The case for the mp3 player

Note: You can click on each image to see a larger one!


dcp_2637.jpg

This is the CD player that I got quite cheap through an eBay auction. It's a Sony CDP-591. Other brands and models would probably work as well, provided that the case is large enough and has all the buttons you need. However, I preferred a Sony one, because my "real" CD player is a Sony CDP-415, which is almost the same as the -591, but with optical SPDIF output and slightly different buttons. So I knew what it would look like and that everything would fit nicely. Furthermore, I can keep the innards of the player, in case I need some spare parts for my real CD player.

Oh by the way, the player from that auction was declared "faulty", it wouldn't play any CDs. That's why it was so cheap. Of course I didn't care, I just needed the case, and the seller confirmed that the case was OK and without big scratches or things like that. When I got the player, I just couldn't help myself and tried to fix it. I opened the case, removed dust and dirt, cleaned the lens, and lubricated the motor track and gearwheel. Much to my surprise, that was indeed sufficient to fix it. It started playing CDs without any problems. I seriously considered selling it again as a working CD player on eBay, which would have made me quite some profit, I guess. But then again, I'd still need a case for my mp3 player.

So I started taking the player apart. It kind of hurted me inside. I hate destroying things that work. *sigh*


dcp_2641.jpg

Here you can see the LCD display that I intend to build into the player. The photo shows that it should fit inside, in place of the original display, behind a semi-transparend red cover. I'll have to do a bit of tweaking, though.

The LCD display is a monochrome graphic display with a resolution of about 128 64 pixels. It also has a nice backlight. It has a parallel interface, so I can easily connect it to the parallel port of the mini-SBC. The display allows for pixel-wise addressing, so I can display anything I want, including text in various self-made fonts, a nifty GUI (an X Window driver, anyone?). Maybe even CD inlay/cover images, although they probably don't look very good on a monochrome display. The display doesn't do greyscales, it is only pixel-on or pixel-off.


dcp_2645.jpg

This is a close-up of the right part of the player's front side which carries all the buttons. As you can see, it has 40 (yes, fourty!) buttons, not counting the open/close button. That's enough for plenty of functions.


dcp_2646.jpg

I made this photo for size comparison. On the right you can see the power supply, on the left there's the casing of the mini-SBC. Both have about the size of a 3.5" disk drive. It is clear that they should fit into the CD player case without any problems.


dcp_2647.jpg

Another size comparison. If I put the two babies beside each other, there would still be enough space to add a CD-ROM drive on the left. (Note, however, that I don't plan to add a CD-ROM drive into the game for now. I'm only playing mp3s from the network, i.e. from my file server, but not from CD.)


dcp_2648.jpg

Yet another size comparison. If I put them back-to-back like on this photo, there would be even more free space for additional stuff like a CD-ROM drive or harddisks.


dcp_2651.jpg

I removed the cover to look at Sony's innards. It looks quite tidy and makes me wonder why they used such a large case for the whole thing. The stuff inside would have fit into a case of half the size. Well, OK, maybe it's because of the display and all the buttons. I certainly don't mind.


dcp_2660.jpg

This is about 60 seconds later. Plenty of space to put things into. Note that you should keep the front cover from the CD tray. You don't want to have a hole in the front of the player. Also, if you add a CD-ROM drive into the player, you can glue the original Sony (or whatever brand you have) cover to the front of your CD-ROM drive's tray.

Basically, you have to be very careful when taking the player apart. Don't just throw things away, you might need them later! This also includes the PCBs behind the front of the player, which carry micro switches for the buttons, the headphone socket, the volume knob and other things. You will probably want to re-use them.


dcp_2661.jpg

Well, the photo speaks for itself. The mini-SBC box and its power supply fit nicely into the case.


dcp_2662.jpg

Even better: If you omit the upper cover of the mini-SBC box, you can even put it on top of the power supply. That means that you have really lots of space left. In theory, you could easily add a CD-ROM drive and two harddisks.

Omitting the upper cover of the mini-SBC box might be a good idea anyway, to improve air flow within the player, thus better cooling of the CPU.


dcp_2652.jpg

This is a photo of the front side of the player which carries all the buttons, made from the inside. You can see the green PCB which is affixed with red screws (no, this is not some kind of red-screw effect on my camera, but the screws are really red).


dcp_2658.jpg

This is a close-up of the previous one. Sony kindly drew black squares on the PCB for every micro switch that's connected to a button on the front. This makes locating them very easy. You can see that the conductor paths roughly form some kind of rows-and-columns scheme, like is commonly done in PC keyboards. This should make it quite easy to connect the PCB to an old keyboard controller board which we can connect to the PS/2 port of the mini-SBC.


dcp_2659.jpg

An even closer close-up. Don't you love digital cameras with a macro lens ...


dcp_2663.jpg

This is the controller board from a PC keyboard that I intend to use to connect the buttons of the player case to the mini-SBC. On the photo you see the connectors for the rows (on the left) and for the columns (on the right).

There are also the usual three keyboard LEDs (num lock, caps lock, scroll lock) which might be useful for something, too. For example, the num lock LED could be used as some kind of "busy" indicator during booting, because the BIOS can be configured to enabled num lock. Once the operating system has been loaded and is ready to run our "firmware", we can switch off that LED by software.


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