As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN THE PILOT WAS DOING A PREFLIGHT THE COCKPIT LIGHTING SYSTEM WAS TURNED ON, SMOKE AND FUMES COULD BE SEEN COMING FROM THE COPILOTS EDGE LIGHTED C/B PANEL. POWER WAS TURNED OFF AND INVESTIGATION REVEALED ONE OF THE BRASS TRIM SCREWS THAT ATTACHES THE EDGE LIGHTED PANEL TO THE COCKPIT SIDE WALL WAS CHAFING THROUGH A POWER WIRE BEHIND THE PANEL. THIS CAUSED THE SCREW TO GET HOT AND BURN THE LIGHTED PANEL ASSEMBLY P/N 90-364125-3.