Stereo connections to 12v system

[jaschrumpf]

My boat came with a 4-channel stereo/cd player that wasn't hooked up, and no manual either. The PO had wired everything to one speaker and that was good enough for him. I've been trying to get it set up right, but I'm running into some strange problems.

My speakers are very basic 6" paper cones, and there are only two of them mounted on the cabin bulkhead. The wires run to where the batteries are kept under the main cabin settee, and are marked with a black stripe to signify the ground for the speaker.

The wires from the tuner are a hot red and ground black, and green and grey wires that (I presume) carry the front and back channels. This is the setup I'm using: the ground wires from the speakers are spliced together and connected to the battery negative terminal, and the positive leads form the speakers are connected to the leads from one color of wire from the tuner -- in this case, the green wire.

However, I'm getting some very strange behavior from the system. When I connect the two ground leads from the speakers to each other, I get sound from the speakers. Yet neither speaker is connected to ground, only to each other, and both are mounted to a teak bulkhead. When I connect them to the negative battery terminal I get much better sound quality -- but here's the weird part: if I turn the radio off and back on again, the speakers don't work. However, if I disconnect the main negative lead from the battery and reconnect it, the speakers start working again.

It's got nothing to do with the radio: its light comes right on every time. It's just the speakers that refuse their duty unless I disconnect them from the negative lead and reconnect them.

If anybody has an explanation for that behavior, I'd love to hear it.

Thanks!

[Gary1]

Just a thought. If the previous owner was only running one speaker on a system that was designed for four, it's not inconceivable that the final power amps are blown in the radio.

Most car stereos use direct coupling of the final--in other words straight off the power transistors. These have to have a load on them (either 4 or 8 ohms from the speaker). If they don't have a load, they overheat and go away.

As to the wiring color codes, talk to an installer at Sight-n-sound, Rollin' Stereo, Pep Boys, or someplace like that. If you tell them the make and model of the stereo, they can probably rattle off the color codes to you. Some of it is standardized now. I think green is the automatic antenna control and yellow is for the clock/channel memory, but I wouldn't swear to it. The radio itself will almost always have a red and black lead. These hook to +12VDC (red) and ground (black). Most times the speakers are run in pairs, too, but the color codes change from mfgr to mfgr.

good luck

[sailingdog]

Most recent stereos use a standardized color coding for the wires, which was developed by the CEA IIRC.

Yellow: battery power
Red: accessory (key-switched) power
Black: ground
Blue/white: remote amp turn-on
Blue: power antenna
Light Blue: Mute
Orange/white: illumination

Speakers:
Left front: white
Right front: gray
Left rear: green
Right rear: violet

Solid color speaker wires are positive; black stripe is negative

[camaraderie]

What brand and/or model is the radio? Gary is correct about the possibility of the output transistors being blown but you said you are getting some sound so it is worth trying to scope it out. Dawg is right about the harness now being pretty standardized but that varies on the speaker wire side a bit and of course, it could be an older radio. I would first get rid of any speaker ground to the battery and just run the single ground from the radio with all speaker positives and negatives being run to the radio. If the colors you have match what dawg has listed, run the white and white striped wire and gray and grey striped wires to the speakers and tape off the other two. Otherwise....provide brand and or model and we may be able to help sort it out. Do NOT turn on the radio without the speaker wires being hooked up!
BTW...if it doesn't work out..sailnet just sent out an ad on a BOSS CD player with audio input jacks (i-pod etc.) for 60 bucks and that is a nice deal.

[Karletto]

yup ground is black, red is to turn it on with the key, brown is for cd changer (?) and yellow is constant -> to turn it on with on-off radio button. so choose red or yellow to bring power to your radio. wires for car speakers have different colors with white strip around.
i usually install radios on red couse on yellow it can happen that you turn the volume down and forget. than you leave with the radio still on so it can uncharge your battery.

[sailingdog]

The yellow line is usually a very low amperage line for the stereo memory and clock. Red is generally the high amperage power line.