Theta Data basic transport Blue light?

Hello All,

   I just aquired a second Theta data basic transport for parts mainly and I noticed the one I just got has a blue light next to the remote sensor? My first data does not have that. Can someone tell me what it is for? What it might mean? I do not have a manual to look it up. And btw if anyone has a manual for the Theta data basic transport  please let me know.
Its possible that light on your old one is not working. Also, if I remember correctly, ST was an option on that transport. The light may come on when you use it.
There were I think two  Theta data basic's MkI and MkII, maybe you can search for an instruction book on the MkII.

Cheers George 
That's the main power LED. Lights when main power switch in back is on. Theta recommended leaving it on, while the Standby switch in front powers down the display and other circuits. They also recommend turning the main power switch off when going on extended time away. They say this is best for sound quality.