The resetting means that the Watchdog circuit is likely triggering somehow. Under normal circumstances, this happens when the CPU crashes. Try the following:
1) Measure the 5V rail on the JAMMA harness and make sure the board is receiving 5.0V . If so, try increasing it slightly up to 5.05V or 5.10V .
2) Try removing any socketed ROM chips. Blast out the sockets with compressed air and then reinstall the chips.
3) If you have an EPROM programmer, dump the CPU ROM chips and compare them against MAME. The CPU ROM chips should be labeled:
east-12-1.ic32
east-15-1.ic10
east-11.ic31
east-09.ic9