For this log let's start at the most logical place: the end.
The final version of my android car media player. The original tablet that I was going to use for this project had some major issues as everything started to come together. First of all the tablet was too large to fit behind the trim of my Subaru Baja without cutting into the stock dash trim. More importantly when I was performing my final "dry fit" with the 7" tablet connected to my cd player, the cable connecting the touch screen to the main tablet board snapped in half. This is not a major deal since a new touch screen overlay w/ connecting cable will cost me ~$5 on ebay.
I decided that I would rather use a smaller tablet than modify my vehicle (everything I have done so far can be reversed). I found a cheap Coby Kyros tablet on Amazon and ordered it. Tablet was received, disassembled, separated from its battery, and made to draw power from a modified usb cable connected to the 12v to 5v converter.
After all of that was working I cut a face plate from the hard board to fit my new media player and filled in the gaps with plaster. This is the only part of the project that I was not happy with, I did not take the time to fully sand down the edges which are very visible after the face plate was painted.
This was the final fit test before painting and putting everything back together. Overall I am very happy with the project and I still have the original broken tablet to use in another project.
A final look at what could have been with the 7" tablet.
Screws drilled out and stock cd player has been removed (undamaged :D ). Tonight the aftermarket cd player will be installed and the tablet will be test fitted in it's new home. After deciding on installing the tablet behind the face plate that will be cut from the hard board rather that in front of it I think the soldered aux out cable will be removed. It is causing an issue with the main board not mounting correctly to the tablet housing, and the hardware buttons are not lining up correctly. A standard cable running from the headphone jack to the aux in on the aftermarket cd player will be used as it will all be hidden behind the face plate.
A 3.5mm audio cable was sacrificed today and soldered directly to the aux out connector on the tablet. This worked perfectly, L & R audio + ground soldered to pads big enough for a beginner with an iron (or big enough that an old, worn out soldering iron like mine could easily accomplish the task).
Next step is to install the aftermarket cd player and start testing the tablet aux out/cd aux in. Unfortunately the stock screws holding the factory cd changer in place were over tightened and made of a very soft metal. Most of these screws were stripped and will need to be drilled.
The new 12V to 5V converter arrived and was tested to continually output 5.1V. Two wires were soldered to the DC terminals on the main board (white and blue wires in the main pic.) and run underneath the main board so they could be connected to the converter. These wires were soldered to the converter and coated with liquid electrical tape. The converter was then connected to a 12V power wheels battery and the tablet lived again.
Now that the tablet was up and running a factory reset was performed, then software was installed. I used Tasker (I already owned this software) to prevent the screen from turning off. I also installed ES File Explorer to transfer files from my local network while connected to wifi.
The first voltage converter that I ordered was defective. I tested it (and the newer, working one) by connecting it to my daughter's charged 12V power wheels battery. My multimeter showed 0.0V and after ~3 minutes of testing the converter got so hot that it warped the plastic casing. The item was returned and a new (more expensive, different brand) one was ordered.
As the title says I had an old android tablet (Kocaso brand) that my daughter was using. One morning she brought me the tablet because the back plastic case had popped open. After opening the case I found the internal 3.7V battery had swollen to three times its normal size, and promptly removed it. The tablet still functioned normally with the DC charging cable plugged in even with the battery removed. It was at this time that I decided to add the tablet to my Subaru Baja as a media player (no built in GPS, GSM, or Bluetooth for any other cool car specific functions). Along with the tablet I am also installing a replacemet cd player that has a rear (behind console) aux in port that will be used to connect audio from the tablet to the vehicle's speakers.