What was found
DURING VECTORS TO FINAL, DU NR 1 FLASHED SEVERAL TIMES BETWEEN A BLANK SCREEN AND A RED X FOR ABOUT 5 SECONDS. CHECK DU NR 1 EICAS MESSAGE, FLASHED ONCE DURING THIS TIME. ACRID SMELL WAS PRESENT BUT SMOKE VISIBLE, DISPLAY RETURNED TO NORMAL. FOUND DUI UNIT SMOKED, REMOVED & REPLACED NR 1 DUI OPS CHECKED SATISFACTORY. ALL WORK DONE IAW CESSNA 750 MM CHAPTER 34-25-01.