I gave my son a SX 750 for his turntable. He has noticed that it cuts out while the other sections (AUX for CDs, etc.) seem OK. What's the problem and the solution?

If it is cutting out completely, all I can think of is a dirty selector switch. Have the controls been cleaned recently?

It probably ISN'T the power supply, the phono power is shared with the control amp and tone controls, and is derived from the 33v and -33v supplies, dropped with a pair of resistors and zener diodes.

Phono loss would be accompanied by audio loss even in Aux.

Tone defeat would not eliminate this effect.

Loss of the +/- 33v that supplies the resistors would affect the power amps too.

The only thing left is the switches need cleaning. Interesting in that it is both channels, but IF the receiver wasn't switched to phono for years, the corrosion could have built up significantly on the phono section of the contacts.t