I have a Sansui AU-517 that is in PROTECTION Mode
after about half Hour of using a Pioneer Equalizer
thru its PRE-OUT MAIN IN Channel. What part should I replace to correct the Amp into operation again ?

Thank you very much for any assistance rendered.

Sounds like a Overload. Unplug it, let it sit for awhile. If it comes back to life, your lucky. If not your going to need this.

http://www.hifiengine.com/manuals/sansui/au-517.shtml