I was given this rather cool looking boombox. Unfortunately a lot of components on the circuit board were black and blown and it would have been a lot of work to try and fix. I guessed that the speakers would probably work, so I decided to wire them up to a new amp instead.
- Broken boombox.
- 12V car amp.
- 12V battery.
- Some odd lengths of wire.
- Car blade fuse holder.
- Car blade fuse.
- Self taping screws.
- Basic electrical tools; snips, strippers, screwdrivers etc.
- Stanley knife.
- Soldering iron and accessories if you want to be fancy.
Step 1: Take the Boombox Apart
As this is a nice old boombox it was designed to come apart easy. 8 long machine screws accessible from the back allowed me take the back off.
There were a few wires that joined the back to the main part of the boombox. After checking that these weren't for the speakers I just snipped them so I could completely remove the back.
It was pretty easy to spot the 8 wires attached to the speakers. My boombox had 4 speakers in total, 2 tweeters and 2 mid-range, 2 wires for each.
The boombox has an amazing double aerial and the car amp I'm going to use has a built in FM receiver with a small aerial. So my plan is wire the new car amp to the boombox aerial, so I left the 2 wires attached to the boombox aerial, that were very easy to spot. Your boombox might just have 1 wire for the aerial.
My original plan was to remove everything else from the boombox. But a lot of the switches and knobs were directly attached to the circuit board. So instead I just cut all other wires to make things a little easier. I also removed the transformer and a few other bits I could, just to make the thing lighter.
Step 2: Extend Wires, If Necessary
A couple of my speaker wires were pretty short, so I soldered some longer lengths onto them. You could use any technique to join wires if you don't have access to a soldering iron. Chocolate blocks, or just twisting and taping can work well.
Make sure you cover any bare wire with electrical tape.
Step 3: Start Feeding the Wires Out the Back of the Boombox
I cut a small hole in the back of the boombox for all my wires. I used a Stanley knife with a nice new sharp blade. I cut through the air vent in the back of the boombox, that made it a lot easier.
As I fed my wires through the hole I taped and labeled them, so I knew what was what... Aerial, left tweeter, right tweeter, left main, right main.
Once I'd fed all my wires through I screwed the back back on the boombox.
Step 4: Screw Your Amp Onto the Back of Your Boombox
4 self taping small screws worked well for this, it was a little hard to get them going as the boombox is pretty tough plastic. I used a braddle to make a small hole and with a little effort the screws bit in the end.
Step 5: Wire Up Your Speakers
My boombox has four speakers and with a stroke of luck my car amp has four speaker connections, which made this step very easy.
Step 6: Wire Up Your Aerial
My original plan was to solder the wires from the boombox aerials onto the car amp aerial. But the solder didn't want to take to the aerial.
Instead I removed a small machine screw on the car amp aerial, which allowed me to remove the aerial. Then I wound the boombox aerial wires around the machine screw and tightened it up, seemed to work well.
Step 7: Make a Power Lead for Your Battery
I'm going to use a fairly small (20Ah) 12V sealed deep discharge battery for this boombox.
You could use any 12V battery, but I prefer sealed as there's no chance of spilling acid anywhere. And deep discharge is also good because if you completely drain the battery you're not going to damage it.
You find these kind of batteries in electric bikes, golf carts, disability scooters, that kind of thing.
My battery has fairly small connectors and the car amp has a standard female jack for power.
So I made a couple of fairly long lengths of wire to join the battery to the amp. I picked up a male power jack where you can just screw the wires into the back. These things are great! I hate soldering power jacks.
I also soldered a car blade fuse holder on the positive lead. Not a bad idea to have a fuse just in case.
Step 8: Wire Up Your Battery And... BOOM!
This thing is loud! Which is a good thing.
Radio worked great, speakers sound great.
Now I've just got to work out how to attach it to my bicycle!