broken

i have genius sw-hf5.1 sound system http://img161.imageshack.us/my.php?image=subnjuferrs5.jpg satellites are working fine, but the subwoofer isn't working. i opened it, and it has 4 amp ICs, 3x TDA7269A, and 1x TDA7296. TDA7296 is obviously for the woofer, and i'm wondering how to test if it...