The hot can (cardboard wrapped) is made by GE and its specs are printed on the can as 60-100 micro farads at 350v. I’m concerned about the range of uF as I need to specify a uF rating for them to build a new one. Should I specify 100uF or something in the middle like 80uF?
@ccogopher This kind of power supply is known as a ’voltage doubler’ supply. The cap in the insulated can is floating- its insulated in paper so you don’t get a shock from it. It carries a lot current and so is usually the first part to fail as the filter caps age.
100uF is fine- no worries, especially if you have replaced the original rectifiers, which were pretty sketchy. Obviously a good quality part for that cap is a very good idea- and its mate of the same value. I would find 105C parts for installation if you can find them. 'Snap' caps might be a way that you can find the value and they could be mounted with cap clamps.
This is a very nice sounding amp once properly restored- its worth being careful and as neat as you can with the restoration!!