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The Personal Pi - Part #1

Blog entry posted in 'The Personal Pi', Jan 10, 2014.

Greetings, everyone!

This is a project that I decided to do just for the heck of it. I had an older portable DVD player lying around that had a blown battery, so I decided to give it new life. Originally I had planned to convert it into a portable game console with the PlayStation 2 (which I also have lying around--can't remember why), but I never use game consoles. I eventually decided that converting it into a personal computer would be much more fun and would actually be useful to me. So here it is--The Personal Pi!

I began with an older Digital Labs portable DVD player. I chose this one because the case is fairly bulky, which gives me plenty of room to work with on the inside. It also has an AV In jack, which will allow me to connect the RPi via the composite video and headphone outputs.

I plan to keep the A/V IN jack and maybe the DC-IN and headphone jacks, but that will depend on how everything goes together. The coaxial, A/V OUT, and line select switch will all probably be removed, and the switch replaced with jumpers to keep it permanently set to "IN". Positioning the switch to "OUT" sets the video source as the built-in DVD player, which I will be removing.

The first step was to remove the screen, driver board, main board, and front panel board from the case. After removing a few rubber covers I was able to gain access to all the screws to remove them. I was surprised that the important part came out in all one piece.

It didn't occur to me until later that I could have left the screen inside the case. Originally I wasn't planning to keep the case (for the Portable PlayStation project) and I disassembled it before I decided to build the Portable Pi instead.
It is not shown in the image, but I also removed the DVD assembly and the top buttons from the case, since I won't be using them at all.

Next is a close-up of the A/V IN jack, which is one of the most important parts of this project.
I somehow had to determine the pinout of the jack so that I'd be able to connect the Pi to it properly. However, when a Google search didn't turn up any useful information, I decided to determine the pins manually using my digital multimeter and an A/V cable. I began by plugging the cable into the jack and set my DMM to the continuity/ohms function.
By plugging the cable into the jack, I had direct access to the color-coded RCA plugs and the pins on the board. I measured the resistance between the center post of the red plug and all of the jack's pins on the board to determine which it connected to. I repeated the process with the center post of the white plug and yellow plug, and also the outer shield of all three. Since the outer shield is ground, they are all connected together and thus share a pin on the PCB. I marked (with a little difficulty due to the solder mask) which pin connected to which plug using W, Y, R, and G for "White", "Yellow", "Red", and "Ground".
There you can vaguely see the letters written on the PCB.

Before I could continue I had to power it up to make sure it still worked. Since the actual battery had exploded some time ago, I looked for and found a 12-volt SLA battery (originally from an old electric weed-eater) that I connected to the DC jack pins. 12 volts was a little more than I wanted to use since it's designed for between 7.5 and 12 volts (and the battery was actually 12.44 volts) but I figured it shouldn't hurt it too badly to go .44v high. Anyway, I connected power and switched it on, and the screen fired right up. So far so good!

Part 2 will cover the actual modifications to the PCB.

Thanks for reading, and please feel free to post a comment!

Proceed to Part #1.5 -->