Pen tray solutions
One pen tray problem which sometimes occurs is when you pick up a pen and the light does not go on. This can be caused by a dirty optical sensor.
Use a cotton tipped swab (Q-tip) and some rubbing alcohol, to clean the optical sensors on the pen tray. If that doesn't solve the problem, call SMART tech support, give them the serial number of your SMART Board and serial numbers on the pen tray, and ask for a new pen tray.
A couple times a year, someone asks me why the lights on the SMART Board pen tray keep lighting up over and over again. It's normal for them to light up two times (polling in sequence: blue, green, eraser, red, black) whenever you connect to a computer's USB port.
Suspect the gray wire that goes from the SMART Board SC9 controller to the pen tray. It looks like a RJ11 phone wire, although it's pinned differently. The easiest way to test this is to take this wire off a known good SMART Board and swap it out. If the pen tray lights perform normally, then you know the wire is bad. Call SMART tech support and ask them to ship you:
93-00506-00 Cable 12C 25-1/2" pen tray to SC9 (for SMART Board 680)
93-00506-00 Cable 12C 20" pen tray to SC9 (for SMART Board 660)
93-00506-00 Cable 12C 14" pen tray to SC9 (for SMART Board 640)
When asking for a new pen tray OR replacement cable, give tech support the serial number of your SMART Board AND the model number and manufacturing date of the pen tray. In the above example, the pen tray was manufactured on May 30, 2005.