OK, it's time to post some information about my Mark III stereo amp project. It's moving ahead on several fronts, depending pretty much on my moods:
The A-431 OPT's needed some TLC. Here's a picture of the original. Note the exposed lams and windings...Huh. What happened to the original potting material? The covers were clean, nothing melted.
The cooker: A metal can with a 100w bulb heats it up to about 180F in a couple of hours. Moisture is driven out and the core temp is ready for potting. Wires have been replaced, fish-papered and taped:
High-Tech potting station: Hot plate used to heat microcrystalline wax, the same substance used by the original AcroSound and Dynaco manufacturer. When heated to 180F, it turns into a liquid similar to the consistency of paint thinner and penetrates much, much better than varnish. No need for vacuum pumps etc.
One down, one to go:
All resistance values were checked before and after to make sure nothing got broken. Good so far. Next post: Chassis and Poseidon boards.
Chris