What was found
6 MILES FROM IAF OKAVE FOR RNAV 35 INTO KRXE SMELLED SOMETHING ACRID & LOOKED AROUND COCKPIT. SAW A SMALL BIT OF WHITE SMOKE COMING OUT FROM LOWER RT OF INSTRUMENT PANEL. SAW ANOTHER PUFF OF SMOKE & A FAINT FLICKERING LIGHT IN REFLECTION OF THE PNEUMATIC PRESSURE GAUGE. TURNED OFF PANEL LIGHTS & TURNED OFF OTHER ELECTRICAL SOURCES, LOOKED AT CIRCUIT BREAKER PANEL & VERIFIED NO TRIPPED BREAKERS. CONTINUED TO MONITOR PANEL & FIRE THERE WAS DID NOT APPEAR TO SPREAD OR WORSE. SMOKE STOPPED EMANATING FROM PANEL. TOLD ATC I HAD A POTENTIAL ELECT FIRE & THEY ASKED IF I WANTED TO DECLARE AN EMERGENCY & ASKED IF I NEEDED ANY ASSISTANCE. SINCE ISSUE APPEARED TO ME TO BE UNDER CONTROL, DIDN’T WANT TO DECLARE & DIDN’T NEED ANY ASSISTANCE SINCE WAS IN VMC SO CLOSE TO DESTINATION & SUFFERED NO LOSS OF SYSTEMS OR CONTROLS. ALREADY HAD CLEARANCE, CONTINUED APPROACH & LANDED IN VMC. AFTER LANDING, BROUGHT FLAPS UP & TURNED OFF AVIONICS & BATTERY MASTER SWITCHES, CALLED FLT SERVICES HAD LANDED SAFELY. AT NO POINT DID IT SEEM NECESSARY TO ENGAGE COCKPIT FIRE EXTINGUISHER. MECHANIC FOUND THAT A PANEL CONTAINING THE DIODES FOR INSTRUMENT BACKLIGHTING WAS THE CULPRIT. ONE OF THE DIODES HAD SHORTED & ARC CREATED FLASHING & SMOKE. THE LIGHT PANEL WAS REMOVED AND PANEL LIGHTS WERE DEFERRED.