Andy Evans wrote:
Since these items are worth around $1,000 in good condition, it might be wise
to take it to someone familiar with them before doing anything. You may want
advice on how to restore it to start with, before retro fitting anything and
chucking anything away. Keep all the bits, whatever you do - this kind of item
needs to be in original condition as much as possible for the real money. There
are support groups for these amps - you can ask on the Leak group, which is
=== Andy Evans ===
Thanks a lot Andy,
I´m a newbie to tube amp restauration but not to restauration at all,
normally I prefer working on motorcyles - the oldest of which, a BMW
R25/3 with sidecar has a few years more than the STA25.
I begun cleaning and examining the power amp today and now all the dirt
has vanished it looks really great! The paint is fine, the metal parts
not corroded, the chrome shiny again :-). Nothing broken, bent or gone
up in smoke, the inside looks pretty complete and functional.
The tubes still present are Mullard GB (EL34, EF86) and Mullard Canada
(ECF82), one EL34 was Valvo. I guess the Mullard was originally fitted.
I´m going to replace with Philips8 EF34, EF86) and Siemens (ECF82) NOS.
Hope this doesn´t make a difference or bother the purists.
One 8µ8F Capacitor and a small Resistor near its Counterpart on the
other side seem to have been replaced in an early age of the amp - they
do not match left/right but look as ancient as the rest of the parts.
As far as I can measure with my multimeter no big capacitors are
short-circuited, both speaker outputs measure 0.8 Ohm - with no tubes
yet fitted.
I would be glad to hear that this is the correct value and no shortcut
or something...
I´m going to proceed as adviced and power up with limited current first
to see if there are any leakages which are likely to lead to a damage.
And I´ll gladly put some more pictures of the restauration process on my
web site - watch out at
http://www.in4tec.de/PICS/RADFORD/luckyfind.html
Thanks a lot everybody for being very helpful!
Walther