Audio Systems: 91 Silverado Radio, cassette tape player, channel equalizer

Question
The radio in my 1991 silverado truck is misbehaving. When turned off the clock shows 10:30 and does not change. When turned on it shows one radio station on the display but no sound and no other controls work, although the indicators do come on. Example Scan, Seek, volume and balance appear on the display when pushed but they do not function.
The truck came with a four channel equalizer and a cassette tape player mounted in the center of the dash. Any hope, suggestions?

Answer
there is a small brain unit  rectangular about 9x4 it is under the dash by the accelerator pedal there is 4 plugs in to the box

this box is the radio tuner brain and it needs to be repair or replace  

you can get one from www.oemautosound.com for about $ 80.00