I have just recived a new product and I want to replace the permanent USB cable that is soldered to the board with a shorter female end USB. The problem is that when I disassembled the item I saw that the cable is soldered to 5 points to the board using 5 cables that come out of it. Now as far as I know USB 2.0 Type A has only 4 pins (Voltage, Data-, Data+ & GND).

How can I then connect it (The 4 pin female end USB) and why does it have 5 pins when on the other end were it connects to the computer it is a type A connector.

The board

  • 1
    \$\begingroup\$ One of them is the cable shield. \$\endgroup\$
    – Lior Bilia
    Commented Mar 30, 2021 at 15:00
  • \$\begingroup\$ The 5th one could be the shield. If you have a multimeter then you can check if one of them is connected the outer metal case of the Type-A connector. \$\endgroup\$ Commented Mar 30, 2021 at 15:09

2 Answers 2


Since the product came with standard USB type A plug, the fifth wire would be connected to the metal chassis frame shield of the connector.

  • \$\begingroup\$ But why? Is it how to OTG works? \$\endgroup\$
    – Twins96
    Commented Mar 30, 2021 at 17:36
  • \$\begingroup\$ No, USB-A has no OTG. Standard USB will have five conductors between connectors, VCC, D-, D+, GND, and shield. \$\endgroup\$
    – Justme
    Commented Mar 30, 2021 at 17:51
  • \$\begingroup\$ So why is there a connection to the shield? What is its purpose? \$\endgroup\$
    – Twins96
    Commented Mar 30, 2021 at 18:04
  • 1
    \$\begingroup\$ That would be another question, but in short, to connect the metal cases of two devices first to equalize their potential, so that there is no electrostatic discharge from data or power pins, and then the shield prevents electromagnetic radiation from affecting the data bus and also prevents the data bus from transmitting electromagnetic radiation. \$\endgroup\$
    – Justme
    Commented Mar 30, 2021 at 18:29
  • \$\begingroup\$ @Twins96, why would you bring "OTG"? How it is difficult to get a DMM and verify/check all connections? \$\endgroup\$ Commented Mar 31, 2021 at 4:11

The 5th pin is the ID (or "sense") pin.

Look HERE.

It's purpose is to select which device is host and which is slave. This is often called OTG or On-The-Go.

Here is an example. The type-A connector is on the right.

enter image description here

  • \$\begingroup\$ There's no ID pin on a Type-A plug. The OP states that the cable has a Type-A connector, not a Type-B micro. \$\endgroup\$ Commented Mar 30, 2021 at 15:07
  • \$\begingroup\$ That is expected for OTG, yes. Please see the diagram I added. \$\endgroup\$ Commented Mar 30, 2021 at 15:08
  • \$\begingroup\$ OK, but if it is connected to the board then were is it conncted to at the other end were the USB connector is? \$\endgroup\$
    – Twins96
    Commented Mar 30, 2021 at 15:10
  • \$\begingroup\$ Almost surely connected to the ground pin, at the connector itself. \$\endgroup\$ Commented Mar 30, 2021 at 15:11
  • \$\begingroup\$ Check it with an ohmmeter to be convinced. \$\endgroup\$ Commented Mar 30, 2021 at 15:12

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.