Hands Free Phone Mute Question

[JMotz]

I'm trying to find out information about the phone mute voltages. I've read most of the posts for connecting the mute wire from a hands free kit to pin 10 of connector block A on the back of a head unit. Also in the post's I've read the voltage is +12 when the H/F unit is not in use and 0 volts when the H/F is in use. I've measured the voltage on my H/F mute wire it's about 11.5 volts when not in use and 3.5 Volts when in use. I can't get the radio to mute. I'm wondering if the +3.5 volts is the problem or if someone measured the voltage on their mute wire and if so what were the voltages.

My only other guess is that I cooked the pin, because I soldered a wire directly to pin 10 and pulled it through the stock connector block.

Thanks
Jon M.

[monsta]

Originally posted by GaryM in this thread

Quote:

Yeah, I've used dashmount stuff before but I like the phone close to my hands and my eyes near the windscreen so this why I chose this location. As for the phone hook up. I think you will find that the mute lead on your phone kit goes low (0V) when the phone is in use.

Assuming you have a Boost radio, effectively there are three individual connector blocks on the rear housed in one big shell. The one with the power and speaker connections and another with the low level audio for the CD changer. Your phone mute lead needs to be connected to pin 10 of big connector. Looking at the rear of the radio this is the blank position underneath a thin White/Red/Yellow lead. With this connected the head unit should mute during calls. Unfortunatly though it still will not say "phone". This only comes up when the head unit is ready to accept an external audio input from the phone. This is triggered by an additional line and guess what this time it is active high (+12V = triggered). So this is where I needed to build a little interface to also give me the +12 for pin 11 on the head unit (blank position below the mute line and above the thick Brown lead).

With this now done when the phone is in use it will mute the head unit and say "phone" on it. If you want to get more adventurous you can lose the speaker that comes with the car kit and connect the signal direct to the radio. To do this you need to wire the speaker output from the phone to the smaller connector on the radio. For units without satNav this will not have a connector shell and is the small bank of pins in the bottom R/H corner. Pin 6 (top right pin)= signal, Pin 12 (bottom right pin) = signal ground.

Have fun

[JMotz]

If this quote is right then my connection should at least mute the phone. I am connected to pin 10. Do you think it's the +3.5 Volts when the phone is in use. Instead of 0 Volts. If I'm reading the quote right and according to other posts that I've read I should at least get the head unit to mute.

Thanks
Jon

[monsta]

I think it needs to be on dead 0v

Does your hands free have a switched 12v supply as well? I.e. when the phone rings does it go to 0v and 12v when not in use? I used that on mine until I discovered the mute connection. It just turned the radio off when the phone rang.

[JMotz]

My kit only has the one wire going from 11.5 Volts when not in use to 3.5 Volts when in use. Thanks for the information. I'm wondering if I should try wiring the head-unit's switched power to the mute wire and see if the low voltage will switch it off. Well it's not so bad to turn down the volume, I'll probably just live with that for now.

Thanks
Jon

[mikeythemini]

Sometimes when I have fitted to bmw's they won't even mute without the extra live.
But that said 3.5v sounds wrong, what kit are you using??

[JMotz]

The kit I'm using is the new Sony Ericcson HCB-30 Bluetooth hands free kit. I measured the voltage with my cheapo Volt meter. Other than this the kit is working fine. The manual that came with the kit is a piece of junk. It has no specs at all. I looked around online but I can't find any other information. The kit has only been out I think since late november so there doesn't seem to be much information out there yet. If you hear anything about this kit let me know. Like I mentioned in a previous post it's not that big of a deal to turn down my stereo but it would be cool if the mute worked.

Jon

[moonshine]

I got my 6310i handsfree fitted yesterday, and got it interface with my boost tape unit.

The phone mutes the stereo, plays thru the stereo speakers but the head unit doesn't say "PHONE" - any ideas??

GErry

[zoooooom]

Quote:

Originally posted by moonshine
I got my 6310i handsfree fitted yesterday, and got it interface with my boost tape unit.

The phone mutes the stereo, plays thru the stereo speakers but the head unit doesn't say "PHONE" - any ideas??

GErry

Yes I have some Ideas

Idea no1 you went to the wrong place to get it fitted

2,Bright idea,will kick your ass on Sunday

3,The stereo has been muted with an interface and the mute wire to the head unit has not been connected,this does not effect the operation just that it does not change the display To cure this problem refer to Idea No1

[moonshine]

Hi john.....

re
idea no 1 -

i know, but my boss had already paid for it for me.. otherwise i'd be in aberdeen like a flash,


sunday?? - aberdeen social? i'll have to check my diary (i gotta move house this weekend or next!) kik my ass....not likely!!!

see u later,


g

[GaryM]

moonshine, did you fit your interface or is it an aftermarket adapter like Autoleads? It sounds like the latter to me.

These aftermarket adapters are generic in design to allow fitment to many different HU's. They really don't interact with the HU at all. Instead they work by using a relay to effectivley disconnect the speakers from the HU and connect them to the HF kit. This means lots of wires & cuts into your HU wiring loom.

If you go the route of wiring your HF kit direct to the HU as JMotz is trying to do then the wiring is fairly simple and you will get the message on the HU.

JMotz, When I did all the testing and exploration of this I never really checked the voltages. The simple check to test that the HU is still OK is just to ground pin. If I get chance I'll check my notes when I get home. It does sound as if the logic levels from your phone don't match the levels required by the HU. This will mean a little converter circuit. Hence why people go the Autoleads route. But it can still be done.

[GaryM]

Well I've checked my notes and I did not note the voltages. If you have managed to test the HU by spimply taking pin 10 to ground and it worked then it would appear to be a issue with the logic levels. How up are you for a little simple electroinics? It may well be that with few simple components I can provide a solution. Over to you JMotz

[mikeythemini]

On boost as well as the mute wire which the phone must ground to mute the radio, you must add a permanent live to another pin, for it to say phone in the screen. Will look up pin numbers at work.
Or use a soundlinx ericsson to mini interface
mike

[GaryM]

Sorry Mike but this was not so in my case or the research I've done on my Boost HU.

For the radio to mute and the display to say "PHONE" pin 10 needs to go low (0V). Thats all

The other pin, pin 11 is used to active the speaker level input on the HU and power it up. Hence this needs +12V during a call or while the phone is switched on. And of course you will need to wire the speaker output of the HF to the telephone input on sub connector CB891-C pins 6(TEL+) & 12(TEL -). This is the one that you can leave live but not when the key is removed as you will risk the battery being flatened over long periods. The reason is that the +12V is used to power up in the front amplifier in the HU even if the HU is switched off. Otherwise you HF output would not be heard unless you had the HU on.

Hope this clears things up.

As you suggest Mike an aftermarket adaptor might be easier in this case.

[monsta]

He's right, thanks to GaryM I got my Nokia kit to say 'phone'