I had mine modified for gain and my tech put gain pots on both channels and added a middle to the first channel.Among other mods.It screams!Reading this info it says fixed bias,but my tech says no it’s not,he might have added a bias adjustment during the mods?The serial # on my chassis is A 06124 and is the AB763 schematic.As they say in this info?Hopefully this might help you, Jeff.

To tell the year,I just checked my ’66 Showman,AB763 chassis,Brad shows you how to do it,look for the # on the body of the transformer it should read 606 for Schumacher and the next # is the yr. last 2 #’s are the week of the yr.Good info,I always thought mine was a ’63 so I was told by the person that gave it to me?The week # was 07 preceded by a 6,so mine is a ’66,I would think.Having such a low week #?

i have a blaceface dual showman that needed to have the fuse (2.5 amp slo~blo) replaced. i had switched on and off one too many times, and it did what it was meant to do. anyway, i got a free fuse from the electronic store, and am now running my guitar through a 2~12’’ speaker cabinet.