I am new to this forum, and this hobby for that matter. I recently picked up an Onkyo M-5140 amp on the cheap from craigslist (it had not been used in at least a year but was rumored to be working). It worked fantastically for about a week nothing abnormal. One day during play, speakers stop emitting sound, some relay clicks, protection light comes in. After several hours off the unit will power up and play normally. However, after about 15 minutes the same problem described above happens. I have opened it up and used DeOxit, same symptoms remain. I have not been able to detect any abnormally hot components either as that was my first concern. Any obvious guidance would be helpful. I'm currently trying to find a service manual as well. Can anyone tell me the difference between an Onkyo M-5140P and Onkyo M-5140? I've been told that the P only designates systems that came with remotes and therefore the service manual should be one and the same, but that comes from the seller so there is a conflict of interest I'm concerned about.