What was found
DURING CLIMB, ODOR OF BURNING RUBBER APPARENT. SOON AFTER SMOKE EMINATED FROM STANDBY COMPASS HOUSING. SWITCHED OFF STBY COMPASS LIGHT WHICH WAS SELECTED ON. CB E75 TRIPPED SHORTLY THEREAFTER. SMOKE DISSIPATED AFTER STBY COMPASS LIGHT WAS SWITCHED OFF. DECLARED EMERGENCY & RETURNED TO DEPARTURE. DUMPED FUEL & LANDED UNDER MGLW AT 3999,500. ATB REPLACED STANDBY COMPASS IAW AMM 34-22-23. REPLACED STANDBY COMPASS INTEGRAL LIGHTING CONNECTOR IAW WDM 33-12-03. LIGHTING OPS CK OK 23-13-00.