In August, I bought a Skoda MS402 car radio from a car boot fair, for the very reasonable price of £1. Since then it has been connected to a power supply by the side of my bed, getting used very rarely. Recently I purchased a new laptop, and as is common on laptops, the speakers are terrible, and so I needed to do something about it.
I wanted a method that could still allow the tape player to be used, and as such when playing from the input the tape motor is still spinning but is nearly silent.
After opening the radio, my first step was to search Google for any chip datasheets that could tell me where to easily input some audio. I found the Pre-Amp for the cassette deck (TEA0676T), and decided this would be a good place to connect some wires for an input socket.
If I solder wires to the output stage of the pre-amp, the signal will go to the main audio processor.
The pins don't have left or right designators on the datasheet, just 1 and 2.
This is the main audio processor, I could have soldered to this, however the pin spacing is minuscule, so I thought it would be best not to...
I then soldered the 2 audio input wires to the chip and soldered the other ends to a 3.5mm audio socket.
The ground cable from the audio socket is connected to the radio chassis.
Using generous amounts of hot glue, I stuck the audio socket into a hole I made in the radio chassis.
The socket from the outside of the case.
The display when playing from the audio input.
The back of the case with the case closed.