Standby switch before FWB?

[joesatch]

Why a CT on a bias winding?

[sluckey]

Probably used for more than just bias. Schematic would reveal all.

[joesatch]

 

[PRR]

It says "Accessory"??

That's a terrible scan of a terrible schematic. Marshall must dump the design straight to a PCB stuffer without actually looking at it.

The two 15V rails are logically for the too many opamps in there.

31V sounds shy for EL34 at high power but what do I know?

FWIW, I was just reading a book which suggested that half-wave bias supplies are a figment of the past and we should be spending the penny for the other diode. (However the PT lead costs more than the diode.)

[joesatch]

This amp has the standby switch located before the FWB (in pic). Any issue with that? I've gutted this amp and am rebuilding it with a custom pcb. The iron and hookups will remain as will the standby switch.  Any issue with this? Should i add back a 1n caps in parallel to  the diodes as shown. looks like one of the 1n's to rectified DC and the other to ground? Smoothing caps to reduce pop i guess. Never seen two used and hooked like that though

[pdf64]

DC is harder on switch contacts than AC.
The ‘snubber’ caps are good practice to reduce buzz interference that solid state rectifiers can cause.

[joesatch]

i may snubber it.

https://diyaudioheaven.wordpress.com/tutorials/power-supplies/snubbering/