Mitsubishi ws-55511 dtv-comp input won't accept 1080i signal

I recently had my Mitsubishi ws-55511 repaired. It needed a convergence chip replacement as well as the 7 "capacitors" that usually go bad with it. When the "guts" were re-installed and everything was re-connected I no longer was able to get full HD signal from my cable box into the dtv-input on the rear panel. Before the TV(guts) left my house I was enjoying a very fine HD picture until I was having the red & blue blurring issue due to the convergence problem.  I can hook up the Blu-Ray dvd player to this input but, it only delivers a 480p picture. When the cable box is connected I get a blue screen telling me there's a problem with the the ybr connection check the cable, or it's an invalid connection. The box is fine according to the cable company.  What could've caused the dtv dedicated input to go out like this?  and it there something I can do to re-set it?  Help!!! I'm without this tv now for almost 2 months.