Technique to identify USB female port connector positive and negative polarity

The USB port positive and negative position is universal meaning that no matter which company or even Chinese unknown company that manufacture it the polarity is always the same. However for beginners you might have no idea how to identify the female port connector which one is negative or positive.

This technique require a little bit of sacrifice of the an USB cable - but fortunately they are very cheap to get. Some USB cable cost less than $1 and there are bunch of them everywhere in IT store and probably right at home.

Step 1:

Cut the USB cable using scissors and strip the end to allow expose the core wire.





Step 2:

Plug in the USB cable to power source i.e. PC or USB phone charger and then place an LED on the expose cable. If the LED turns on meaning you found the negative and positive of the USB cable. If not just switch the cable the other way and test again on LED. Once you know the polarity of the USB cable you can then find the female USB port connector polarity using this cable.



Step 3:

Take a female USB port connector and a multi-meter. On the multimeter switch it to continuity mode.



Step 4:

Now connect the USB cable to the USB port - use the multimeter to test which end of the USB female port connector connected to which USB cable. Since you already know the positive and negative of the USB cable in step 2 - it is easy to identify the positive and negative of the USB female port connector by testing which cable of the USB connected to which pin of the USB port.