Hein (fub) wrote,

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MACH F: DVD status LED

Remember when I changed the power- and HDD-LEDs on the MACH F to red ones? I wrote that I wanted to change the status LED on the DVD-ROM to a red one, but that the prospect of fiddling with an SMD printed circuit intimidated me.

Today, I wanted to install the serial card and the display itself. It turned out that I had to get the DVD-ROM out of the case in order to do that, so I decided to take a peek at the innards of the thing -- I had some red SMD LEDs lying around specifically for this purpose. No time like the present, eh?

When you unscrew the underside of the drive, this is what you see. The front of the drive is to the right. The PCB is divided into two parts: the back part contains the controller and various other circuitry. You can see the actual drive mechanics in the middle, and at the front is a smaller PCB that contains the 'interface' with the user.

The large chip has some sort of rubber stuff glued on it -- probably for the heat transfer to the underside of the drive. It's a pity you can't see the type number of the chip.
The smaller chip to the left of the large controller is a flash chip, probably for containing the firmware and stuff like region encodings.
Above that is another controller chip. Again, no type number discernable (the underplate of the drive has the thermal transfer rubber at that position), but I am guessing that it is the chip that controls the motor movements, based on its position.
At the underside of the photo, you can see the 40 soldering points where the IDE connector is. To the left of that is the power connector, and to the right you can see some of the connectors for jumpers.

The drive unit. The copper-colored part can move up and down -- the screw-like rod to the right is used for that. The blue 'thing' is the connection of a ribbon cable that is attached at an angle, so that it moves along with the copper-colored part.

The front of the DVD-ROM, with the cover off. From left to right: the headphone jack, the volume control, the status LED, the eject-motor (you can see a rubber band running from the top of the motor to a larger wheel) and the eject button.
When I saw this, my heart jumped: the status LED is not SMD, but a low 5mm LED... In fact, it looked suspiciously at the high-powered, large-angle LEDs I got this januari...

I desoldered the original status LED and put it on a scrap piece of circuitboard. Then I added a red LED next to it. They're the same size, but the red LED has a larger viewing angle...

...and is slightly brighter. That doesn't matter much -- the light is 'transported' by a clear piece of plastic to the front of the drive, so most of the light will simply be blocked by the front of the drive.

The front PCB with the red LED in place. Quite a neat PCB, and for some reason the star at the upper right of the PCB amuses me greatly. The PCB is connected to the main PCB with a ribbon cable, and held in place by two plastic clasps -- that's what the two square holes are for (on either side of the motor).

The assembled DVD-ROM in action! The light is quite a bit brighter than with the original status LED, but that doesn't bother me overly much.

I discovered a defect with the MACH F display, though -- the exact same defect I had earlier during development. This warrants some further investigation, so no display photos yet!
Tags: led, mach f

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