Audio Systems: fm/am reception problem, sony cdx, car antenna

Question
hello, i have a sony cdx-m620 deck.  i had this for around 4 years now.  about a year ago, my am reception completed went away while my fm station was good.  i could turn the volume up all the way and still could hear nothing from the am station.  about a month later, my fm station suddenly went away.  again i can turn the volume up all the way, and just hear static.  i wanted to know in your opinion, is it the am/fm tuner, or my car antenna.  any help on this matter would be very appreciative.  thanks a lot in advance.  

Answer
Chris,
If either AM or FM works the antenna is OK. The problem now is most likely due to a fault with the tuners or with the power switching circuits for the tuners.

Feel free to contact me direct for any additional tech help.

TOM,
T&D ELECTRONICS
tdeser@zoominternet.net