Hi- I was given this keyboard by a friend and I'mlooking for the user manual and hope you can help. On the far right on the keyboard it says "LK-90tu" and under that "Key Lighting System" and "Smart Media." The only place I found a model # was on the power pac and it says-"Model AD-5UL" On the power pac there are also two series of numbers as follows; LR65893A and 820AG43004