I have a Shugart Model 801. From the manual it requires 120vac, +24vdc, +5vdc and -5vdc. I have a Mean Well power supply Model RD-125B, that outputs both +24vdc and +5vdc. Can I user a step down converter to convert the +24vdc to -5vdc? There are several listed on eBay. Would I be better off just to buy a -5vdc wall adapter?