Bad audio out ports?

[AJM511 10+ year member]

I have a pretty old sony head unit. its says explod 50watt x 4 on the front. I hooked up my amp and sub, but i get no sound to the sub. the amp powers on and everything, but no sound. im wondering if it is a bad audio out terminal on the radio? how can i test this?

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[subzero 5,000+ posts]

There is a internal selector. power the deck down and the puch the volume knob in and hold for 5 seconds. the you will see the menu....