View Single Post
Old 24th Jan 2011, 10:29 am   #1
dsergeant
Octode
 
dsergeant's Avatar
 
Join Date: Mar 2006
Location: Bracknell, Berkshire,UK.
Posts: 1,169
Default Quad 44 Control Unit

This Quad 44 control unit suffers from a low level rustle, like some sort of electrolytic problem but it may be the volume control track. I cannot seem to nail it down, and it does seem to be worse after power on, tying in with the capacitor theory.

Although I have circuits in the user manual and have found a service manual, these both show the circuits for the earlier versions. Mine is s/no 24221, a very late one, and the tone control board where I suspect the problem lies is type 12784-1, rather than the earlier 12512-9, and it is very different. The volume control is a custom unit in rectangular black case which solders directly to the tone control board rather than flying leads on the earlier ones - if it is the volume control I cannot see it being available.

Does anybody by chance have the circuit of this later 12784-1 pcb, or any suggestions as to what is causing the problem.

Thanks
Dave
dsergeant is offline