[Fred R]

Thanks Ron. That is the kind of info I was looking for. I have all the schematics but only a few service bulletins. I do know the crackling noise is not in the power stage but somewhere in the driver stage on both sets. Pulling the 6F6G (or the 42 in the 680X) the power stages are absolutely quiet.
By the way, here's a story on my 38-690. It belonged to a friend of mine who paid someone to restore it. I knew the fellow who did the rebuild and it was a fine job. My friend introduced me to his fiance and the first thing she said to me was "Hi I'm Nancy and I hate radios". Needless to say, within a month he called me to see if I wanted to buy it. I think it cost me about $400 and that was over ten years ago. The only thing I did with it was to remove paint off both chassis. Someone who owned it before my friend had painted both chassis with silver paint. They were not rusted. I can only guess they wanted it to look like a Scott. After about three evenings and paint remover and some q tips, it looks like it should now.

Fred