New Alternator - No AM Radio

["Fred L. DeRoos" <flderoos@mmmpcc.org>]

Date: Sat, 17 Jan 1998 18:10:43 EST
From: Boomsday <Boomsday@aol.com>
Subject: Re: New alternator - No AM radio?

>Don't see any connection with the alternator change out, but my >experience
>with radio reception is that even the smallest break in
>antenna/cable/connector continuity will destroy AM reception but FM >will
>"jump" this incontinuity. The only other thing I can think of is the >new
>alternator is generating too much RF interference (which happens to >also mess
>up AM reception). Did you try listening to AM with the engine not >running?
>That would eliminate at least one possibility.
>Rich

If AM reception is OK wtih the engine not running (as suggested by
Rich), look at the back of the alternator and see if they forgot to
put the supressor (either a standard capacitor or a coaxial capacitor)
back on the new alternator.  This happened to me and I had the same
symptoms, although I could still receive strong local AM stations.  

Also I forgot which car you have.  The 200's with the Bose system
(possibly /probably others) use diversity reception. The front and rear
in-window antennas (antennae) are used for FM, while AM is received
using only the back in-window antenna.  I had a lot of computer noise on
AM from all of the computers in the car.  You could hear them on AM if
you just turned the key on without starting the engine.  I traced the
problem to a poor ground at the rear amplifier.  No AM reception is
acceptable, but not as good as with an external antenna.

Another possibility, but I doubt if this will correct the problem.  You
can try disconnecting power to the radio again (go to SAFE mode) and
then reenter the code. Strange things can happen to synthesizers
sometimes. 

Good Luck,

Fred L. DeRoos