Originally Posted by vegedge
mine is identical to his. maybe more scratches but it has the numbered panel if i can ill post a picture.
what was the stock grill cloth that year? i've seen silvery, natural and mine which is black and a bit silver
Until the mid 70's Sunn only used two types of grill cloth;
This is mid 1969 and later grill cloth
The Sunn on the left has the pre ’69 cloth
The old Sunn’s grill cloth has seen many smoky bars over the last 45 years, it was actually a few shades lighter gray when it was new.
Originally Posted by bubbastain
Here are some more pictures. I've decided it's a keeper(for now) so I'll probably get a pair of KT88s and replace some old resistors, upgrade the can cap thing and the SS rectifier. Where can I get pretty specific details on parts list and procedures for this? I'd like it to be a as reliable as can be. I will also consider leaving as is, except for maybe a new set of tubes if doing the upgrades will be too much. It does currently work just fine, doesn't make any weird noises and sounds really good.
That amp looks relatively untouched, the only newer stuff I see at a glance are those trendy orange drops, and those are in the tone stack; the "motor" looks for the most part unmolested.
Which may be good or may be not so good. I'd leave it alone until something breaks.
A total re-do is always tempting, but the problem with that is to do it right it's all or nothing.
Although the filter caps can and sometimes do last for a looooong time, odds are the ones in your amp are probably way
overdue for replacement. This would definitely explain your early distortion issues; not 100% for sure
the reason, but by far the most likely
reason for the lack of power.
The tube rectifier is probably the reason
the filters have held up so well, SS rectifiers blast the circuit will full power instantaneously when you hit the power switch, not at all good for capacitors or many other components. Tube rectifiers slowly ramp up the juice as they heat up; kinda like using a variac every time you turn the amp on. Much more component friendly.
However, refurbishing the power supply will show the other
components more current than they have seen in a long time, and failures can occur in a "domino effect" down the signal path; and upgrading to a SS rectifier will just amplify this effect.
It's like a vintage car; you replace a water pump and suddenly the previously solid heater core starts leaking.
Like I said "all or nothing". You might be fine just "bandaid'ing" a few things, or you might be opening a can of worms.
PM me if you need any assistance with parts info or availability, I can point you in the right direction.