while i don't know the pin outs of the a590 i can tell you that most computer gear with a 5 pin power connector would have +12 -12 +5 and 2 ground lines you can find the -12 by reversing the probes on your multimeter (set on voltage) what i mean is putting the positive lead on the ground and the ground lead on the -12 you will get a positive 12 reading or if you don't reverse the leads of the meter that the meter will pull down past zero
but i don't know if this would work for you but what i did with gvp impact was to use my continuity meter to check the pins in the din to the pins on the hard drive power connector and found that they are all direct connected to the din all except the -12 so i took a PC power supply and cut off one of the molex connectors and replaced it with a female then connected it directly to the gvps molex minus the -12 (because on a molex its just has +12 +5 and 2 ground lines) and it seems to works fine even with out the -12
john
VJ AIWAZ
