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 inter-

 

 

 

to discover varying current. This

 

 

 

 

 

 

mittent open circuit due to loose

 

 

 

applies to both the main genera-

 

 

 

 

 

 

connection or broken wire.

 

 

 

tor & the exciter.

 

 

 

 

 

4.

Electrode lead or work lead con-

 

 

4.

Tighten all connections.

 

 

 

 

 

 

nection may be poor.

 

 

 

 

 

 

 

 

 

5.

Wrong grade of brushes may

 

 

5.

Use Lincoln brushes.

 

 

 

 

 

 

have been installed on genera-

 

 

 

 

 

 

 

 

 

 

tor.

 

 

 

 

 

 

 

 

 

6.

Field rheostat may be making

 

 

6.

Inspect & clean the rheostat.

 

 

 

 

 

 

poor contact and overheating.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B. Welder starts but fails to gener-

 

 

1.

Generator or exciter brushes

 

 

1.

Be sure that all brushes bear on

 

 

ate 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 rheo-

 

 

 

 

 

 

exciter may be open.

 

 

 

stat, 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 volt-

 

 

 

 

 

 

may be open-circuited.

 

 

 

meter.

 

 

 

 

 

 

 

 

 

 

 

 

 

C. Welding arc is loud and spat-

 

 

1.

Current setting may be too high.

 

 

1.

Check setting and current output

 

 

ters 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 SA-250 manual Trouble Cause What to do