A B757-200's in-flight entertainment system overheated while airborne causing electrical fumes in the aircraft. An emergency was declared followed by a diversion to a nearby airport.

Narrative

Aircraft was at FL350 when a strong electrical burning odor was detected in the cockpit. Shortly thereafter; the #4 Flight Attendant called to say she had a smell of electrical burning followed by Flight Attendant #1 calling the telling us she also smelled electrical burning. An emergency was declared with ATC and transponder changed to 7700. ZZZ was the closest airport; so we asked for radar vectors with immediate descent. Emergency checklist was initiated; and flight attendants were telling us that passengers were complaining of the electrical burning smell. Short final into ZZZ; flight attendants reported that the smell had dissipated. An emergency evacuation would be evaluated after the aircraft came to a stop on the runway. Airport Rescue and Fire Fighting met the aircraft; an outside inspection of the plane was conducted and reported nothing unusual. The aircraft taxied to the ramp; followed by Airport Rescue and Fire Fighting. Station personnel handled the deplaning of the passengers.