You need to open that zip file, which may result in having a circuit diagram that can me examined and some useful advice being obtained. otherwise there is not enough information available to offer any useful advice. It appears that this box requires an external power source, but what that may be is not clear.

The bass box on my version of the A200 has a small transformer mounted near the PCB which is putting out about 15VAC so probably a 12V DC rail. I am thinking of removing it from the box has as it is causing a fair amount of mains hum. It would be nice to have a circuit schematic as that zip file does not have one.

Moderator edit: New thread created from this.

 

In the one photo there are two yellow wires to a connector tagged "AC in", so it may be that the power transformer is part of this assembly. But if this device is a "recovered item" then we have no clues.

Using recovered items requires the ability to analyze what is present and understand what is missing.. That is a valuable skill set not held by many.