A B767-200 IN CRUISE AT FL330 OVERWATER DIVERTED DUE TO EICAS AUTOPLT NO LAND 3 WARNING ACCOMPANIED BY STRONG ACRID ODOR IN COCKPIT.

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CENTER AUTOPLT DISENGAGED WHILE IN STEADY CRUISE; NONTURBULENT CONDITIONS. ASA ANNUNCIATOR INDICATED NO LND 3; AND A STRONG; ACRID ODOR WAS NOTICED BY CO; FO AND IRO. WE INFORMED ATC OF OUR INTENTIONS TO DIVERT BACK TO ZZZ. WE LATER AMENDED THIS TO ZZZ1; DUE TO A LESSENING OF THE FUME ODOR; AND UPON RECOMMENDATION OF OUR COMPANY. HEAT WAS NOTICED IN AREA OF CENTER AUTOPLT COMMAND SWITCH. CENTER AUTOPLT WOULD NOT REENGAGE. ACFT WAS FLOWN BACK TO ZZZ1 ON R AUTOPLT AND AN OVERWEIGHT LNDG WAS ACCOMPLISHED ON RWY 27L. NO EMER WAS DECLARED; HOWEVER; DIVERSION BACK TO U. S. WAS MADE DUE TO RVSM REQUIREMENTS AND POSSIBLE THREAT OF SMOKE. MAINT DISCOVERED A BURNED-OUT FLT CTL COMPUTER. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE CAUSE OF THE ODOR WAS AN OVERHEATED OR BURNED OUT FLT CTL COMPUTER LOCATED IN THE FORWARD EQUIP BAY. THE RPTR SAID THE HEAT NOTED ON THE AUTOPLT MODE CTL PANEL ENGAGE SWITCH MAY OR MAY NOT BE A CONTRIBUTING FACTOR. THE RPTR STATED MAINT REPLACED THE CENTER AUTOPLT FLT CTL COMPUTER AND IT WAS NOTED NO CIRCUIT BREAKERS WERE FOUND TRIPPED.