you have to configure what kind of output it needs to spit out.
ii it's the same as the DX, I think you press and hold the button on the side and power it on then release the button... you then press until the light combo on the other side next to the video ports is a particular sequence for the kind of output you need. some of the newer ones you hold the button, power it on and you just keep pressing the button to cycle through each resolution...
some of the older PB systems have different ways to change the resolutions, so you'll have to find the manual for your particular box and see the proper sequence to change it.