Technics cant get surround sound to work wonder if i have all the connection wires as bought secondhand

Are you trying to use the surround sound for movies or music ? , ive got the dvd version of this system (sc-dv290) and ive noticed the surround sound tends not to perform well with music , but sounds great with movies. i think its because the movies have dolby digital and music does not. The dolby pro logic in my opinion doesnt really make that much of a difference in sound unless the sound is cranked up past 44db on the amplifier. the only cables you need are the ones that are attached to the surround sound speakers and they cannot be removed so it cant be the wiring . I reckon you have a 1 - faulty system 2 - listening to music 3 - maybe not pressing the pro logic button on the sound processor. Hope this helps