I picked up this vintage Heathkit Phono amplifier in a trade with the intention of converting it into a guitar amplifier. It had a Phono/Line switch on the front which is a perfect location for a 1/4″ input jack.
The components in this unit have never been replaced, so I had low hopes of getting it working.
I couldn’t find the exact schematic for this unit, but the Heathkit AA-191 is almost identical, except maybe for a few component values.
This didn’t go so well. I think, similar to the Elk Pro-sonic restoration, the capacitors need to be completely replaced. Maybe I’ll do a part 2 when I have some time.