What was found
A CUSTOMER SENT AUTOPILOT COMPUTER FOR REPAIR WITH THE DEFECT DESCRIPTION A/P WILL NOT DISCONNECT/DISENGAGE. BENCH TROUBLESHOOTING CONFIRMED THAT PITCH BOARD SOLENOID DRIVE TRANSISTOR Q211 WAS LEAKING CURRENT TO THE PITCH AND ROLL SOLENOID OUTPUTS J1922-3. THE TRIM SERVO CLUTCH DRIVE WAS NOT AFFECTED. FAILURE OF Q211 WOULD HAVE CAUSED THE PITCH AND ROLL SERVO SOLENOIDS TO REMAIN ENGAGED WITH THE AUTOPILOT DISCONNECTED. THE ONLY WAY TO DISENGAGE THE PITCH AND ROLL SERVOES WOULD BE TO PUSH AND HOLD THE AP DISCONNECT SWITCH OR TO PULL THE AP CIRCUIT BREAKER. THE PITCH AND ROLL CONTROLS WOULD APPEAR STIFF WITH THE AP DISENGAGED, HOWEVER, THE SERVO HAVE CAPSTANS WITH CLUTCH SETTINGS THAT CAN BE OVERPOWERED BY THE PILOT. TO CORRECT THE DEFECT, Q211 WAS REPLACED, THE KC 192 WAS FUNCTION TESTED AND RETURNED TO THE OWNER.