Grundig YB400 -- No Reverse-Polarity Protection ?

I did something careless (stupid) and plugged the wrong AC adapter into my Yacht Boy 400 shortwave radio. The voltage was right, but the polarity of the plug wasn't, and now it's dead. The digital display, station memory,and tuner still seem to work, but there's no sound. I've made this mistake before with other devices, with no harm done. So does anyone know, does the YB 400 not have reverse-polarity protection? Also, does anyone familiar with this set have clues as to what it was I fried? Thanks in advance ...