www.avahifi.com/70rebuild.htm
This site has a reprinted article that explains in depth exactly how to rebuild/upgrade a Dynaco St-70. Very long, extremely detailed, step-by-step instrucions. I think you will find it very informative. It's on the Van Alstine website. He is currently no longer modding the St-70, but his does offer a complete re-make of the amp with new circuit board design using your old chassis and transformer.
This site has a reprinted article that explains in depth exactly how to rebuild/upgrade a Dynaco St-70. Very long, extremely detailed, step-by-step instrucions. I think you will find it very informative. It's on the Van Alstine website. He is currently no longer modding the St-70, but his does offer a complete re-make of the amp with new circuit board design using your old chassis and transformer.