replacing radio

[Minven Wang <mwang@stern.nyu.edu>]

My radio (on '86 5kcs) went dead last week.  I tried to replace it with a new
digital radio, but couldn't figure out which is the +12v power terminal that
is energized at all time.  The old radio is an offbrand junk that does not
connect to this terminal.  Also I'm not sure about the terminal to the power
antenna relay box.  There are many lose wires under the centre console.  Though
I was an audiophile (and now an audiphile), there is one wire too much to get
the radio working.  Any suggestions?

BTW, while the radio (including the cassette) went completely dead (no sound),
the power antenna is still working.  So I figure that the problem must be
within the radio, not the fuse or power line, and not the speakers (since 
it is rare that all four speakers went dead).  Any comments?

Thanks!

Minven Wang
1986 Audi 5000cs