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DIY'ing on Oem HU (strictly for/with proffessionals in electronics)

Discussion in 'Do It Yourself' started by jayadev, Aug 11, 2011.

  1. jayadev

    jayadev Esperto

    Messages:
    1,057
    Kannur, India
    Kannur
    Grande Punto 1.3 90 HP
    Many of of us are totally frustrated by Quality of OEM HU.
    Nothing much can be done in general other than upgrading to new head unit but depriving The fun of blue n me and steering mount controls.
    so let us see if we can do anything going through technical (electronically)

    let's not get bored with all technical terms and jargons and keep the post brief and comprehensive-through pics.

    front.jpg

    board.jpg

    board rez.jpg
  2. Viny

    Viny Esperto

    Messages:
    1,742
    :)
    Great stuff
    Can you tell me what made you to do this operation :p
    And what was the final outcome :)
    Last edited: Aug 11, 2011
  3. Italia-Linea

    Italia-Linea Staff Member Janitor

    Messages:
    2,123
    Pune
    nice one Jaydev. nice way to get preout from the HU. however the pics seems to be incomplete. i believe you are in process of loading more pics?
    also explain us your DIY of connecting the RCA preouts by bypassing the power amp.

    step by step method will be useful for all of us who are layman
  4. jayadev

    jayadev Esperto

    Messages:
    1,057
    Kannur, India
    Kannur
    Grande Punto 1.3 90 HP
    Thanx
    2 Things ,
    1.I know electronics
    2.I am a hardcore audio enthusiast.

    hmm that's in climax..!!

    sure coming up

    blpnt ic.jpg

    board.jpg
    Last edited: Aug 11, 2011
  5. gurjinder

    gurjinder Staff Member Janitor

    Messages:
    3,989
    Punjab
    Great stuff Jayadev. I'm not sure what the climax is , but to see you surgically analyse the OE HU is great indeed.

    Cheers.
  6. jayadev

    jayadev Esperto

    Messages:
    1,057
    Kannur, India
    Kannur
    Grande Punto 1.3 90 HP
    This blaupunkt DSP processor is same processor used in "Blaupunkt Queens MP56" HU and Blaupunkt MP66 HU. hope you get me what i mean...!!

    What they left out is Variable subwoofer output, plus 4-ch preamp outputs to add and control additional amplification . Maybe a cost cutting thought being an oem product they pressumed it to be driven by 4 speakers only .
    and Fiat do not allow anything else.
    Last edited: Aug 11, 2011
  7. jayadev

    jayadev Esperto

    Messages:
    1,057
    Kannur, India
    Kannur
    Grande Punto 1.3 90 HP
    I expect it to raise interest in great ICE lovers and sort of Myth buster.
  8. jayadev

    jayadev Esperto

    Messages:
    1,057
    Kannur, India
    Kannur
    Grande Punto 1.3 90 HP
    A quick jump to the motive.
    let pics speak.

    conxn.jpg

    ic pin.jpg
  9. jayadev

    jayadev Esperto

    Messages:
    1,057
    Kannur, India
    Kannur
    Grande Punto 1.3 90 HP
    Have a look at the power amplifier ic inside HU (TDA7385) last pic. that is barely 25 dirty watts into 4 channels.
    and i do not need dirty things in my car.

    So i desoldered and lifted the input feed leg 12 and 15 of the ic (pointers in pic) so that this dirty power amp is isolated from onboard DSP (above mentioned processor).
    Those who like to have pin configuration of tda7385 ic please check the datasheet in ST website.
    Now come to the first pic. (sorry for crazy picture sequence pic loader of TFI is from stone-age )
    two wires being soldered( by me) underside of same ic where legs has been raised.
    So i get the feed from DSP but does not goes to OEM hu power amplifier.Instead i get it out as 2 channel Pre out

    so what are the gains?

    coming up!!
    Last edited: Aug 11, 2011
  10. Italia-Linea

    Italia-Linea Staff Member Janitor

    Messages:
    2,123
    Pune
    hi javadev, hats off to you. indeed you are an electronic geek :)

    well coming back to your pics in first one where you mentioned pin 14 and 12 of power amp and common ground i can see 2 black wires soldered to 14 and 2 red wires soldered to 12 and one soldered to the common ground.
    where did 2 set of wires come from?

    are these pins 12 and 14 left and right channel? or front and rear?

    what about pins 11 and 15? what do u mean they are for other 2 channels?

    now in second pic i can see you uplifted 2 legs right? which pins are these legs connected to 12 and 14?

    you also mentioned in one pic that this is the area for pre out and sub out. what is that area exactly? do u mean we can tap pre outs directly from there?

    how do you get a dedicated sub out? does it have LPF from the DSP directly?

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