The DC offset on your amp is probably off. If you can't adjust DC offset yourself you need to get it to a competent technician.

In all probability, one of the power transistors has failed or is going bad. That is the likely culprit.

Send it in for service.

McGooserton wrote:

 

My 4 year-old Cambridge azur 540A has CAP5 protection circuitry that shuts off the amp when it detects high constant voltage. 

 

It kicked in maybe once or twice a year before, but in the past couple months it's been several times a week. I have to unplug the amp from the back every time. What might be causing the high voltage? I may have done a poor job of stripping the speaker wire and pulled out too many wire strands--would that affect the voltage?