There is only one magnet at the flap and its quite strong. So, this is another reason why you need to close the flap with your other hand and not 'flip' it like a communicator. Once the flap is about less than 1cm to closing, the magnet will start to attract and activate the reed switch. And since the reed switch is metal, the magnet will try to pull the whole flap onto the body. So, if you do not use the other hand to control the closing, you will hear a very unpleasant clunk and if you do it more often, it might chip the paint. And remember, magnets do lose their power though shocks and heat.
Just to light the LEDs at the flap, there are 3 volts going through the hinges, just as I suspected. I am using the same idea with my Playmates STNG Tricorder but if I want to do this on the actual prop, I would have problems because my design needs 4 wires.
The reed swicth is located at this area (where the button magnet is) and you can activate the Tricorder this way. It was fun until I accidentally held it alongside with my Nokia 5800 case which also has magnets. You know what happened next. Oh, and if you have a magnet, the reed switch is pole sensitive. One pole switches it on, the ohter switches it off, all at the distance of 1cm! This also explains why the closing rachet sound is delayed because the Tricorder was designed to read from the only single reed switch. In other words, it will play the closing rachet sound after the reed switch is closed (or about to be closed, depending on whose point of view). This also explains the strong magnet as they want to influence the switch from a far distance. And this has nothign to do with closing the flap faster or slower. Putting a second reed switch would solve the problem but then, you need a second magnet at the flap which must also be isolated from the first magnet and also it must not affect the main reed switch as well. So, the closest would be at the left side of the EMRG panel.
Coming back to the flap detail; Closing the flap of the Tricorder would generate the rachet sound even when it is 'OFF' would mean that the Tricorder is usng battery all the time and the flap closing action might not be the main turn off switch. Anyway, I will test this theory for a week and we'll see.