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The MP3-machine

This is my mp3-machine:

People who have seen a bit more of my website probably recognize it as one of the Acer WT-300s I managed to run Linux on and then tried to cluster together. These devices work as a nice MP3-player too: they run without any moving parts and use only about 10 watt of power. The VFD in the front isn't a normal accessory for these devices, by the way, it's the result of another project I did.


This is the inside of the device. It's basically a small motherboard which includes everything needed to run the device. It only needs an external power supply of 12VDC at about 1 amp to do its job. The VFD is soldered to the internal +5V-rail and the serial port before the MAX232-like IC: that saved me an extra chip.

And this is the CD-player-module it all has to fit in. Luckily, there's enough space for this to fit, so there are no shenanigans needed like the mobo poking out of the front of the case here.

Affixing the motherboard to the case wasn't that hard, drill holes, take some long screws and a few nuts and the mobo stays in place. What was a bit more difficult was where I could get the power. Just recycle the PSU I used to power the device with would be an option, but according to the service manual of the set I already had 2x24VAC@1amp coming into the device via the ribbon cable, I couldn;t let that go to waste, so I made a quick-and-dirty 24Vac->12Vdc-pcb using an integrated switching power regulator and some parts. The circuit is completely out off the app note for the switching IC, so no surprises there.

On to the display. The original display was an LCD backlit by a set of lamps contained in plastic white light-spreaders.

The lightspreader would be useful as a montaging aid for the VFD, or so I thought. I miscalculated the width of the VFD by a few mm, but hey, with a few dabs of glue it fits great and nobody will see the crookedness of the construction from the outside.

Meh, good nuf.

And with the front re-assembled and the cover for the CD-tray glued in place, this is how everything looks:

Damn, these plastic parts on the side of the vfd are butt-ugly. Now, how can we fix these... Ducktape to the rescue!

Much better. (The part that lights up in the photo is an internal metal part of the VFD, no plastic.)

Because I've put the mainboard of the WT-300 in the case rotated 90 degrees, no I/O is accessible from the back. That's no problem, with one exception: the network port should be available to plug the device into the network. I decided on making a small extension cable for that, built from a cut-off network cable and a RJ45-jack desoldered from an old network card. To make the thing accessable, I decided to hack up the AM-antenna-connector of the original tuner-part to hold the RJ45-connector:

And after a bit of work with the multitool, it looked like this.



And after a few last things (a. o. connecting the ribbon-cable to an internal usb sound-card), the mp3-player was ready for use. The internals look a bit messy, but hey, that's what cases are for, aren't they?

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