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FM Radio Project

Discussion in 'General Electronics Discussion' started by Flapjack, Apr 7, 2014.

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  1. Flapjack

    Flapjack

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    Apr 7, 2014
    I purchased a "ChatterPals" 2002 FM radio from a thrift store a few days back and have decided to take on the task of fixing a miniplug audio input into the device; the problem being that I have little experience figuring out what does what on a circuitboard. The most experience I have had with soldering and fixing electronics was replacing rca cables and internally grounding my technics turntables as well as replacing the tonearm. That was a more basic fix though.

    It would be much easier if I was just fixing the cables to the speaker connects, but it is slightly more complicated. The front of the device has a toy frog who's mouth opens and closes in response to louder audio frequencies (speech/beats/etc) so that it can talk. the back of the jaw-piece is connected to a small motor that rotates up and down and is connected to the main board.

    I would love to just replace the antenna with a miniplug male cord, but I know this is not at all the case with audio electronics. My question being, how do I find out where the audio input pins begin and the FM radio transmission ends? I figured I would have to solder the ground cable from the miniplug to what I believe to be the grounding cables in the power supply.

    photos:

    front of the frog

    [​IMG][/URL][/IMG]

    back of the frog and small rotating motor

    [​IMG][/URL][/IMG]

    there is an FM adjustment on one side that apparently adjusts how much the frog opens and closes his mouth. All the way to one side, it stays completely closed; all the way to the other it stays completely open. Somewhere in the middle depending on the audio will make the mouth open and close in respect to the song or voice on from the radio(audio)

    [​IMG][/URL][/IMG]

    the battery pack on the back takes 3 AAA batteries, and the power seems to run through a black wire to the optional A/C adapter input on the side, then through a black wire to the main switch that turns it to on, just radio, or radio with the mouth motion (on the other side of the board). A grey wire returns the power to the FM adjustment, and another grey wire returns that signal to the power again. I believe this to be the ground and would solder the miniplug's ground somewhere along this circuit.

    [​IMG][/URL][/IMG]

    closeup on the board, and it is a mess. I don't know what order the manufacturer soldered it in, but it is difficult to see what goes where. The blue wheel controls volume, the white wires leading off the right side of the board connect to the speaker, red and grey wires are on the main power switch, yellow and black wires lead to the motor, and the other white wire leads to the antenna. The brown one just leads to another part of the board. The blue and green ones seem to be soldered to the FM adjustment dial.

    [​IMG][/URL][/IMG]

    this is the flipside of the board. The main chip covered up by the black piece lists it as " D2822A over JK3 II"

    [​IMG][/URL][/IMG]

    This is a wide shot of the toy taken apart

    [​IMG][/URL][/IMG]

    any help is greatly appreciated
     
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