Schematic wanted for Bell A.D.T. effect

[justbass]

Hi all I'm new on here and am doing some research on behalf of a friend who is a guitar tech. His boss uses A.D.T. effects and we're trying to find as much information on them as possible due to their age. As the title suggests I'm looking for a schematic either for a Bell version or any other make or type.
Any info anyone has would be very usefull.
Thanks Justin