When I got it home, I cleaned it up- It appeared that the truck had been sandblasted with it in place, and the case was FILLED with sand. There were a few loose connections here and there, but after a bit of tinkering, I got it going. It made an annoying buzzing sound, though, and didn't seem to receive any stations. I could attribute the lack of reception to not having an antenna attached... But the buzzing was another problem. I figured i'd do some troubleshooting to find out what it could be.
I've messed with old electronics before, and know that often the 'weak link' is the old capacitors in the radios. A little web research confirmed that this could very easily be the problem, so I decided to try replacing the electrolytic capacitors, which can dry out over time and cause problems. The factory radio has 2- a 50µF and a 500µF. This image shows their location on the board-
Replacing them is a simple matter of removing the old ones, and soldering in new ones in the same location. Good luck finding the EXACT capacitors- But, you can get close enough at Radio Shack-
They stock 47µF and 470µF capacitors, which are close enough. They are about $1.50 each. Don't worry that they are significantly smaller than the original ones in the radio, like many other things, capacitors have shrunk quite a bit in the past half century or so.
This is the location on the back of the board, where you'll be working from-
The 50µF is close to the top of the board, so it's not tough to tell which leads to remove, but the 500µF is tucked away down inside, and could be a little tougher to find, so just look at the picture. Remember that capacitors are polarized, you have to get the "-" an the "+" into the right holes... With both of these, the negative was on top.
Once I replaced the capacitors, I powered the radio up- and the buzz was GONE.
Next, I decided to try a little 'hack' that I had seen some instructions for online- Adding a jack for an MP3 player input. The instructions were a tad vague, but I worked through them and figured it out. I was able to get all the parts I needed at radio Shack, for about $5.
It involved soldering a few wires into the radio, between the audio inputs and the volume adjustment knob. Then, you run some wires out of the radio chassis, to a 1/8" stereo jack. You can then connect pretty much any device that has a headphone output to it that you want.
This is the board inside the radio where the connections are made-
The stereo jack that I bought is also available at Radio Shack. If you use a different one, the pinout might be a little different, and you'll have to figure out what goes where. You'll also need a resistor, I used a 100Ω. Here's how the plug is wired-
The black wire will go to the ground. The resistor connects the two stereo audio outputs into one, through the resistor. I just connected my output wire (green in my case) to the resistor wire to keep things simple.
I hooked it all up= And it worked!
It actually sounds pretty good through the old radio. Of course, it's not going to sound GREAT- For one thing, it's mono... The factory system isn't what you'd call great sounding anyway. But, it's nice to have the ability to plug an MP3 player in, unless you really like listening to VERY limited AM stations
Using My IPhone with it, I can also route calls through the speaker, as well as GPS directions, etc. Also, I can listen to streaming radio as well. I think it's a pretty worthwhile upgrade, considering it only cost a few bucks and an hour or two of time!
-Andrew
