MBP external monitor

Hello, my LCD is broken on my MBP and I was trying to use a 32inch tv as the external monitor. It says no signal on the tv. I think the resolution is set so its unable to display on the tv. I have tryed connected the mac to an old crt monitor and it works fine. Is there a way I can change the resolution of the tv through the computer or set a default so all external displays are a certain resolution and change it from there. VGA connection. old silver MBP