Thinkpad T60 LCD turns off affter a couple of minutes.

[jerrydaughtrey]

Thinkpad T60 Type 2007-CTO LCD turns on and after a couple of minutes turns off. I Can view on external monitor and everything functions correctly. If I use the f7 key and cycle through the external, LCD and then both again, the LCD will come back on for a couple of minutes. I have changed the inverter. HELP