Maintenance Airframe; Maintenance Avionics; Maintenance Powerplant
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
General Maintenance Action
Aircraft
When hooking tow bar up to aircraft at end of check; noticed that the nose landing gear - taxi lights were on dim. Aircraft was on ground service for power. Ground service switch was cycled at lower panel. Taxi lights followed switch. The landing light switch in the cockpit was in the off position. When aircraft power was turned on and taxi light switch turned on; additional circuit breakers popped. Smoked was noticed in the cockpit. Aircraft power was turned off. Ground power plug was pulled and batteries disconnected. Avionics was called for troubleshooting. Damaged wiring was located in the lower aft section of the forward avionics compartment. Damage to wire bundles occurred in feed-through to right pack bay.
While on ground power; a maintenance technician noticed the nose taxi light was dimly illuminated. When aircraft power was applied and the taxi lights selected; several circuit breakers popped and smoked was noticed in the cockpit. Damaged wiring was identified in the avionics compartment.