Bartosz:
If you are measuring current when the board is active in full operating state then I would expect the majority of the current to be:

43 mA for ADuC812 in normal mode (data sheet 16 MHz)
70 mA for 62256 SRAM Operating mode (Hitach data sheet)
09 mA for D5 LED if lit
09 mA for D1 Display LED
09 mA for green Power LED
04 mA for OP491 Opamp(x8) (worst case .5 ma/amplifier)
01 mA for 7805 and HC573 (these two very small current)
----------
145 mA Total

I would expect this to be about what you should see for current draw for this board. So why 290 mA? Check the following things:

1) Use a separate meter inline with the power source to check the current draw. I have seen many a variable voltage power supply whose built in meters were broken or completely off scale.

2) Using a separate volt meter, make sure that the voltage you are supplying the board is about 9 volts. Volt meters in some power supplys are total junk.

3) Re-consider the handling that this evaluation board has had. Is it possible that it may have been subjected to an ESD jolt. One hit of static electricity to an IC or microcontroller pin can fuse the silicon on the chip by the pin into a low ohms resistance. A couple of damaged pins at 60 ohms each could easily contribute to the excess current draw you are seeing on the board. Eval boards of this type are particularly susceptable to ESD damage because many, if not all, processor pins are brought out to pins, connectors and/or headers.

Michael Karas