I have a Panasonic CD Stereo Shelf System, Model SC-PM19. When I am playing a CD, after a few minutes the entire units shuts off and "F61" flashes for a moment on the screen before total shutdown. I first thought it might be a problem with the system's timer (which I have never used), that maybe I inadvertently switched it on. But I have followed the instruction manual directions for canceling the timer and it does not seem to solve this problem. Any ideas?

F61 is generally a 'shorted-speaker' or 'microprocessor' problem.

Generally speaking, an amp protects itself from heat, shorts and overloads.

Overloads can be from excessive periods of high output and shorts would be wiring issues or a speaker blowing up.

You should be able to feel if it's hot. WHY is it overheating? Make sure it has sufficient ventilation on all sides and that vent holes are not blocked by dust balls. Ensure the fan (if equipped) is running as designed (some only operate on demand). Clean dust and debris from it.

If the amp comes back on after cooling, you're lucky. They only have so many self-protection cycles in their lives so continuously resetting or cycling their power without addressing the cause can do more harm than good.

If it protects immediately on a cool power up you should disconnect the speaker connections and try it 'naked'. If it comes up then diagnose which lead(s) are shorted. If it does not come up the problem is internal and should be left to an experienced hands-on tech.