Re: Wiring

[dan_masi@MENTORG.COM (Dan Masi)]

On Oct 15, 11:28am, Jay@aol.com wrote:
> Subject: Re: Wiring
> In a message dated 96-10-15 11:14:41 EDT, APOWELL@agcom.tamu.edu
(Al Powell)
> writes:
>
> > > Top section: What is U(B)+?
> >
> >  I think it's (unswitched Battery +) but this is a guess.
> > Check with  a voltmeter for 12v present at all times.

I'm guessing this is not the case... there's already a
"main power" input as well as a "switched" input.  If I
had to guess on this one, I'd say it might be a battery
backup for station memory, or something like that.
If you check it with a voltmeter, check it without the
radio connected.

> >  Data is the feed to the little window in the dash which shows
the
> >  radio station.  Clock is a poser....I don't know, unless power
> >  for the clock loops through here, which I doubt.
>
> Actually, most serial bus architectures have a "clock" signal
>which pulses to tell you when to read each bit off the "data" line..

Right.  Again, I'm guessing it's an RDS accessory, that can
safely be ignored.


> >  > What is Com?
> >
> >  Ground or Earth, as the Brits have it.
>
> Weird.  They labeled every other ground with the standard symbol.

Warning!  Do NOT just ground this.  As you pointed out, other
pins have been labelled "ground".  In this context, "COM" likely
means "common", which would be the common or "shield" part of
the line outs.  On many radios, this will also be ground,
but don't count on it.

> >  *Power (Audis have no switched power - all are unswitched.)
>
> I think this is untrue for the 96 A4Q

It is indeed untrue.  The A4Q radio shuts off when you pull the
key out of the ignition; but you can turn it back on by turning
the power "off" and then "on" again.  So the main power to
the radio is continuous, and the radio uses switched power as
an input to play games with.

> >  *Antenna (amplifier) relay must be connected, even tho you
> > have no power antenna - it powers up the Audi antenna amps.
>
> Ah, I would never have known that.  Thanks.

Does the A4 have an antenna amp?  I thought it was amp-less.
In any case, I think it's a good bet that the wire of
interest in this case might be the one marked "SW" in
the "Line Out" section, though this is just a guess.
The rear speaker amp must be turned on by one of the
signals here, and if there is an antenna amp, it's probably
wired to the same turn-on signal.  So all you have to do
is find which wire is the turn-on (use a voltmeter and find the
wire that goes to +12V when you turn on the radio... it's
gotta be either "SW", "Ub+", or S-Kont, I think everything
else is explained).  When you find the turn on signal,
connect your Sony's amp turn-on output (usually a blue wire)
to it.

Dan Masi
'96 A4Q