Powerbook G3 Sound Problem

I have an old apple wallstreet g3 laptop. I bought it off of ebay. the sound doesnt work at all, it makes cracking sounds but thats about it. I tried putting a new working sound card in and still no luck. I recently tried putting my sound card in the same model laptop and it worked on somebody elses but not mine. No sound card seems to work! What could be the problem? is it the connection of the card to the board? I cant figure it out.. Thanks for your help

Hmm I wonder if the speakers are bad.