Introduction: Boombox Transforms Into Car Stereo
This instructable will guide you through installing a truly custom radio in your vehicle. It uses the factory speakers and can look pretty nice if you try. I had my car stolen in 2007 and they took out the CD player that the previous owner had installed. This caused some damage that can be seen in a few pictures but basically it just left me with a hole in the dash. I put in another amp circuit from a 5.1 system and used it for 5 years because it worked but I was never really happy with it. I recently started entering these instructable contests and figured I should take the opportunity to redo my radio, especially after my mother-in-law gave me this malfunctioning stereo. The CD player (which is all she used) did not work and I tried to fix it but couldn't...
So, now I have all the parts I need to install a customized, new-to-me stereo in my car.
Step 1: Take Apart the Stereo
Every stereo is different but you need to find one that operates its circuitry on 12ish volts. This is 8 batteries (AAA, AA, but probably C or D) in series... 1.5 volts x 8 = 12 volts. You can also test the voltage on the unit but you need to be careful as you can find line voltage... You should not plug in the stereo while it is halfway apart and touch the contacts powering the board with the voltmeter because that can be very dangerous even though it would allow you to determine the operating voltage...
I got lucky on the layout of this unit. Different arrangements might not have been as easy to install. You can see how much smaller it will be with the tape section removed.
Make sure to note where the power to the circuitry is coming from. Usually it is easy to spot as a red and black cable but not always...it must originate at the power source so just start at the transformer and follow along until you get to the main circuit board. The cable you followed was probably the power cable.
Step 2: Determine What to Keep
Sometimes circuit boards will be all over the place... sometimes all-in-one. All I had to do to remove the tape player section was unscrew some screws and then I used metal cutters (strong scissors) to cut off the plastic part.
Step 3: Testing Power
It is a good idea to test the power at least once and after major changes. For my 12 volt source I used a backup battery/air compressor that I use to jump off the car sometimes.
Step 4: Coverting Tape Input to 1/8" Input
I chose to hack the tape input because the CD was more difficult (for me at least) and I wanted to keep the radio function. The cables seen above are what were attached to the the tape player. When looking at the tape head I saw the ground easily (attached to the head's casing) and followed it to the center pin of its plug, indicated on the picture of the circuit board. This ground traces around the board and ends on the pin connected to the brown wire. I am bypassing this board because the devices that will be plugged in will have their own amplification.
The 1/8" cable was threaded through a slightly enlarged microphone opening (drill) and knotted to hold securely. I clipped and cleaned a connection on each wire in the strand and connected the brown to ground. After plugging an MP3 player into the cable and a speaker into the left port, I touched the signal wire (either one) to each wire and the green one was a hit so I tied them together. Then I switched the speaker to the right port and tried the red wire on the remaining wires and the red one hit so they were tied together. I just twisted the wires together and used electrical tape.
Step 5: Add Better Attachments
This step is not really necessary but I wanted to wire my speaker connections to the board so I didn't have to get new connectors or cut the original speaker wires...
I simply verified the connections and soldered on my wires. I applied hot glue to secure the wires.
Step 6: Car Prep Work
This is about what the dash looked like after the car was stolen... I found the switched power line and ground and tested them with the voltmeter. Then I checked the fit and it was perfect. (If it had been less than perfect I was planning to use some of that soft packing foam to help seat the radio against the dash.)
Step 7: Install New Stereo and Enjoy
Turn the key and enjoy.
Here is a video showing operation of the input and the radio.