Keeps Going Into Sleep Mode

My Powerbook goes to sleep quickly after 30 sec, hit space bar & the screen comes back on then goes to zzzzzzzzzz in 30 sec again.

May be of use [or not] I just installed a used optical drive [works fine] and logic board and then the track pad does not work. Check the connections & pins on the track pad and when I put it back together the over sleeping problem started. Track pad still does not work I'm using a mouse now.

Any suggestions I what or where to check next to keep this PB awake?

thanks

John