You mentioned to me in a PM that this machine is from Australia. The nameplate on the front says "IGT Sovereign". A Google search of that term yielded a few results, mostly reel slot machines that I think were also from Australia.
I moved this topic out of the S+ forum since it's certainly not an S+, but I'm not sure that this is a PE or a PE+, either. I agree that the board is similar in nature to the PE/PE+ generation of machines, but I don't think it really belongs to either of those. If anyone who has worked on Australian IGT machines can chime in, I'm sure that would be helpful. Unfortunately, I don't have much information about the machine you have.
One note, in the picture you posted, the transformer on the tray is unplugged from the MPU board (big block in the corner of the MPU tray/board). While I hate to point out the obvious, I presume you plugged that in when you were doing your testing?