Recently we installed a site for Cingular in which they where using TMA's surge arrestors and Bias T's. We installed the co-located tested all the lines and all passed w/ very good sweeps. About a month later we received a call stating that there was no power getting to the TMA's. We troubleshot, replaced, and reswept. To find that the issue was not resolved. After speaking to others w/ more RF knowledge than I have they all seemed to think there was problem w/ our line or a jumper although all the sweeps indicated that it was all good. After not being able to sleep that night, I laid there and thought what could it be. And then it hit me, a couple of months prior we had received a set of ( surge arrestors which had visible defects from they manufacturer. The next Monday we went out w/ new ones and replaced them. It worked. The surge arrestors where letting signal go out but but when the TMA tried to respond back to the PDU it was giving it an error message do to the surge arrestor. Lesson Learned. Start @ the bottom and work up. I hope anyone who has this problem or is currently sitting there and wondering what else can I do will see this post and it helps them.