What is the "processor" in & Out function on the Marantz PM-68?

You don't see any glass fuses? There is also a non replaceable fuse in the power transformer.

It shut down probably due to overload. Did you let it cool and turn it back on at a lower volume level?

Take it to a repair shop...you are about to have a failure.

Hi mas_66,
Make sure that the fuse is the same rating with the old one.
If still symptom persist, I've suspected that your output IC is shorted.
You may hang this IC, then power up the unit.
Observe what will happen, if this cure the symptom then this is a clear indication that this IC is shorted and made the fuse blown while it is in the circuit board.
Hope I helped you.
Have a nice day!
Thanks for using Fixya.

The easiest thing to do would be to put high wattage level controls at your speakers
Parts express sell them and MCM electronics

Contact Marantz support direct..Check their site

double up the speaker and then use the two extra screw to hook sub and center

Sounds like your left channel output transistors are getting weak.

try turning the system on with no speakers hooked up. and see if it clicks off. if it does,the problem may be the a short on the speaker connections.

look on the back of the TV and there should be L/R audio outputs (white & red), connect this to a spare input of your amp via a connecting lead eg. AUX or any other input except PHONO.

hope this helps.