The speed of LTN-485 cdrom

My friend give me a LTN-485 cdrom and I fixed it by replacing the Spindle motor driver IC TA8493AF, but when I test the speed of the cdrom using NERO CDSPEED, it shows 8X at CLV,not 48XMAX at CAV. So ,I wonder whether the FW was replaced by other one.
Can somebody tell me something (hardware,such as PCB mark,FW version etc.)about the orginal LTN-485?
Thank you.