I started a small project to build a custom USB-male to female-barrel connector so that I can use any slim USB external cd-rom/dvd-rom device without the need of an external power supply.
Luckily, the X41 comes with such a special connector for a proprietary unit, however, that unit costs over $200 because of the IBM (today Lenovo) name. So I decided to try and build my own.
It’s basically an almost full USB port, it has only 3 pins not 4, but all the pins align in the same distance from each other as they do in a regular USB male 4-pin plug, so I know I can use my dremel to take a regular USB male plug and just shave it down one pin length.
So here is my problem, does anyone have a schematic or know what these 3 pins do?
Are they somehow proprietary to the drive that IBM used to produce as the only drive with their power requirements to run?
I used a multimeter and tested out that one of the pins gives a constant 3v of charge, whist the other two showed nothing, just zero. Also assuming one is ground and one is known now to be the 3v line, whatâ€™s the third pin for?
Lastly, even with the 5v that the top 4-pin line provides, and the 3v that the bottom 3-pin line provides, that doesn’t add up to the 12v I would need for most devices… did IBM cheat somehow?
If anyone can provide any insight or help on this, it will be greatly appreciated.