Well I seriously wouldn't guess on where each wire goes, as this can cause permanent damage to your laptop.
I believe you said the wires were Red, Blue and black.
Is there a shield (bare) wire? This wire is usually rapped around another wire or the entire group of wires.
Black is usually (but NOT always) designated as a ground wire, which goes to either chassis ground or the (-) negative side if the supply current.
If this is a switch, one wire would supply a current to the switch, while the other is the return wire from the switch.
Here is where a VOM multi-meter would come in handy.
The meter should be set to either continuity testing or set to the Ohms (resistance) setting.
In these settings, current from the meter's internal battery, flows through one test probe, and into the other test probe, which creates a working circuit, the result, sends a current to the meter's read out.
Depending on if it is a digital LCD read out or an Analog needle type meter, the meter, will read full scale when the current flows 100% through the meter's circuitry.
First thing to do is determine with the meter what the status of each wire coming from the switch is, with the switch open then closed.
Two of the wires should allow a current to flow through the meter when the switch is on the closed position, of course in the case of your laptop, if this is a switch, when the laptop lid is raised for viewing of the screen, the switch should be in a closed circuit condition, a closed circuit means current flows through the switch.
Find out which two wires are allowing this on-off action to happen.
If the red and blue wires are the two wires which are exhibiting this action, we now need to determine what role the black wire is using.
Now I see where you mentioned copying the floppy disk's wire pattern, where you are talking about a whole different set of wire color codes here, which is red, black, brown and yellow.
You also mentioned 3 wires originally, which are red, blue and black.
Lets not get confused here, although the only wire I can see being a comparison here is possibly the BLACK wire.
Those wires are POWER wires which supply power to your floppy drive.
A switch usually only has one side of a circuit on it, either positive or negative (depends on the manufacturer's preference). The switch makes or breaks a circuit, in this case, it would be using one side of the current flow either positive or negative from the power supply, but NOT both.
So we can not use the floppy diskette drive power wires as a comparison here.
Now once you have determined the switches functions, along with which wires are used to send a signal to the switch and which wire sends the return current flow, we have to determine the status of the connector pins on the motherboard.
We can easily find the chassis ground pin, by again having the meter in the Ohms meter range or continuity range.
Placing one probe on a well known circuit trace which is chassis ground and pining out each pin on the motherboard connector, you should find one or two pins which has a 100% full scale reading (also called infinity).
You have now found the motherboard's ground pins or pin and can now label this pin/s as chassis ground.
One of the 4 motherboard pins is the supply pin, without power supplied to the motherboard, this would be hard to determine of course, but if you could power up the device safely, you could put the meter into the DC volts reading, place the BLACK (negative) probe onto chassis ground, then pin out the remaining 3 or 2 pins to find the (+) Positive pin.
This pin (if Positive IS USED through the switch) is the supply pin, it is supplying current to pass through the switch when it is closed.
The last remaining pin, would be the return pin, this is the one where the current flow through the switch is returned to the motherboard and the circuit is completed when the laptop lid is opened fully for screen viewing.
Since I see where you said you have some computer repair knowledge, this theory should be easy for you to follow pretty easily.
Please keep me updated and good luck.
added a few left out words for better clairity.
Edited by MrBruce1959, 26 December 2010 - 01:17 PM.