The FMC has four LEDs already connected on the grren board and the manual from OpenCockpits describes very well how they are wired. The cables to light the LEDs are available in the 40 pins connector: the ground is common and there is one wire available for each of the four LEDs (However in the picture of the manual there is an error in the way the holes of the 40 pins connector are numbered....)
I preferred not to scrape the gumi of the cables but instead to put another thin cable in the hole before inserting the 40 pins connector in the socket.
Actually, I ended connecting in this way only the LED for the MSG and preferred to wire the EXEC in a different way. The reason is that for the EXEC I had to put a LED with a resistor and, at least for me, there is not enough space for that. I suggest to use a LED with a incorporated resistor for the EXEC. They costs a little bit more but for this specific case I think they are of a great help to reduce the cabling and the space needed for the resistor. I did 2 new holes in the board just below the black BRT pin, as you can see in the following picture of the rear side of the board:
There is enough room for one of the holes but for the second one it is a little bit risky.... As you can see at the bottom of the right big hole there are 2 little holes one close to the other. They are the holes supposed to to be used for this LED and that are wired in the 40 pins connector of the board. The reason I did not use them is because I need to mount the LED in the frame, then put the keys in place and only in the final step to close the box. I need the LED to be moveable and to be able to turn left and right the frame before closing. It might be that I am not skilled enough ;-)
Note that the LED must be connected to a master card or to an output card to be lighted because the FMC as an OpenCockpits key card that has no output lines.
Pay special attention to the position of the keys because is very boring to dismantle the device only for that. And pay attention to the keys also. Each key is composed of two parts: the black upper side with the engraved letter and a transparent squared frame at the bottom. They are simply glued and in my case the glue went banana on its own and I had to fix the pieces again... I hope these pieces are glued well because it is a lot of time to dismantle the device, glue and remount!
I put the FMC into a box. The cable run out of the box from the bottom. The box itself has been fixed on the left side of the monitor. As I said, unfortunately I have no room to build a pedestal. The following picture shows the FMC in its final position:
Theis shows part of the cockpit during a flight:
And the last one shows the FMC during a flight:
As you can see the quality of the image is quite good and the written are placed exactly in front of the left and right keys. Some light comes out of the upper side I have to better seal the frame): it is produced by the screen of the FMC.
Flying a liner with the FMC improves the feeling of the reality so I really suggest you to have one in your home cockpit. The feeling of the OpenCockpits one is quite good. I mean the screen is very good and if I press a key the reaction time is very good.
But is is not perfect. As I said the glue of one of the keys failed without having done anything. The keys are too loose; this is not a problem normally unless you mount the device in a vertical position as I did.
Very good to have the lines to connect the LEDs but why are they in the 40 pins connector together with all the other wires? It would be better to have a dedicated connector considering that they must be connected to an external board.
Finally a couple of words about the missing EXEC LED. IMO the other LEDs are not very important. In the 767LD for example there is an annunciator in the cockpit showing that there is a message in the FMC. But the EXEC LED is really important because it is used very often and it is the only way to know that the FMC is waiting for you to press the relative key.
I consider a big lack the absence of such LED. I appreciate the wiring in the board (even if I preferred not to use).. But where one is supposed to put the LED? And IMO it is very complicated to wire....
Why don't have the LED in the place of the BRT black pin? It is a fake and useles... The best solution would be to have the LED incorporated in the key of course...
We must take into account have to consider the price that is very low compared with other similar devices on the market.