As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
150NM FROM SFO TO ELEC SMELL AND A LITTLE SMOKE IN THE COCKPIT. MODE CONTROL PNL AND AUTO THROTTLE KICKED OFF AND CB POPPED. SMOKE AND SMELL RAPIDLY DISSIPATED. FLT RETURNED TO SFO. MODE CONTROL PANEL P/N 822-0195-102 REPLACED. PRELIMINARY FINDINGS BY COMPONENTS SHOP INDICATE A FAILURE OF A CAPACITOR (C6) INSIDE THE MODE CONTROL PANEL P/N 822-0195-102 (UA MR22411-63).