As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TAXI OUT SMOKE CAME OUT OF ELECTRICAL PANEL. AIRCRAFT RETURN TO BLOCKS WITHOUT INCIDENT. LOCATED THE SOURCE, GLARE INSTRUMENT WHITE LIGHTS BALLAST TRANSFORMER. DEACTIVATED GLARESHIELD AND INSTRUMENT WHITE LIGHTS AND ENTERED ON DMI 15265 AS PER MEL 33-1 CAT C.