Dell Vostro 1700 display problem

I have a dell vostro 1700 laptop displays for about a minute then goes black I can shut lid then open it comes back on but goes off again after another minute. It does it with the hard drive out too. External monitor works fine.Is there a lid switch I cant find one. Thanks

 

There might be a lid switch hidden in one of the hinges however it is unlikely that this is your problem.

How far does the laptop "go" before the screen goes black? As in, can you log in to Windows or does it get stuck at the boot screen?

Do you have an external monitor you can test with?

 

the laptop boots into windows fine also works on external monitor. Its just the laptop screen goes off after a minute then you can shut lid and open then it comes back on then it goes off again till you shut lid and open it.