S80 Amplified Stereo & Handfree Issue

[Michaelw]

Hi all.

Apologies for my first post being a technical question, but i would really appreciate some help please.

I have a 2003 S80 D5 with the Pro Logic stereo with the amplifier under the driver’s seat. I have fit a handsfree kit today by using a SOT043 harness connected at the amplifier end and then i ran cables up to the back of the stereo to wire in the two live feeds and the earth. My problem is that the minute i turn the ignition on i get terrible interference through the speakers which gets louder with the stereo volume. However, if i try and make a call it cuts the stereo like it should and the phone comes through the front speakers with no interference. If I start moving around the live cables i can get the interference tone to change but i have checked the connections are good and not getting trapped anywhere.

Has anybody come across anything similar in the past? Do i need some sort of device to stop the interference?

Any help would be gratefully received.

Many thanks,

Michael

[Missing Lincs]

Hello Michael

I can't quite follow where you've made connections?

The SOT adaptor fits behind the radio, but instead of the grey speaker plug connecting to the speaker connector on the radio it plugs into the return lead from the amplifier (two grey connectors joined to each other that could be tucked away).

[Michaelw]

Originally Posted by Missing Lincs

Hello Michael

I can't quite follow where you've made connections?

The SOT adaptor fits behind the radio, but instead of the grey speaker plug connecting to the speaker connector on the radio it plugs into the return lead from the amplifier (two grey connectors joined to each other that could be tucked away).

Thanks, that could be my problem. I only saw the green plug on the back of the stereo so I disconnected the speaker plug from the amp under the driver's seat and connected the grey harness there. Would it make a difference though just connecting at the amp instead of behind the dashboard? They are still the same wires unless it's picking up interference from the powered side of the amp. I can connect it all at the amp and everything is fine, it's only when I plug in the handfree module that the interference starts.

Thanks,

Michael

[Missing Lincs]

Originally Posted by Michaelw

Would it make a difference though just connecting at the amp instead of behind the dashboard?

In theory as the speaker wires are a high level signal, it shouldn't make any difference where you connect into the speaker wiring.

What I'm thinking is that you must have extended the wiring from the green connector back to the radio?

You could have created an earth loop, or a wire is acting like an aerial.

I would try the SOT adaptor at the back of the radio with no extra leads and go from there.

[Michaelw]

Originally Posted by Missing Lincs

In theory as the speaker wires are a high level signal, it shouldn't make any difference where you connect into the speaker wiring.

What I'm thinking is that you must have extended the wiring from the green connector back to the radio?

You could have created an earth loop, or a wire is acting like an aerial.

I would try the SOT adaptor at the back of the radio with no extra leads and go from there.

I’ve now re-wired it and connected everything behind the dashboard. I’m still getting a little interference, but its not as bad as it was. The strange thing is that the interference comes through the speakers even with the stereo turned off. With the stereo on you can increase the volume enough to drown out the interference noise. I’d still like to know what it is though as it is rather annoying.

Thanks,

Michael

[Missing Lincs]

You seem to be going in the right direction.

Most hands free units have there own amplifier to drive the speakers, hence the box that goes into the speaker wires. It contains relays to disconnect the cars amplifier and then connects its own signal to the speakers.

It is strange that you are getting noise all the time. I wonder if you have a duff hands-free kit?

What make/model is the hands-free?

[Michaelw]

Originally Posted by Missing Lincs

You seem to be going in the right direction.

Most hands free units have there own amplifier to drive the speakers, hence the box that goes into the speaker wires. It contains relays to disconnect the cars amplifier and then connects its own signal to the speakers.

It is strange that you are getting noise all the time. I wonder if you have a duff hands-free kit?

What make/model is the hands-free?

I haven’t got a box that goes in tot he speaker wires, unless you mean the handsfree kit box?

The handsfree kit is a Novero (i’ve Had one before and that was very good)

[Missing Lincs]

Originally Posted by Michaelw

I haven’t got a box that goes in tot he speaker wires, unless you mean the handsfree kit box?

Yes, that's the part I was meaning. You have a noise that has started since you connected the hands free kit, it's all the time regardless of if the radio is on or off. To me that suggests the part you've plugged in - the hands free box - looks a likely source of the noise.

[Michaelw]

Originally Posted by Missing Lincs

Yes, that's the part I was meaning. You have a noise that has started since you connected the hands free kit, it's all the time regardless of if the radio is on or off. To me that suggests the part you've plugged in - the hands free box - looks a likely source of the noise.

Hi. Well the noise now seems to have almost disappeared but now i have another problem. I think the amp is cutting the speakers out for the radio once the radio has been on for any length of time. It took me two hours this morning to get to work and for the first hour it was fine, but then the sound keep cutting out for a minute of so at a time. Could this be the amp overheating and is this something you have previously come across?

Thanks,

Michael

[Missing Lincs]

To me it's all too much of a coincidence that you installed something new and now there are problems with things that have worked fine for years.

The only other thing I can suggest is that you may have disturbed another connector on the radio wiring. There is a lead which feeds a low level signal from the radio to the under-seat amplifier.

Other than that I think you're looking at a faulty hands free kit.

The way to say for certain is to remove the hands free and the SOT lead, if all is well, plug the SOT lead in, but not with the hands free connected, just join the ISO speaker leads on the SOT lead to each other. Finally plug the hands free in again. With the cut-out issue you'll need to try each option for a couple of hours.