Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Deric on November 24, 2018, 09:20:41 pm

Title: Standel S-80 - Schematic
Post by: Deric on November 24, 2018, 09:20:41 pm

I have a very clean (inside - ugly on the outside) Standel S-80 head. No matching cab. Has all original tubes. Tubes light up but filter caps are bad. No schematic to be found anywhere. Have started tracing it out.Any experience with these? Are they cool? Worth anything? A non-working "for parts" one recently sold on the 'bay for $550. Trying to decide if it's worth my time to get it working or if I should just sell it as is... Thoughts? Schematics?Thanks

Title: Re: Standel S-80
Post by: shooter on November 25, 2018, 10:11:26 am

here's a start for schematics;

http://standelamps.com/support/schematics/index.html

what to do?, only you know  :icon_biggrin:

Title: Re: Standel S-80
Post by: Deric on November 25, 2018, 05:30:18 pm

Thanks Shooter!


Found that site already.  That list starts from 1962 and seems to be all solid state.  This amp appears to be 1961-62 and is all tube. Two 12AX7, One 6U8A, two 6DQ6B, 5U4 and an OB3 regulator tube for the screen supply. 


I've started tracing it and am most the way through.  Will likely go ahead and get it up and running.


Been staring at it trying to figure out how to replace filters.  It has 2 x 20u/20u 500v twist lock cans.  Can't seem to find a direct replacement and even if I could I'm not sure I want to spend the $$.  I have a couple of 32/32 500v JJ cap cans that may fit with a clamp.  Not sure if the hole in the chassis is big enough though...  Could always gut and restuff the original cans...


Thanks!

Title: Re: Standel S-80
Post by: shooter on November 25, 2018, 05:54:04 pm

You can just "temp in" the JJs for Tshootin, sounds like you have a challenge  :icon_biggrin:

Title: Re: Standel S-80
Post by: mresistor on November 25, 2018, 06:07:07 pm

On the JJ cap cans going in a smaller hole, such as '60s Fender Champ/Princeton etc.  -  if you are very careful you can clamp onto the terminals with a pair of pliers and gently twist/rotate the terminal around on the cap can to reduce the circumference of the terminals and thus the size of the opening needed to mount it... then  cut a rubber inner tube or some similar rubber to create an insulated gasket for the cap can mounting.  You'll need to drill two holes into the chassis for the clamp.   The "adjusted" terminals will clear the hole..  Not sure you'd  want to do this to a '60s chassis of high value though. 


It takes some "feel" to determine if when trying to rotate a terminal that the terminal is moving on the wire and not twisting it..

Title: Re: Standel S-80
Post by: Deric on December 13, 2018, 01:20:27 pm

Filter caps replaced - JJ cans fit perfect.  Rebuilt the bias and all is good there.  0D3 regulator tube is working.  Decided to trace and draw a schematic before moving on to the preamp.


Not sure on pot values.  CTS pots from 1960.  Volume and accent pots are stamped FY8875.  Bass and treble pots are stamped FY8876.  Not sure if those are part #'s.  Measuring in circuit is appears the volume and accent pots are 500K and the treble/bass pots are 1M.  Also not sure on the cap value from pin6 to pin9 on the 6u8a and the power cap on the bass control.


Schematic attached.