Audio Systems: 92 chevy delco radio problem, delco radio, accelerator pedal

Question
A friend has a 92 chevy truck and the 3 piece radio quit working. Not sure why. I'm an electronic tech by trade and gave it a look. The control unit has 12v at the input harness on the piggy back board. I followed the 12v path past the harness and it is on the card. No voltage at any ICs or components. Pushing the power switch on/off has no effect. Any ideas where to begin? Thanks Steve.

Answer
ok the amplifier tuner pack close to the accelerator pedal is the most important unit   there needs to be 2 power 12 volts
one always on constant  and the other on only when the key is on the ignition

check both fuse box one fuse is mark radio the other is backup
or batt   if they are ok and you have 2 powers  
the amplifier is defective,    small square unit on top near ac controls never goes bad
the eq tape  goes bad but you only lose audio
the unit on top needs to show at least the time if not there is no power

good luck