Urghhh surface mount with the numbers filed off - that's helpful! Have you hunted for the part numbers on the boards, that might find a manufacturer? It's unlikely they'll offer a schematic, but you may be able to obtain the PCB - though you may end up chasing a fault around all the boards!
Otherwise it's going to be a nightmare, particularly with the possibility of dedicated chips - that 60-ish pin could be a major problem to obtain if it's faulty, e.g. it may well have burned-in programming specific to the application.
Dave H. (the other one)
It's quite common at the budget end of manufacturing, when they've copied a chip manufacturer's example from the datasheet and don't want their product copied, and can't necessarily afford legal protection through patents/copyright, e.g. the board layout will be copyright as their intellectual property (the example circuit is given away free by the chip company to encourage use) but useless unless you know what's used where or the programming in the 60-legged chip.Why would they goto the trouble of filing off the numbers?
I could see it in a high-end machine with some sort of technology they didn't want reversed-engineered but a generic machine?
Or are they just using other components without permission/license or something?
I can't believe they would do it just to stop people repairing stuff themselves?
Although I'd suppose it would be easy enough to set up a machine to sand off thousands at once...