the pole pieces.

and low speed

3) Grounded coil in the armature

or in the field.

4) Short-circuit in the armature

coils.

1) Magnetic switch

grounded

and

not

working.

Large current

2) Grounded coil in the armature

but no speed

or in the field.

3) Seized bearing.

1) Open-circuited coil in the

armature or in the field.

No current and

2) Broken brush pigtail.

no speed

3) No conduction between

brushes and commutator

because

"high mica" con-

dition or dirty commutator

surface.

Small current

and low speed

Loose coil connection in the field.

and torque

Very large current,

very high speed

Short-circuited field coil.

and low torque

The best way

testing the starter

run it

under loaded condition,

but

that

requires special

testing equipment. For ordinary servicing

pur-

poses, the no-load test and troubleshooting guide

will do.

(2) Inspection after disassembly

(a) Using a ground tester or megger, check armature

coil and commutator for short circuit.

there

any continuity between commutator and ar-

mature shaft, armature coil and commutator are

short circuited.

-82-

670202

(b) A growler

generally used to test armature for

short circuit in its Winding.

Place armature on a

growler, and rotate it slowly while holding a steel

strip over armature.

there

any short circuit

between cores, the strip will vibrate and be

at-

tracted to armature.

so, replace armature.

Repair commutator

the runout exceeds the

limit.

Specifications Unit:

(in.)

Item

Assembly Repair Grinding

standard limit limit

Commutator

0.05

0.3

runout

(0.0020) (0.012) (1.22)

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Mitsubishi 4DQ5 Service Manual Page 86

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