HF fault?

[rory1]

i went to use the tig this morning and i seem to have a problem witht the HF,

machine is STEL 161, lift start works fine but when you switch over to HF its farting and spluttering and you dont get the nice HF whine. its as if im getting a very random pulse?

any common faults on the HF side of machines that i should be aware of??

cheers

 

[Robotstar5]

Don't know if it's relevant but prevoius threads have mentioned spark gap adjustment for HF, not sure if it applies to your machine though.

 

[Wedg1e]

Break in the insulation somewhere so the HF is jumping to earth elsewhere than the workpiece?