So this is my first attempt at an Instructable. I do these kinds of simple mods fairly regularly but this may be the first time I've done one that others might actually be likely to encounter since there appears to be over 8,000 purchases of the same product from Amazon that I bought, and many reviews complained about needing an off switch. I knew my particular vehicle was new enough to automatically shut off the cigarette lighter receptacle when the ignition key was removed, so I wasn't concerned about that when I made the purchase. However in the mountain area I live in, radio signals can get very weak depending where you are and I found that when I had the device plugged in, but not in use, my FM radio signal would degrade drastically. So I decided to install a simple power switch. I have enjoyed and benefited from many Intructables over the years so I hope mine might help someone have an easier experience if they try this mod since I was not able to find anything online before my disassembly of the receiver.
Step 1: Getting to the Guts
The whole reason I decided to share this little project was caused by 2 little screws. I have disassembled many laptops, monitors, external drives, etc. in the past so maybe I should have been more aware of hidden screws, but I didn't figure this one out until I ended up breaking the casing. I spent a good good half hour or more trying to open it before I discovered that the screen was actually just a thick sticker hiding the screws underneath. Perhaps I haven't had enough experience with smaller devices yet, but this was very frustrating to me before I cracked the bezel and the "sticker" revealed itself. So just peel off the screen first with a guitar pick or something similar, remove the screws, and then pry gently but firmly around the edges.
Once you get the top off be careful not to pull out the wires for the microphone.
Step 2: Remove the PCB
Carefully remove the circuit board to access the back of the device. I didn't think to take pictures before I did this, but basically I just found a spot near the bottom that was large enough to house a small switch and drilled 2 small holes side by side and then cleaned out and squared the hole with a razor knife and small file. Once I was able to get the switch to fit into the squared hole, I drilled the smaller holes for the screws to hold it in place.
Step 3: Rerouting the Hot Wire
Again this was an afterthought, so no pictures before...
I warmed up the solder on the red wire connection labeled 5V and removed it.
I happened to have a defunct DisplayPort to VGA adapter hanging around, so I cannibalized that for the fine copper wires within. After removing, sizing and prepping a red wire from the adapter, I soldered one end to the 5V connection terminal.
Step 4: Connect the Switch
Now just take the original 5V wire and give it room outside the wire casing to reach and solder it to one furthest side terminal of the switch, and solder the new 5V wire to the next closest terminal. (should be the middle terminal)
Step 5: Arrange Wires and Reassemble
Remember that these are all very thin wires so be careful throughout, but then be sure that none of the wires get pinched when reassembling. I took mine out to the car before reassembling just to be sure everything was working correctly and it was. So I was happy, and now I can listen to the radio without having to yank the unit out of the CL socket. I'm pretty sure these companies will start adding an off switch before long after all of the feedback, but until then I hope this helps someone out there. Cheers!