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2005 A170 Radio Replacement wiring

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by Mark1208, Jan 9, 2019.

  1. Mark1208

    Mark1208 Member

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    Hi
    Want to replace Radio 20 in my A Class. Am quite confident about most of it except the aerial amplifier wiring. Have searched internet but no luck but I understand the radio powers the amplifier either via wires or the actual aerial coax??
    Can anyone help as this must have been done hundreds of times but want to make sure that the aerial is powered as normal.

    Thanks
    Mark
     
  2. OP
    Mark1208

    Mark1208 Member

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    Sorry should be audio 20
     
  3. Blobcat

    Blobcat Moderator

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    If your replacement head unit doesn’t have a power output for the antenna you can get an adapter that connects to the antenna connector and your new head unit which then takes power from the head.
     
  4. AnthonyUK

    AnthonyUK Senior Member

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  5. Blobcat

    Blobcat Moderator

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    This is the type of thing you’ll need
     
  6. OP
    Mark1208

    Mark1208 Member

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    Thank you guys, my head unit has a lead that you connect to electric aerial do I connect that to one of these adapters??
    Thanks for all your help
     
  7. Blobcat

    Blobcat Moderator

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    Depends on how it's powered but I'd say yes, but you should check.
    Here's one I did earlier
     
  8. OP
    Mark1208

    Mark1208 Member

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    Thank you so a powered feed when ignition in on is needed to connect it?

    The wire on the head unit is powered when radio is turned on. Is that correct one
    Thanks
     
  9. Blobcat

    Blobcat Moderator

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    You should have a book of words with the new head unit which will show you an ignition feed that you can use for the antenna amp, that is where you should make the connection.
    You will have a permanent live and an ignition feed live going into the head unit from the car wiring as well but I'd use an output from the head unit rather than a supply to it.
     
  10. OP
    Mark1208

    Mark1208 Member

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    You are most kind thank you
     
  11. Blobcat

    Blobcat Moderator

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    Some good info here with pin outs for the ISO connectors. Sometimes they can be slightly different but it's a good starter for 10
     
  12. OP
    Mark1208

    Mark1208 Member

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    Thank you, I have another in-line amplifier adapter that also splits the output to the radio fm and another to dab. It has the same wire to connect to ignition power supply.
    Think this will also do the job??
    Thanks
     
  13. Blobcat

    Blobcat Moderator

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  14. OP
    Mark1208

    Mark1208 Member

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    Sorry to be stupid but all these in line aerial amplifiers need to be fitted to passive aerials? As standard on the original audio 20 radio is the aerial powered by radio?
    When fitting new head is the original aerial no longer powered so it has become passive and the new in line amplifier takes over the role of powering the aerial???

    Am very confused how this works
    Thank you
     
  15. Blobcat

    Blobcat Moderator

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    There is an in-line amp (Mercedes standard fit) which needs power which the Audio 20 supplied. Aftermarket heads don’t always supply power to the antenna connector which is why you need the adapter (which isn’t an amp) which adds the 12v supply so the in-line amp can do it’s job. Without the power the amp won’t work and the radio reception will be very poor.
     
  16. OP
    Mark1208

    Mark1208 Member

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    Thank you again, the unit replacing it has dab and I want to cheat and put a dab splitter that is powered in the same way but says increased the gain to allow the splitter to work and does more than just adding 12v to aerial.

    The fascia kit that I bought comes with everything to fit including little in line unit you mention. Does this mean I cannot connect the dab spitter as it wants a passive aerial or put both the inline splinters one feeding the next?
    Should I completely forget about Dab as I don’t want to fit a separate dab aerial thus I will have to stick with FM.

    Really appreciate your time
    Thanks
     
  17. OP
    Mark1208

    Mark1208 Member

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    I also have a unpowered dab/fm splitter. Could I use this instead with adapter that came with facia fitting kit?
    Sorry again for questions
     
  18. Blobcat

    Blobcat Moderator

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    DAB is completely different frequency and needs it’s own antenna. I’ve used stick on ones in the top left of the screen before with good results.
     
  19. OP
    Mark1208

    Mark1208 Member

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    Could you please tell me how to remove centre vents so I can get to the top radio bolts.

    Thank you yet again
     
  20. OP
    Mark1208

    Mark1208 Member

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    Another question, yes I have to admit now I have to fit a windscreen glass aerial. Is this difficult and do you know how to remove passenger windscreen trunking so you can fit aerial to metal.

    Big thanks so far
     

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