AUX Input Help

Discussion in 'Automotive Electronics' started by rl0089, Feb 22, 2016.

  1. rl0089

    Thread Starter New Member

    Feb 22, 2016
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    Hello Everyone,

    I was hoping I could find some help with an audio issue I'm experiencing with my car and the AUX input I (attempted to) set up.

    The car in question is a 2006 Volvo XC90, and as I understand it (I'm an electronics novice) the FM signal is converted to a digital signal by the FM tuner so traditional antenna adapters are useless with this setup. There are instructions that were created by a Volvo enthusiast to add an aux input by soldering the two channels on to the positive ends of two capacitors. I attempted to add the aux line and initially had no problems. The following day I went to use the aux line with my XM radio, which needs a power source to run, and I got a high pitched squeal, which I was expecting with something drawing power at the same time as using the audio. Later that day I installed a ground loop isolator to eliminate the noise and my left channel (driver's side) was completely gone! The high pitch noise is gone but I only receive sound out of the right side of the car. Like I said, I have a limited knowledge of circuits, I have a basic understanding of the components and I'm not afraid to do some soldering, but I'm stumped here. Could it be I damaged the capacitor when soldering the left channel? Or is it something more complicated. Below is the link for the write-up for adding the aux and a few pictures of the FM tuner. I would appreciate any help with this I can get. Thanks!

    http://forums.swedespeed.com/showthread.php?212123-AUX-installation-on-XC90-2006

    [​IMG]

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  2. rl0089

    Thread Starter New Member

    Feb 22, 2016
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    Anyone?
     
  3. rl0089

    Thread Starter New Member

    Feb 22, 2016
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    Since I really have no guidance on this, I haven't received a response on the Volvo forums either, I am guessing at this point that the capacitor is shot. I'm not going to touch the board until I have some info on what could be causing my issue, but if I were to replace a capacitor, how would I identify the type and source? The capacitor I believe is the issue is C401, or the one the poster marked with a red + sign. Again, I appreciate any help. I am lost on this!
     
  4. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    If you are looking at C401, there are three numbers printed on top. The first is a manufacturers custom designation, the second is the value of the capacitance in microfarad, uF, and the third is the voltage rating.

    So, the part is listed as follows:

    CCJ
    .22
    50V

    It is a 0.22 microfarad capacitor with a 50V rating.
     
  5. rl0089

    Thread Starter New Member

    Feb 22, 2016
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    Thank you. Would any 0.22uf 50v capacitor do? Would it have to be the same style capacitor if I did replace it? I see many more options as a ceramic disc.
     
  6. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,795
    949
    You need the exact replacement. Others would work, but probably will not FIT in the spot you mount it. If you know there is enough room above the board then you can safely substitute another size cap for the surface mount type you have.
    Have you examined you solder work with a magnifier? A short, invisible to the naked eye, might be the source of your trouble.
     
  7. rl0089

    Thread Starter New Member

    Feb 22, 2016
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  8. rl0089

    Thread Starter New Member

    Feb 22, 2016
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    One other question. Is the black plastic at the base of the capacitor just that, a base? Is it integrated into the capacitor in any way? Or is it just the base with the capacitor soldered to the board underneath it?
     
  9. absf

    Senior Member

    Dec 29, 2010
    1,493
    372
    Yes, it is integral part of the cap. So when you unsolder it, do be careful not to lift one side up while the other side is still stick on the PCB. You might lift the copper trace if not experienced.

    smd cap3.jpg

    Allen
     
  10. GopherT

    AAC Fanatic!

    Nov 23, 2012
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  11. rl0089

    Thread Starter New Member

    Feb 22, 2016
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    Believe me, I wish it was easier to install of double din and forget about the stock radio. I'm fairly new to Volvos but from what I understand about the sound system in this car is that it works over fiber optics. If I wanted to use an aftermarket radio I would probably also need to install an entire independent speaker system. So I'm trying this AUX mod for the time being. All I really want to have is the ability to play off my phone or from an XM radio receiver.
     
  12. rl0089

    Thread Starter New Member

    Feb 22, 2016
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    Thank you for that pic and explanation. Do the capacitors with the base have a special name or term? Would I be able to reuse the one currently on the board or would it need to come from a new capacitor? I haven't seen the base with the capacitors I've been looking at purchasing.
     
  13. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
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    What you are looking for is a surface mount electrolytic capacitor.
     
  14. rl0089

    Thread Starter New Member

    Feb 22, 2016
    9
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    Thank you!
     
  15. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,542
    1,251
    It is just a base, but it is an insulating base. The outside skin of the capacitor is a small, thin metal can. If that were to sit directly on the pc board, eventually the edge would grind through the solder mask covering a nearby trace and make unintended contact.

    ak
     
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