Hey guys, this wont be the most fancy fan installs you have ever seen but it definitely works.
I was fixing a friends xbox and I decided to do something about the heat issue while I had it apart; i wanted to add a fan where it would help. The place I decided was on the top side of the xbox, that would go in front of the CPU and directly over the heat sink thats extended from the graphics card.
I wanted to power this fan with a constant 12volts; the stock fans have variable voltage so i didnt want to use that. I also decided, if possible, wanted to avoid an external power supply for the fan. I probed all of the power connections when the xbox360 is on and found that there is a 12v power supply on some of the pins.
The reason why I did this is because of the constant 12V supply and there was a residual voltage level at around .22 volts when the console was off. I wasnt sure if this would do anything to the fans so i built this circuit to block any voltage until the console was turned on. Also, if I add fans later, I dont want to put too much of a load on the factory fan power supply circuit; im not sure how much current it can handle.
Since the factory fan's voltage supply is variable, I decided to use a transistor switch circuit to use the stock fan power supply as a NPN transistor's "turn on voltage". Here is the drawing of the circuit i made:
I set out to find which pins, and where i can solder a wire to "tap" into that 12v. I found it on the voltage regulator(i think thats what that is); i soldered the wire to the leg which was connected to the 12V trace:
Now I have to tap into the stock fan's power supply for the transistor's turn on(base current). I just ran a wire through where the factory wires connect and soldered the wires there. This exact picture isnt the factory fan but it is exactly the same in the way how you hook them up to the fan's connections:
Now to soldering the circuit together and mounting it somewhere. I soldered the transistors, resistors and wires to a small board and then cut it down to size; its pretty small. Because plastic is a good insulator; i screwed the little circuit to the air shroud. The wire coming out of the white shroud is the 12V wire. The wires look like a mess but it was straightened out before this project was finished.
Now, I cut a hole in the console's casing to mount the fan. I used this with metal cutting scissors and a Dremel tool to cut the plastic but there were no real fancy tools used. This is the wires to the fan getting soldered to the fan. not shown in this picture but I twisted the fan's power/ground wires before i soldered them and ran them along the side of the case:
This is the final product. I used a case fan from a computer case:
This is very basic obviously but it has worked well so far. I was going to make this fan with a variable speed knob but this is not necessary; the fan, compared to the DVD player's noise, is silent.