Weird, I'm actually having the same issue. My first pt pooped out on me in less than a week. Just got my replacement today. It does the same thing, like one second on...one second off. Using it directly on a brand new wall adaptor. And two brand new 2.0 sc tank cartos which according to what I have read should work fine right? Weird though because the first couple times I used it, it was fine. The last couple times, it has done that weird cycling thing. I swear all this ohm stuff is killing me and my check book. It's like a big maze I just can't figure out. I think I have it right and then I have to order something else over and over. Sorry, a little overwhelmed right now, don't mean to seem cranky.