Hi Whino,
Tyros5 doesn't actually have a permanent internal clock. To set the time and current date, the T5 must be connected to a Wi-Fi router which should also be connected to the Internet via the Yamaha "UD-WL01" USB Wireless LAN adapter. You can find the necessary settings for this in the Wireless LAN display of the T5.
Note: If the T5 is not connected to the mains for a period of time (several days), the internal time and date settings may be lost, because there is no internal battery, only a so-called "super capacitor", which only can provide power for the internal clock for a limited time.
Best regards,
Chris
