please go to
www.psxcopyworld.co.uk and look at the boot instructions there and try them.
If your AR2 is 1.9 or earlier, you might be in business; if not then I don't expect AR2/v2 to work on the older PS2.
If you know who chipped the PS2, ask them what chip it is (hopefully NEO2.x). Otherwise just take the top off and look at the chip and how many wires. 8 is good, 5 is good if it's a NEO2.5 (there will also be a ribbon cable coming from the mod).
Let us know.