I've just sold a 1984 to 1989 DCC (Saab part no. 91-24-579) on eBay & the buyer says it is dead. Does a DCC have an internal fuse? His original unit went blank & doesn't work in his friends' car & neither does the one I sold him. His friends DCC works in his car - so the wiring must be ok. Even the display lights don't light up - which seems odd to me. I bought the DCC off eBay myself before I found that I needed a much later unit for my '97 9000. Any ideas?