Took a bit of a while to get everything apart but managed to undo the thing from the case. The unlocking mechanisms were all jammed up.
It was last certified to be good in 1975.
Inside, modular design, a bit rusty and dirty, missing the top shields, all the mounting screws missing.
It’s been worked on a fair bit in the past. Someone rather talented with a soldering iron stuffed this NPN into the socket then threw solder at it from a few feet away.
Pulled all the boards out and started to wipe it down. Then took a picture.
Little bit of surface rust, but overall in fairly nice shape.
Helpfully, somebody has removed the base at some time in the past and not put it back on. It does slot back into the cabinet and stay put, mostly.
Brought it up gently on the Variac. No smoke, sparks or anything untoward.
Pulled the front off. Unfortunately it got rained on and the front panel started to peel off. The bulbs have been replaced with the wrong type also.
The fascia has a thin transfer sheet stuck to it. The water had gotten in under it and caused it to ripple and wrinkle up.
Attempted to squeegee the water out and get it to sit flat. It kinda worked.
Brought it up with a pair of sacrificial speakers. Thought the preamp wasn’t working, turns out it needs to be jumpered into the main amp.
Cleaned the cabinet with oil soap, then carefully rubbed it down with 000 wire wool and re-oiled it.
Started measuring resistors and began replacing ones that are out of spec (+- 10%), trying to get within 2% for the replacements.
Quite a busy workbench. Table. Whatever.
All but one of the resistors on this board (20V Voltage regulator and 180 degree phase shift) were bad.
A number on the right hand preamp board were also bad.
Buttoned all back up again, looking mostly respectable. More to come.