As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING PRE-FLIGHT CHECKS ON THE RAMP, THERE WAS A BURNING ODOR IN THE COCKPIT AND SMOKE WAS OBSERVED COMING OFF THE CAPTAIN'S SIDE OVERHEAD CEILING PANEL IN THE COCKPIT. AIRCRAFT POWER WAS SHUT DOWN. MAINTENANCE INVESTIGATION REVEALED A BURNED RHEOSTAT ON THE DIMMER CONTROL FOR THE CAPTAIN'S OVERHEAD LIGHT. THE PANEL ASSY WAS REPLACED WITH NO FURTHER FAULTS.