What was found
ON ARRIVAL, FOUND WHEN STANDBY POWER SWITCH IS PLACED TO BATTERY, LOST ALTITUDE, SPEED & VERTICAL SPEED INFO & SCALE ON CAPT PFD & TAS ON CAPT ND. 1ST OFFICER WORKING. WARNING ELEX & GND PROX SYS STATUS MESSAGE FAULT PRESENT. INTERMITENT. T-SHOOTING FOUND SWITCHING ADC SOURCE TO ALTERNATE ON CAPT SIDE, FAULT DISAPPEARS, WHEN SWITCHING ADC SOURCE TO ALTERNATE ON 1ST OFFICER SIDE, FAULT PRESENT. REPLACED LT ADC IAW MM 34-12-01-4. NO HELP, FAULT PRESENT. ORIG PART REINSTALLED. REPLACED STANDBY POWER CONTROL PANEL IAW MM 24-33-04-4. NO HELP, FAULT PRESENT. ORIGINAL PART REINSTALLED. FAULTS CORRELATED TO LT AOA. R & R LT AOA IAW AMM 34-12-03-4-99. TESTED IAW AMM 34-12-03-6. TEST PASSED, ACFT OK TO CONTINUE.