Fronius AccuPocket 150/400 TIG Operating Instructions Manual page 61

Tungsten electrode melting
Tungsten inclusions in base metal during the ignition phase
Cause: Incorrect tungsten electrode polarity
Remedy: Connect the TIG welding torch to the (-) current socket
Cause: Incorrect (or no) shielding gas
Remedy: Use inert shielding gas (argon)
VRD does not light up even though no welding process is taking place
Cause: VRD option not present
or internal device fault
Remedy: Contact after-sales service
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