Panasonic YC-400TX Manual page 24

Arc is unstable or result of welding is not
good.
Arc dies.
Tungsten electrode is excessively worn.
N.B.
Contact manufacture's agent if any abnormality occurs which does not correspond to the above
Troubleshooting Guide.
Polarity is not suitable.
Connection of input and output terminals is ineffective.
Welding current for tungsten electrode is too small compared with
current suitable for the diameter of electrode.
Tungsten electrode is dirty.
Welding current for welding rod is too small compared with current
suitable for the diameter of rod.
Distance between torch electrode and base mental is too long.
Welding current for tungsten is too high compared with current
suitable for the diameter of electrode.
Shielding gas flow is short or gas post flow time is short.
Shielding gas is not flowing.
TIG torch is connected to "+"terminal.
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