The Bose Lifestyle 20 is a ubiquitous piece of hardware. This system, manufactured near the very end of the 20th century, is a testament to cool design and excellent sound (as far as this non-audiophile can judge). About 20 years after their manufacture dates, these units have two common issues: dim to dead display and faulty CD changer. Swapping 5 capacitors fixes the display issue but fixing the CD changer has befuddled me. So, inspired by some clever eBay sellers who had already capitalized on the idea, I installed a Bluetooth receiver in place of the CD changer. I didn't purchase and reverse engineer their designs, but it may have been a better use of time had I done so...
Some notes on how this modification will affect the system:
- The Bluetooth adapter will always be on. This draws very little current, espcially when idle.
- BT audio will only play when the unit is powered on into CD input. So, after changing sources away from CD and navigating back to CD, audio will not play until the device is powered on and off.
- Similarily, using media controls like Play, Pause, Rewind, Next disc, etc will stop audio output until restart.
Fortunately, it only takes a second or two for the device to restart.
I've determined that the green wire signals the CD player's pause/rewind/next disc operations. If someone else has more hardware aptitude, I'm sure there's a way to overcome these issues. With the proper hardware, we could actually make the media controls work with Bluetooth!
Why not just buy a bluetooth adapter and plug it into one of the units input ports?
- I'd recommend that over this! A good BT receiver
- This solution is primarily for people who do not have any free input ports.
- Alternatively, you can follow this guide to install BT in your unit and solder the audio output to one pair of the input ports as opposed to the CD port. This way you'll have a self-contained BT unit that doesn't require a restart everytime you want to listen to BT.
- Side note: a faulty CD player may incessantly make grinding noises. Removing the CD player will obviously fix this issue.
- Bluetooth (BT) Adapter with Aux port preferrably.
- Linear voltage regulator (L7805CV) to step down the board's output voltage of about ~15v down to 5v
- A micro usb cable to solder to the board's power and plug into the BT adapter
- Ground loop isolater for buzz-free audio with 1 whole aux cable
- From my tinkering, here's my understanding of the issue: powering the BT adapter from the Lifestyle's CD port causes a buzzing noise when listening with headphones due to a so-called ground loop. Installing a ground-loop isolator fixes the problem, but adds about $8 of cost to our project. There's almost certainly a way to configure the circuit without introducing a ground loop, but I'm not much of a circuits guy. Your feedback is welcome.
- Without ground loop isolator, the buzzing noise may only be present when using headphones (since the headphones are powered by the Lifestyle 20). I haven't tested this.
- Half of an aux cable to connect the BT adapter + isolater back to the Lifestyle's CD port.
- Heatshrink or other casing material (electrical tape) to protect soldered wires
- (Optional?) Protoboard as a base for all of your connections
- Wire Stripper
- Soldering Iron
- Phillips and Flat head screwdriver to disassemble Lifestyle unit
Disassemble the unit. Covered in the first half of this video
Remove the CD player and cut the wires leading into it as close as possible to the CD player. So, you should have a long strand of wires with a connector at the end.
- Cut off one end of the aux cable and strip its wires. There should be a red for right audio channel, white for left audio channel, and a shared ground wire.
- Cut off the full-size USB end of the micro USB cable. There will be a few wires, only strip the red (positive), black (negative) wires. ** Note: sometimes cheap micro USB cables will have this configuration backwards: red (negative), black (positive). This can be tested by plugging the full USB end into a USB power brick and testing the voltage with a multimeter or through trial and error, reversing the polarity probably won't break anything.
- Strip the red, and yellow wire from the CD harness
- Combine the red, yellow, aux cable ground, and micro-USB groudn wires together and solder to the middle pin of the linear voltage regulator. ** It may be easier to solder the wires together with a jumper wire that leads to the voltage regulator.
- Solder the purple CD harness wire to the input pin of the voltage regulator (the L7805CV's input pin is marked ST)
- Solder the positive wire of the micro-USB connector to the output pin of the voltage regulator
- Plug in the micro-USB cable into the BT adapter
- Solder the orange CD harness wire to the red aux cable wire (LEFT audio channel)
- Solder the brown CD harness wire to the white aux cable wire (RIGHT audio channel)
- Plug in the whole side of the aux cord into the ground loop isolator.
- Plug in the one end of the full aux cord into the ground loop isolator and the other into the BT adapter
To play BT audio, connect your auxillary device to the BT adapter. Turn on the Lifestyle 20 and navigate to CD. If no audio plays, turn the unit on and off. Audio should now play.