What was found
PASSING 3000 MSL, ALL THREE SCREENS LOST ALL DATA. ONLY THE GRAY LINES REMAINED. TCAS FAIL MESSAGE APPEARED ALONG WITH A COUPLE OF OTHER STATUS MESSAGES. CAPTAIN PRESSED HIS PFD BUTTON AND THE CENTER SCREEN REAPPEARED AND SHOWED THE EICAS SCREENS. CAPTAIN AND FO SCREENS REMAINED BLANK EXCEPT FOR THE GRAY LINES. UPON CREW DEBRIEF CONFIRMED ALL THREE SCREENS BLANK. CYCLED L/C/R GGU C/B'S AND PERFORMED LDS RTS TEST PER AMM 34-22-99-5. ALL THREE SCREENS DISPLAYING NORMAL, HOWEVER L GGU HAS FAULTS 656, 644, 643. R GGU HAS FAULTS 655, 642, 641. ALL THESE FAULTS ARE XTALK RELATED AND PRESENT WITH C GGU INOP PER FIM REF ABOVE. REF WRI 31-31/5263 FOR C GGU MEL. REMOVED AND REPLACED C GGU IAW AMM. OPS CHECK GOOD. ACFT OK FOR SERVICE.