The simplest way to trouble shoot is to swap the speaker connections at the back of the amplifier. If the problem follows the speaker than a connection, possibly internal to the speaker fails as the speaker warms up(voice coil).
If this swap indicates that the amplifier is the problem swap the channel inputs to confirm that it is internal to the amplifier. Also try a different source to confirm it is not the output of the source.
If not, than the amplifier would appear to have a problem. This would most likely require a qualified technician to repair.
Tthese amps are robust and you may have to choose an alternative speaker pair(example sub-room or speaker set 2) to maintain the set up you have. Also a internally shorted speaker may have the impedance low forcing an output protection feature.
Martynas ZCS4228A on DSP board can be overdriven on the inputsCS4228A on DSP board can have shorted loads on the outputCheck also the board (might be burnt also)Here is block diagram for you:Check components around it thoroughly.Let us know how you make it out.
Not having the ability to look at it on the bench, more than likely your DSP chip is bad. If you have a local repair house that is willing to confirm that is the problem without charging you an arm and a leg, that's your best bet. It is an expensive repair, anywhere between 300 to 500. At that point, I would say to replace the unit. Sorry for the bad news, but that's my "best guess" The only other thing to check would be your "Audio input Settings" Make sure it's either on "Auto" or whichever type you are using. "Digital Coaxial", "Optical", or "Analog" (RCA) hope this helps! If you have any further questions, just post a reply and I can help further. Best of luck!
Marantz SR 5200/6200 lost audio or crackling on left or right channel except in mode s-direct is now fixed !The root cause is a defective inegrated circuit on DSP board (the one with digital inputs). To fix it change the chip CS4391 by a new one or better by the improved version CS4392. On my device a capacitor was cut close to this IC : replace one 1uF after changing the IC. For any question search me with my callsing "F5RCT"; i have a spare IC for the one who is able to change it !I'm amateur radio and engineer