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head unit trouble, has me stumped!

Discussion in 'Motors' started by henleyryan, 11 Jul 2006.

  1. henleyryan


    Joined: 4 Oct 2004

    Posts: 227

    Location: Northants

    I have an old sony one in the car at the moment and it recently stopped working, the sound only came out of three of the four speakers and it constantly says"offset" which the book says is an internal error.

    I now have a JVC one to replace it but no sound comes out of it whatsoever. IT powers up and is playing the CD but no sound at all.

    I plug the sony back in and voila... sound again.

    I thought the JVC one was broken so i have now tried it in three other cars and it works PERFECT. Move it back into mine and no sound again.

    I have now tried a Pioneer and two sonys in my car and they all work fine in mine and other cars.

    The jvc works fine in everyone elses car except mine?!?!?!?!?

    The connector is standard ISO so i can't be doing anything wrong there, especially as it works when connected to an ISO connector in other cars.

    Would be really greatful for anything on this one please.

  2. Gribs

    Wise Guy

    Joined: 12 Nov 2003

    Posts: 2,342

    Location: Skipton

    As it doesn't work it suggest that the connector isn't wired up as a standard iso connector. Have you checked it to see if it is?
  3. henleyryan


    Joined: 4 Oct 2004

    Posts: 227

    Location: Northants

    i haven't checked the wiring diagram, the JVC one doesn't have a connector that can be modified, it's an ISO socket actually on/in the unit itself. All the other head units work in both cars which indicates the wiring is the same in both cars, the JVC works in other cars but not mine, again using a standard ISO connector in the other cars.

    I thought it might be telephone mute cable not being grounded but apparently the system mutes when it IS grounded and makes noise when the TM cable ISN'T grounded.

    I'm going to try running it straight off the battery with only one speaker to see what happens.
  4. lordrobs


    Joined: 30 Sep 2003

    Posts: 14,998

    Location: Norwich

    I'd guess that the speaker wire on the non working speaker has split and is shorting out on the bodywork. On some HU's this will cause all sound to be muted.

    Bit of a PITA but worth checking the cabling as your next step.
  5. henleyryan


    Joined: 4 Oct 2004

    Posts: 227

    Location: Northants

    Latest news for anyone interested:

    I ran it with just a single speaker attached and it turned on and worked, Great!

    Plugged the ISO speaker connector in and there was sound out of all four speakers, no idea what was going on but at least it worked now. Turn it off and back on and the sound was gone again!

    If the unit was turned on then the speaker connector was attached then it worked, if the the speaker connector was attached before the unit was turned on then there would be no sound until the connector was disconnected then re-connected. Mighty strange in my opinion but what the hell.