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Wiring buttons away from the PCB

Discussion in 'General Electronics Discussion' started by labcoattech, Jul 23, 2015.

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  1. labcoattech

    labcoattech

    5
    1
    Jul 23, 2015
    Hi all,

    I've decided to upgrade the manufactures head unit in my car to a double din after market unit, as part of the upgrade I need to relocate some of the buttons but having looked at the PCB I am unable to figure out how to remove the buttons or rewire new buttons away from the PCB.

    I have taken some photos of the PCB but if you need any more then please let me know.

    Kind regards,

    2015-07-23 21.50.43.jpg 2015-07-23 21.51.25.jpg 2015-07-23 21.51.14.jpg
     
  2. Martaine2005

    Martaine2005

    3,514
    952
    May 12, 2015
    Hi Tech, we got rid of your coat in your introduction.
    They do look like tactile switches and the fascia buttons would have 'mushroom' stem.
    You can do two things. Use a DMM on all connections and find out which connection is which!
    Or MY simple way, just extend all 4 connections via wire to the new location.

    Martin
     
  3. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    hehe. Surface mount buttons :p

    Step 1.
    Use your eyeballs, and see if you can trace the traces from the buttons to a 'via' or another component on the board. A via, is a little metallic hole in the board used to allow traces to jump from the front to the back side. If you can identify where the traces for the buttons go to you can move to step 2.

    Step 2.
    Testing. Grab a multi-meter, and set it to measure resistance.
    Each button should have two traces leading from it, put each probe on each of the two wires and press the button. If you have picked the right traces, the meter should show 0Ω while the button it pressed, and something else while it is not. Make sure you identify the required pair of traces per button! (Remember the 'via's from the last step... those are the easiest to stick your multimeter probes onto)

    Step 3.
    Wiring a new button.
    Get some thin wire, tin the end with a little bit of solder, and proceed to join this wire to an ideal spot along the traces for each button. Simply put a new button on the end of the wires and you are good to go :D

    ** Disclaimer!
    Steps above assume 'Normally Open' button types. A Normally Closed button will behave differently and will require a 'destructive' alteration to the board to add replacement buttons. Be careful while soldering that you do not accidentally bridge any connections, and double-check the connections after you make the solder joint.
    The above steps will allow you to simply cut the wires you have added to resume factory operation, and if you do not damage the case, no one can even tell it's been modified!
    If the multimeter in step one behaves in reverse... ie. 0Ω, then you press the button and it changes, please let us know. (Digital meters will often show 0L... this is NOT the same as 0. 0L is 'overload' which means the resistance is too high to measure with the current settings.)
     
    Martaine2005 likes this.
  4. Martaine2005

    Martaine2005

    3,514
    952
    May 12, 2015
    I wish I could have wrote that without my fingers typing ahead of my brain!!
    There would have been so many words missed out .
    I have to hand it to you Gryd3, you are a good writer and explain things nicely.

    Martin
     
  5. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    haha. Thank you.
    Although, I do sometimes type faster than my brain.
     
    Martaine2005 likes this.
  6. labcoattech

    labcoattech

    5
    1
    Jul 23, 2015
    Awesome advice thanks, I'll let you know how I get on once I get home.
     
  7. labcoattech

    labcoattech

    5
    1
    Jul 23, 2015
    Hi,

    I have found the relevant points on the PCB using the multi-meter in continuity mode, I have placed coloured spots on the attached photo.

    The red and the green spots are for the button, with the multi-meter set to ohms 200 it shows 1 when the probes are on the points but as soon as I press the button it show's 00.2.

    The purple spots are for the LED inside the button which lights up when the red probe is against the bottom right and the black probe is against the top left.

    The next step is to find some push buttons and 2mm bullet connectors which would make connecting and disconnecting the buttons from the PCB easier. I'll post an update once I have things wired up.

    Thanks,
    Imran

    Left switch.jpg
     
    Last edited: Jul 25, 2015
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