low voltage to radio?

[Will Ng]

At 03:17 PM 1/7/2005, Andy Schor wrote:
>My aftermarket Blaupunkt radio sometimes won't play when turned on.  The
>lights light up and it cycles through all of the functions on the screen
>(without being prompted) while the faceplate is attached and the unit is
>turned off.  When I press the power button, it lights up but there is no
>output (sound).  The CD player shows the track and time displays, still no
>sound.  The red power lead is connected to the relay panel
>up under the dash (behind knee bolster), the yellow lead is connected to
>the yellow in the harness.
>I'm not an electrical engineer, but is it possible that there's enough
>juice to turn the unit on, but not enough to power it?
>Something else?
>
>Andy Schor
>'91 200q20v Avant


Check you grounds. The GND wire from the radio may be loose or not grounded 
to a good source.
The radio may be getting a poor ground from the antenna lead's shielding.

Most modern 'high powered' stereo head units use the constant +12V input to 
not only preserve clock and station memory functions, but can be part of 
the tuner's power circuit.
True of Concord stereos of old.
Some high end head units are wired like amplifiers. The high amperage +12V 
input is a constant, and the on/off by ignition switch is served by a 
switched +12V input. True of current Eclipse models.

HTH,
Will
1990 200q PITA