Wiring up a new radio in an old car.

[wculbert]

Hi,

I have a 1987 Morgan 4/4. I have bought a Clarlon Radio for it whic has a remote control and wish to fit it.

However it has a selection of different connections at the back of it and do not know which one to use in the Morgan. Which ones goes to what?



Anyone any idea.

Thanks,
William

[Pigeon]

Can't see the picture. The site you've hosted it on is being an arse.

[slammedvanman]

Without seeing the picture it's difficult to say? I'm no auto electrician but have fitted a few radios to classics. I usually run a separate live feed directly from the battery (with an in-line fuse as close to the battery as possible) to the head unit and then find a suitable earth point under the dashboard. The wiring colours are usually:
Red - positive feed
Yellow - positive feed
Black - earth
Blue/white - remote (not needed unless you have an electric aerial or external amplifier)

The red & yellow can both be connected to the live feed you've run from the battery (I believe one is for powering the unit when switched on, the other is for continuous power to maintain radio station pre-sets, security codes etc).

Your speaker connections are then usually in colour coded pairs i.e. green and green/black. One is positive the other negative but I can never remember which (if you get them the wrong way round the speaker will sound awful).

As I said I'm no expert and take no responsibility for damage () but no-one else seems to be responding? Any auto-electricians out there?

[Pigeon]

slammedvanman said:

The wiring colours are usually:
Red - positive feed
Yellow - positive feed
Black - earth

Those are the colours coming out of the stereo. But there is a colour coding "gotcha" to watch out for with the wiring of the car. I don't know whether it would apply to a 1987 Morgan, but it certainly applies to a 1987 Ford...

You'll find two convenient power feed wires, one positive and one negative. The colours on them are brown and black. Now, you'd naturally guess that brown is positive, and black is negative, wouldn't you? Course you would.

Unfortunately, whoever designed the colour code is so unbelievably stupid that I cannot imagine how they ever got a technical job, or indeed any job more intellectually taxing than shovelling shit. Brown is NEGATIVE and black is POSITIVE.

And it is made worse by the similar levels of stupidity displayed by the designers of stereos when it comes to reverse polarity protection. Schottky diode in series with the positive feeds? No, that would be too sensible a method. The protection is a reverse shunt diode. So when you connect the stereo up according to what you quite naturally think the colour coding is, the diode melts into a short-circuit blob, then the PCB in the stereo catches fire, then if you're lucky the fuse (fitted to the stereo by the manufacturer) blows.

Some "designers" really do need to be put up against the wall and shot.

[jith]

Pigeon said:

slammedvanman said:

The wiring colours are usually:
Red - positive feed
Yellow - positive feed
Black - earth

Those are the colours coming out of the stereo. But there is a colour coding "gotcha" to watch out for with the wiring of the car. I don't know whether it would apply to a 1987 Morgan, but it certainly applies to a 1987 Ford...

You'll find two convenient power feed wires, one positive and one negative. The colours on them are brown and black. Now, you'd naturally guess that brown is positive, and black is negative, wouldn't you? Course you would.

Unfortunately, whoever designed the colour code is so unbelievably stupid that I cannot imagine how they ever got a technical job, or indeed any job more intellectually taxing than shovelling shit. Brown is NEGATIVE and black is POSITIVE.

And it is made worse by the similar levels of stupidity displayed by the designers of stereos when it comes to reverse polarity protection. Schottky diode in series with the positive feeds? No, that would be too sensible a method. The protection is a reverse shunt diode. So when you connect the stereo up according to what you quite naturally think the colour coding is, the diode melts into a short-circuit blob, then the PCB in the stereo catches fire, then if you're lucky the fuse (fitted to the stereo by the manufacturer) blows.

Some "designers" really do need to be put up against the wall and shot.

Welcome to the crazy world of the Japanese, Pigeon!

[kevlar]

Can I just add that the Red is normally a permant live feed. And the Yellow is a switched live feed. Basically meaning that when you turn your ignition on the radio will come on with it and vice versa. Saves having a flat battery if leave it on all night!

Red = Powers the radio when in use
Yellow = Powers the clock, memory etc. when unit swtiched off.

Not sure where you'd find a swtiched live on your Morgan but I always check the Cigarette lighter first. A multimeter is a cheap and worthwhile investment for anyone with car wiring getting on for 20 years old.

As for watching things melt due to dodgy colour coding - Simple rules, don't plug anything in (power related anyway) until you have checked it with a multimeter or at very least a bulb with a 2 bits of wire, 1 going to any metal part of your car and the other used to test the wires you're identifying. Saves a lot of heartache for the sake of a quid's expense.

Regards,

Kev

[Pigeon]

jith said:

Welcome to the crazy world of the Japanese, Pigeon!

I am fully aware of how they put LSD in the water in Japan but I was thinking of Fords and Vauxhalls... Maybe in Vauxhall's case it's the Opel/Germany connection, since the Germans were already known for lethally insane colour codes (red for earth) on mains wiring...