I have a AM/FM radio board I found and am trying get playing through a small speaker. The other components were missing so I don't know how this connects to the rest of the system which had a CD player, tape deck and the like.

The board has a single set of input wires pictured below.IO Wiring

The on board chip is a Toshiba TA8167N which I have found runs on 3 volts and have managed to power. Now I am trying to figure out what is required to connect to the speaker.

As there is only a single out for L and R which connect to the 'R-Out' and 'L-Out' pins on the chip I'm not sure how to complete the circuit. From reading around it looks like I need an 'R-Ret' and 'L-Ret' respectively to complete it but there is no wiring for this available.

I think SL connects to the Stereo LED but I can't follow the MO or MU to the chip as the connections sit under the tuning wheel.


PCB picture added.

enter image description here

  • \$\begingroup\$ A radio has an RF aerial input. L, R, Mo (Mono), and Mu (multiplex) are all outputs. Ther's no evidence here that you need any more components, but if you do, a closeup of a PCB isn't sufficient to answer the question. You need to provide a schematic. \$\endgroup\$ – user207421 Jun 20 '15 at 2:18
  • \$\begingroup\$ I've looked for a schematic. Board Number is 13011-514-810 but with no success which is why I posted the link to the micro controller as it was all I had. Maybe my question was phrased poorly. As I have a single wire out for say the left speaker I'm not sure how this works going to a speaker where I require both positive and negative wires. \$\endgroup\$ – EnE_ Jun 20 '15 at 2:27

The Toshiba TA8167N has single-ended outputs -- the return for both L and R outputs is the GND pin of the chip (pin 9). Is pin 9 connected to the "-" pin of the connector you showed?

Tuner chips like these are rarely connected directly to a speaker. More typically, the tuner chip output pin is connected through a 4.7 uF capacitor (as shown on p. 8 of the TA8167N datasheet) to a "volume knob" connected to an audio amplifier such as the Texas Instruments LM386N-4, as shown on p. 6 of the LM386N-4 datasheet.

The LM386N-4 and many other audio amplifiers are also single-ended -- the return is the GND pin of the chip. You'll need 2 such audio amplifiers (or a "dual amplifier"), one to amplify the L signal and the other to amplify the R signal.

(Could you show a photo of the entire PCB? Perhaps your PCB already includes a volume knob and perhaps even an amplifier).

  • \$\begingroup\$ Thanks for the info, I have added the full PCB. The volume knob was definitely elsewhere. \$\endgroup\$ – EnE_ Jun 20 '15 at 4:27
  • \$\begingroup\$ Also, pin 9 is connected to the '-' pin of the connector \$\endgroup\$ – EnE_ Jun 20 '15 at 7:21

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