I use a Dell Power Supply -- 500W/41A with my charger. I've used it with an OFNA truer. For some reason it popped the internal voltage/load protection a couple of times at first, but then I trued about 10 tires right after that with no problems. (It resets internally in just a couple of seconds...).
The nice thing -- they're CHEAP. If you want to know more, PM me -- I can even hook you up with one.