As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 7686 TO PDX INSTRUMENT LIGHTS CIRCUIT BREAKER POPPED ACCOMPANIED BY BRIEF SPARKS AND SMOKE. INSTRUMENT LIGHTS WERE INOPERATIVE. MAINTENANCE INSPECTED WIRES AND SWITCHES AND FOUND DEBRIS ON RHEOSTAT. DEBRIS WAS REMOVED AND SWITCH POSTS CLEANED. AIRCRAFT RETURNED TO SERVICE.