For interest sake try it with and then without the adapter board in the prom 1 socket. (EDIT: Forget this the adapter is definetly for U3 socket)

Also are you sure the part numbers you PM ed are the only ones on the board?  Is the manual you have from this machine 'ROCK'?  If so what part number is the CPU board in the manual??

Also please tell me what jumpers are on the board?  Also from your photo it looks like IC numbers U17, U18, U19, U24, U25 and U26 are not installed, although this is not totally clear from the pics?  Can you cofirm these are the missing ICs and do they look like they were ever installed?  This will give me an idea of what version board you have?  Reason we need to know all this is to acertain where the EPROM should be installed and what jumpers may need modifying?  Reason is to acertain if someone has changed this board at some stage as System 80, 80a and 80b are not interchangable without modification due to the ROM used.

As such the board wont run if it is not jumpered correctly for your new EPROM.