[urq] radio problem

[urq@pacbell.net]

Back in the days when cars were started with keys, in the US & other parts of the world the ignition switch had an "accessory" position where it was possible to turn on the radio. When the key was fully off the radio would not operate.  Radios designed for these cars assumed that the ignition switch would cut power that would otherwise drain the battery.

I doubt that cars were designed with direct power to the radio to minimize alternator/ignition noise; this can be a PITA on aftermarket stereo, but is easily dealt with by the manufacturer.  I consider it to be more philosophical than anything else.

Alternator noise isn't always due to bad diodes, IME it isn't that common at all.  Alternator noise I've dealt with is due to separate amplifiers, and most likely due to voltages induced in the ground circuit from current pulses due to the unfiltered alternator output.

Steve Buchholz

----- Reply message -----
From: "Patrick Carlier" <p.carlier at pandora.be>
Date: Sun, May 30, 2010 11:06 pm
Subject: [urq] radio problem
To: <urq at audifans.com>

It's not unusual that a radio is powered directly from the battery .
Most of the time it's done to reduce or eliminate alternator noise .
If that's the case , I suspect there's a fuse somewhere in the wire
most likely  close to the battery .

Btw , the cure for alternator noise is not to change the wiring or add 
filters and
capacitors , but to check and fix the rectifier diodes in the alternator .
Corroded ground connectons are also notorious for noise in the radio .

Pat






----- Original Message ----- 
From: "Keith Lloyd" <spotatashleys at hotmail.com>
To: <urq at audifans.com>
Sent: Sunday, May 30, 2010 10:26 PM
Subject: [urq] radio problem


> OK, I've done somethng silly and now can't see the wood for the trees.
> My Blaupunkt CD player was playing up and so I decided to change it for a 
> Sony. Silly me plugged in to the sony via the bunch of leads already 
> attached to it. It worked briefly and then nothing. The unit still works 
> because if I find a fresh permanet live (cigarette lighter) and a 
> suitablle earth it fires up. However, the original live feed is now dead. 
> Why I don't know. Does anyone know where the red wires come from? There 
> are no blown fuses in the fusebox. Does the permanent live for the radio 
> come from somewhere else with it's own fuse? If so where?
> I'm really puzzled and very tired so not thinking straight, I have not 
> noticed anything else not working which would be a clue.
> Any assistance gratefully recieved as usual.
> Many thanks
>
> Keith
>
> '87 WR
>
> p.s. just to confirm - I only need 4 wires to the radio right? permanent 
> live, earth, illumination and feed to electric aerial.
> The autocheck has it's own separate speaker on my car so no feed to NF on 
> radio.
> Cheers
>
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