Car Stereos: 1997 Ford Conversion van radio has no sound, ford conversion van, ford conversion vans

Question
I have a 1997 Ford Conversion van that says it's a Waldoch version or something like that.  My radio was working fine and then I went to go to work one morning and there is no sound.  I can change channels, keeps time, etc.. everything works except the sound.  It is the factory radio and I even found another exact replacement radio and tried it, no sound.  Is there an external amp in these Ford Conversion vans and if so, where are they located?  I can not think of any other reason the sound just stopped working since I have tried 2 of the same radios now.  If you have any ideas, I would greatly appreciate it because I am lost.  Thanks in advance.

Answer
Jason, There usually is not any external amps, but the speaker wiring is upgraded by the conversion company.  Chances are that one of the conversion speaker wires has gotten a bare spot wore on it somewhere and it is shorting out the system.  You need to find the shorting wire, before trying another radio.  Hope this helps, Scott