TROUBLESHOOTING

 

 

 

 

 

 

 

 

 

 

 

 

TROUBLE

 

 

CAUSE

 

 

WHAT TO DO

 

 

A. Machine fails to hold the “heat”

 

 

1.

Rough or dirty commutator.

 

 

1.

Commutator should be turned

 

 

consistently.

 

 

 

 

 

 

 

or cleaned.

 

 

 

 

 

2.

Brushes may be worn down to

 

 

2.

Replace brushes.

 

 

 

 

 

 

limit.

 

 

 

 

 

 

 

 

 

3.

Field circuit may have variable

 

 

3.

Check field current with ammeter

 

 

 

 

 

 

resistance connection or

 

 

 

to discover varying current. This

 

 

 

 

 

 

intermittent open circuit due to

 

 

 

applies to both the main

 

 

 

 

 

 

loose connection or broken wire.

 

 

 

generator & the exciter.

 

 

 

 

 

4.

Electrode lead or work lead

 

 

4.

Tighten all connections.

 

 

 

 

 

 

connection may be poor.

 

 

 

 

 

 

 

 

 

5.

Wrong grade of brushes may

 

 

5.

Use Lincoln brushes.

 

 

 

 

 

 

have been installed on

 

 

 

 

 

 

 

 

 

 

generator.

 

 

 

 

 

 

 

 

 

6.

Field rheostat may be making

 

 

6.

Inspect & clean the rheostat.

 

 

 

 

 

 

poor contact and overheating.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B. Welder starts but fails to

 

 

1.

Generator or exciter brushes

 

 

1.

Be sure that all brushes bear on

 

 

generate current.

 

 

 

may be loose or missing.

 

 

 

the commutator and have proper

 

 

 

 

 

 

 

 

 

 

spring tension.

 

 

 

 

 

2.

Exciter may not be operating.

 

 

2.

Check exciter output voltage

 

 

 

 

 

 

 

 

 

 

with voltmeter or lamp.

 

 

 

 

 

3.

Field circuit of generator or

 

 

3.

Check for open circuits in

 

 

 

 

 

 

exciter may be open.

 

 

 

rheostat, field leads and field

 

 

 

 

 

 

 

 

 

 

coils. Check rectifier bridge.

 

 

 

 

 

4.

Exciter may have lost excitation.

 

 

4.

Flash fields. (1)

 

 

 

 

 

5.

Series field and armature circuit

 

 

5.

Check circuit with ringer or

 

 

 

 

 

 

may be open-circuited.

 

 

 

voltmeter.

 

 

 

 

 

 

 

 

 

 

 

 

 

C. Welding arc is loud and

 

 

1.

Current setting may be too high.

 

 

1.

Check setting and current output

 

 

spatters excessively.

 

 

 

 

 

 

 

with ammeter.

 

 

 

 

 

2.

Polarity may be wrong.

 

 

2.

Check polarity. Try reversing

 

 

 

 

 

 

 

 

 

 

polarity or try an electrode of the

 

 

 

 

 

 

 

 

 

 

opposite polarity.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(1)See FLASHING THE FIELDS on following page.

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Lincoln Electric 350-SA manual Trouble Cause What to do