Lincoln Electric SQUARE WAVE IM467-B Operator's Manual page 43

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TROUBLESHOOTING GUIDE
SYMPTOM
Machine has gas flow and high frequency but no
open circuit voltage when the Arc Start Switch
or Amptrol is pressed.
Difficulty in getting tungsten to "light off".
Machine welds only at minimum output when
the Current Control switch is in the REMOTE
position.
Arc goes out soon after it is lit.
NOTE: STARTING DIFFICULTIES MAY OFTEN BE DUE TO NOT PRESSING THE AMPTROL FAR ENOUGH.
WHEN THE AMPTROL IS JUST "CRACKED", THE MINIMUM CURRENT (2 AMPS) IS PRODUCED. PRESSING
THE AMPTROL MORE AT THE START OF THE WELD WILL OFTEN SOLVE STARTING PROBLEMS. Refer to
page 23 for proper use of amptrols.
TROUBLESHOOTING
TIG WELDING (Continued)
1. Turn High Frequency Switch OFF. Look at the two LED's in
the upper left corner of the Power PC board. They should
glow when the Arc Start Switch is pressed.
If the LED's do glow, leads 232A and 233A may be reversed
on the primary of control transformer T5 in control box. Turn
the machine off. Reverse the leads. Turn back on and check
for open circuit voltage. If this does not fix the problem,
restore wires 232A and 233A to their original positions.
If the LED's do not glow, the Power PC board may be defec-
tive. Replace. If the problem still exists, the Control PC board
may be defective. Replace.
1. Current Control switch is in REMOTE but machine is being
used with an Arc Start Switch and no Amptrol. Set switch to
LOCAL.
2. Start switch is ON, and Start Current is set too low for tung-
sten size. Either turn Start switch OFF, or increase Start
Current to proper level for tungsten size.
3. Current control is set too low. Amptrol is not being pressed
far enough for the tungsten size being used. Try in LOCAL
Current Control at a higher current setting. SEE NOTE
BELOW.
4. Contaminated tungsten. If tungsten becomes contaminated
with foreign materials, grind off end of tungsten to expose
fresh electrode. Grind to a point for DC work and leave an
end for AC work.
5. Incorrect tungsten type. Pure or zirconiated is recommended
for AC welding; thoriated is required for DC welding.
6. No shielding gas (or not enough). Adjust gas flow for 10 to
30 CFH (4.7 to 14.1 l/min) for most applications.
1. Current Control switch is in REMOTE but machine is being
used with an Arc Start Switch and no Amptrol. Set switch to
LOCAL.
2. Use LOCAL Current Control. If problem goes away, Amptrol
may be defective. Replace or repair Amptrol.
3. Current Control switch may be defective. Replace.
4. Can machine be preset for currents from 2 to 400 amps? If
not, see "Cannot preset a current" in General
Troubleshooting section.
1. Current Control is set too low, or Amptrol is not being
pressed far enough for the tungsten size being used. SEE
NOTE BELOW.
2. In AC, use Continuous High Frequency.
SQUARE WAVE TIG 355
Observe Safety Guidelines
detailed throughout this manual.
CAUSE AND REMEDY
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