Adding a AUX Jack to this 80's Delco AM/FM STEREO

Discussion in 'General Electronics Chat' started by Fisher77, Sep 19, 2016.

  1. Fisher77

    Thread Starter New Member

    Sep 19, 2016
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    Been searching around on the net to find directions to install a aux jack on this Delco 16009960 stereo. Have not found anything to help me out. Thought I would ask here to see if someone can enlighten me on how to accomplish this task. Thanks for any help.

    Here are some pics of the inside of the stereo:
    unnamed (17).jpg

    unnamed (18).jpg
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    Do you have an audio amplifier handy? Something like PC speakers will work fine.
    Get yourself a 10μF, 25V electrolytic capacitor.
    Anything from 1-100μF, 16-63V will do for now.
    Use one lead of the capacitor as a probe. The other lead goes to the input of either channel of your PC speaker. Connect the ground of the speaker jack to the ground of your radio.
    Probe around your radio until you hear some decent muzak.

    One good place to start is at the center terminal of the volume control.
    Take a better photo (well focused) of the component side of that circuit board on the left hand side of the radio. That is where the audio amp is located.
     
    Last edited: Sep 19, 2016
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  3. Fisher77

    Thread Starter New Member

    Sep 19, 2016
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    I do have a PC speaker I can use. Here are some better pics of the boards. Let me know if they are what you need to see. Thanks MrChips.

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    unnamed (3).jpg

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  4. MrChips

    Moderator

    Oct 2, 2009
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    What do you mean by AUX jack?
    Do you want to input your own music into the radio
    or do you want to take the radio output to an external amplifier?
     
  5. #12

    Expert

    Nov 30, 2010
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    An AUX jack is a, "line level" input.
     
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  6. Fisher77

    Thread Starter New Member

    Sep 19, 2016
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    Input my own music.
     
  7. MrChips

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    Oct 2, 2009
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    Sorry. Initially I was thinking the other way (play the radio out).

    This is not going to be easy. How difficult is it to remove that side board to look at the solder side?
    Someone else has already tried this here.

    The volume control pots are soldered into the PCB.
    You will have to cut the PCB traces and feed your signal into one end of the pot. This will permanently disconnect the internal radio.

    You can also look to see how the radio signal gets to the pots. Is there a connector or wires?
     
  8. Fisher77

    Thread Starter New Member

    Sep 19, 2016
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    Dont see any plugs. There are wires that look like they connect to the pots. Green wire seems to be connected to the first pot, no wire to the second, orange wire to third pot and nothing to last pot. Then there are red wires on the end of the pot stack, There is also a red wire just to the rear of the fourth pot. It does not look to be connected to the pot, but hart to tell without being able to see the back of the board. Getting that side board out would be quite a chore. May have to disassemble part of the chassis to get it out.

    Ok, I traced the red wire to the rear of the 4th pot. It runs over to the small board for the main connector at the rear of the stereo. That connector is the power, ground, and speakers. Orange and green wires both go to the solder side of the bottom board. The board is labeled out+ next to green and orange wires.
     
    Last edited: Sep 20, 2016
  9. crutschow

    Expert

    Mar 14, 2008
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    This article may help.
     
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  10. Fisher77

    Thread Starter New Member

    Sep 19, 2016
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    Thanks for the article crutschow. It has some good info.

    Ok MrChips, I managed to get some pics of the back of the side board that the pots are soldered to. First pic is the whole board, second is a closer view of the end with the pots.

    unnamed (5).jpg

    unnamed (4).jpg
     
  11. MrChips

    Moderator

    Oct 2, 2009
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    We are going to assume that the ORANGE wire leading into the board is the LEFT channel input.
    The GREEN wire is possibly the RIGHT channel.

    Unsolder the ORANGE wire where it enters the board.
    Feed a test signal from a music source (e.g. mp3 player) into the solder connection.
    Connect common GND between the player and the radio.
    Note that the volume control will affect the sound output.

    If you finally decide to go ahead with your retrofit, you will need to purchase a switched audio jack like the one shown in the link in post #9.
     
  12. Fisher77

    Thread Starter New Member

    Sep 19, 2016
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    Will remove one of the wires and test it. I picked up one of the jacks this morning at radioshack. I was surprised to find it actually still had the same part number. I took some pictures of the back of the board with the wires out of the way. And some better ones of the component side. I also tested the 4 post. Pots 1, and 2 in the stack are for the tone, and balance. Pots 3, and 4 are for the volume.

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    unnamed (9).jpg
     
  13. Fisher77

    Thread Starter New Member

    Sep 19, 2016
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    First off, thank you for the help. This seems to be a great forum with loads of good info.

    Ok, here is the rub on this. I have managed to get this to work. Had some more help from a fella by the name of budm. You have to gain access to the amp board to do this. Requires a little disassembly, but its not to bad.

    Here are the connections as follow:
    1) Remove the Orange wire from the 'L' pad and then solder the wire to pin 4 of the jack.
    2) Remove the GREEN wire from the 'R' pad and then solder the wire to pin 3 of the jack.
    3) Solder 10uf/25V cap with + leg to pin 5 of the lack, the - leg to the 'L' pad.
    4) Solder 10uf/25V cap with + leg to pin 2 of the lack, the - leg to the 'r' pad.
    5) Solder the GND wire to pin 1 of the jack and the end to the GND pad on the board marked with solid red circle as shown in the pictures.

    Here are the connections on the board. Pic courtesy of budm.
    INPUT JACK.jpg

    Parts list:
    2740246 - 1/8" switching panel mount phone jack (Radio Shack)
    shapeimage_2.png
    2 x 10uF, 25V electrolytic capacitors.
    wire to make the connections with. I used 22 gauge, but you can use whatever you have on hand.
     
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