Sony CDX-GT200 Telephone Mute ATT

[nigelmercier]

I believe my Sony CDX-GT200 has a "Telephone Mute" function on the light blue wire labelled ATT.

Where can I find more information on how to drive this mute function?

[Drumzman]

Hi nigelmercier,

I suppose it depends exactly what information you're after, but there's an installation guide you can download available on the Sony website (link attached) that might help?

http://support.sony-europe.com/Quickjump/default.aspx?site=odw_en_GB&m=CDX-GT200

Usually the wire is connected to a phone car kit that supplies a voltage when the phone rings which makes the stereo sound mute.  The CDX-GT200 definitely has the facility, so it will depend on whether the car installation kit for whatever phone you have has a suitable connection.

Hope this helps.

[nigelmercier]

I'm making the device to mute the stereo myself, so I need to know what voltage to put on the ATT wire. I'm pretty sure it is 0V, but it would be handy to have this confirmed.

[Drumzman · Accepted solution]

Hi nigelmercier,

I believe you're right - it is 0V.  I think that most telephone mute inputs work so that if they're not connected (open circuit) then the GT200 would work as normal, but when the wire is grounded (to the car's chassis) then the telephone mute is activated.  There's a nice easy way to check this and that is to touch the light blue wire to the chassis of the radio (which will be grounded) while the unit's operating - then if the mute kicks in you know that's going to work.

Hope that helps?