Ron wrote in message
...
On 22/02/2011 22:13, Phil Allison wrote:
"N_Cook"

Instead of the original 3x 12AX7 it now has 2 and 2x 12AT7 and a 5AR4
rectifier


** You need to find a schem of the Bandmaster-Reverb Amp AA768.

Shame all the ones Google turns up are illegible.


.... Phil


I have the diags for AA768, it's not brilliant but fairly readable.
email me if you want a copy.

Ron

Ta for that, I have it in the Aspen Pittman Tube Amp vol 3 book which hapens
to be a very clear schematic.
I think I've found the distortion problem, duff 12AX7 socket pin. Remaining
problems are both large Tx only held to the chassis by wishful thinking. And
excess hum (for this owner), bad replacement pots (tagged, not the original
pcb ones). The output matcher had to be moved to accommodate a different
speaker, and not well mounted . Badly blanked off front panel holes for niow
deleted functions.
Other than the cab little seems original, o/p Tx, choke, knobs, chassis ,
valve bases and the jewel pilot lamp holder is about the sum of it
Luckily surplus Rexine in the amp cavity to salvage for where their pet
rabbit has eaten the exposed covering.
Researching the output bottles , nice little page about the company, I like
the "retro" industrial instrumentation
http://www.tubedepot.com/sed1.html
in operation since 1912 they presumably never lost the skill base