Personal Pi - Part #2

Hello everyone!

I finally made some progress on the Personal Pi project, so here's an entry documenting what's happening at this point.

I left off in Part #1 by marking the PCB showing which pin connects to video and which pins connect to left and right audio. The first thing I did today was to remove the A/V In connector from the PCB in the portable DVD player. This would give me access to the pins from the inside, since I will not need to connect any external equipment via the jack.
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I then placed the screen and PCBs back into their proper places in the DVD player to make sure I didn't put something where a main board had to go. Once everything was put back together, it was time to figure out where the Pi was going to go. This turned out to be trickier than I had originally expected. The idea was to make the Pi removable, so I needed to be able to fit RCA video and 3.5mm audio cable connectors into the case. This proved to be more difficult than originally expected. After about 15 minutes of tweaking and turning the Pi, I finally found a location that would work fairly well that would allow the USB and ethernet ports to face outward towards the sides.
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Unfortunately, in order to fit it in the area meant I'd need to remove two support posts, circled in red in the image.
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I didn't have my Dremel with me, so I took a knife and a pair of pliers and simply cut them out. Thankfully they came out very easily without damaging the surrounding case. I was then able to fit in the Raspberry Pi, though I will still need to cut out an opening in the side for the USB and ethernet ports. This did, however, make it easier to see where the Pi will eventually be located within the case.
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As mentioned earlier, I want to be able to remove the Raspberry Pi if necessary without having to desolder anything. This meant I would need to use a 3.5mm audio cable and an RCA video cable to connect the DVD player board to the Pi. I found an older audio cable (from a pair of headphones) that had separate wires. I wouldn't use a cable from a modern set of headphones because the wires are extremely thin and have an enamel coating, making it nearly impossible to solder them. I also found a video cable with an RCA plug for the video.
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I connected both cables to the Raspberry Pi and placed the Pi in its place so that I could cut off the wires at the required length.
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I decided to solder the video cable to the board first for testing purposes, to make sure the Pi could, in fact, display on the screen using the existing circuitry. I decided to do a quick solder job to connect the cable to the DVD player PCB. It was nothing fancy, but I just had to be sure that it would work. I soldered it up, connected a homemade 12 volt power supply to the portable DVD player, plugged in my keyboard/mouse dongle into the Pi, and then connected power to the Pi.
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Nothing. No video, but I heard a horrible sound coming from the built-in speakers. I hadn't connected the speakers yet (or so I thought), but I had heard the sound before--it's what you hear when you connect the video cable into an audio in. I desoldered the video cable and touched it around the different pins of the old A/V In connection on the PCB. I eventually found where it was supposed to be connected. Apparently the steps described in my first blog post to determine which pin was which were flawed. I soldered the video cable to the board, reconnected everything, and applied power to the player and then to the Raspberry Pi.
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Success! The Pi desktop appears on the DVD player screen! The video quality is poor, but is definitely usable.

Now that I know it works so far, I'm going to end this entry and pick the project up again in my next one. In my next entry I will finish connecting the video and audio cables, cut holes in the side for the USB and ethernet ports, mount the Pi, and hopefully put the whole thing together again.

Thanks for reading! Unfortunately I am somewhat distracted tonight so my writing isn't very good, but I hope you enjoyed this post. As always, feel free to post a comment or question if you have one!

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