This is the "Flight Data Subassembly," one of several components of the Voyager 2 attitude and control system. It was mounted in one of the segments of the main Voyager spacecraft frame. The items are flight-qualified spare hardware which were used in laboratory simulations to resolve in-flight problems encountered by the Voyager spacecraft.
Voyager 2 was an unmanned space probe which, in 1986, passed close to the planet Uranus to transmit images of its surface.
NASA's Jet Propulsion Laboratory tranferred this object to the Smithsonian in 1999.
Transfer from the Jet Propulsion Laboratory, California Institute of Technology