Audio Systems: car radio freezes, no buttons work until car is turned off/on again, car cd player, buttons work

Question
I have a Pioneer DEH1200 car cd player (about 2-3 years old).  It recently started freezing randomly when listening to the radio and I cannot do anything when this happens but turn the car off.  No buttons work, even the power, volume, channels, or source buttons.  I do not have any changers or other devices hooked to this.  I checked the fuse on the back of the unit and it was fine, I replaced it anyway but this still randomly happens..any ideas/suggestions?  Thanks

Answer
I think the approach or attack on a thing like this (which, by the way, is one of the most difficult types of problems to diagnose and troubleshoot) is to determine if the problem is internal to the unit or external (such as power wire dropouts).

One way would be to put a volt meter on the main power lead or the ON lead coming from the ignition and monitor it; then when it freezes look down and see if the 12v has dropped or reduced to a low level.

Another thing to do is put the unit on the bench, so to speak, to see if it does it when out of the car.  To do this you must remove the unit.  Hook it up with long wires to the battery (or another car battery that you might have laying around in the garage!) and connect at least one independent speaker to one of the amplifier outputs and let it run for a while to see if it will freeze when out of the car.

If the problem is internal to the radio it will freeze even when out of the car.  If it is external, it will not freeze up out of the car.  

This process of elimination will help you determine what the dickens is going on.

Just replacing the unit will not solve the problem because it the cause is car wiring of some kind the same problem will happen with the new unit.  So, you realy must find out the cause before tackling the solution.

Chances are (my best guess based on your description - and it is just a wild guess because I don't have enough information to make a really intelligent determination) is that it is a voltage regulator to the controller IC chip inside the radio unit.  The regulator is unstable or overheating and when you shut things down it resets and goes back to work.  Repair of something like that is expensive because of labor; big job getting an IC out and soldering in a new one.

Hope this helps some.

Cleggsan