Last Saturday I finally got my second to burn-out Ampeg PF-500 to my closest authorized Ampeg repair center. Had a discussion with their service/repair tech about the PF series of amps. He said: They are quite aware of all the problems with the 500's and he thought they we're up to Rev. "J" on the main boards, (mines a Rev. "C".) He wasn't doing any warranty repairs on the PF's, Ampeg was just sending a new unit to the buyer. (My 500 isn't under warranty) He said he could try to repair my main board but I'd be money ahead to just toss the head. He suggested I contact Ampeg to see if they'd make available a main board and I could try the repairs myself, but he doubted they'd sell me a new main board. (My e-mail to Ampeg asking for help with a "out of warranty" PF-500 was answered with "Our hands are tied.") He recommends that if your gonna use Ampeg, stick with their big iron. So, my impression of this is..... If you have a PF series head and your under the warranty your golden, have a failure and you'll recieve a brand new head. Out of warranty and have a failure, it would seem Ampeg hasn't any provisions for repairs or parts for these amps. I'm sure there are more and more amp manufacturers that are going with everything on a main board as the PF's are, and I know every amp manufacturer has problems..... It's in HOW they deal with the problems.