List out exactly what is going wrong so we can help you better. Material you are welding, how you have the Tig rig hooked up and what make and model it is, tungston type and size, how are you preping your tungston, what shielding gas you are using, what CFH, what cup??? Pictures tell a good story also. Its hard to give an answer with the info you posted. SA200's can flip polarity for a few reasons and that could be a problem. You should be hooked up for straight polarity DCEN, your ground will be on the + lug.