What was found
AT GATE ON APU GEN & PACK 2 NOTICED BURNING SMELL IN FLIGHT DECK & FOUND PRESS SPIKE & CONTROLLER DISPLAYED WENT BLANK, NO DISPLAY. ALSO NOTICED CB F8 POPPED. OPENED DV WINDOWS TO RELIEVE CABIN PRESS. REMOVED DIGITAL CONTROLLER & FOUND TO SMELL BURNT DIS-CONNECTED CONNECTOR & FOUND CB F8 STAYS IN. INSTALLED DIGITAL PRESSURIZATION CONTROLLER CONNECTED CONNECTOR CB F8 POPS. REF AMM 21-31-01. R & R DIGITAL CONTROLLER IAW AMM 21-31-01. OPERATIONS CHECKED GOOD IAW AMM 21-31-00.