Announcement

Collapse
No announcement yet.

USB Hub problem

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • USB Hub problem

    I have a 7 port powered USB hub in the front of my car, the computer is in the back. I ran the 5v connection from the M2-atx power supply to run the power but for some reason it seems like its not enough amperage to run an external cd rom from it. The power supply does have some bulging capacitors on it so Im assuming thats why? The external should work as long as the usb hub is powered correct?

  • #2
    USB Power

    It is possible that your external CD ROM actually requires an external power source even though the power connecter is a USB plug.

    Does your CD ROM have two USB connectors? If so one is data and the other is power. You would need something like this to provide power http://www.amazon.com/Gilsson-Univer...4799502&sr=8-2

    I hope this helps.

    Comment


    • #3
      The external works fine If i plug it directly into the machine without the hub.

      Comment


      • #4
        any other ideas?

        Comment


        • #5
          You could be seeing a voltage drop on that run from the back to the front of the car. You may want to check the voltage at the hub.

          If possible, take the hub and connect it to the power supply with a short cable and see if your CD works then. If so, you might need to get a point-of-load power supply.

          Comment


          • #6
            i used a multimeter to check the voltage that was fine. but it wasnt able to check the amperage so i bought a new multimeter and im going to check that next.

            Comment


            • #7
              i tested the amperage and it was drawing between 500ma and 1.2 amps, i think thats fine. should i just try to power the cd rom directly? or could it just not like a usb hub

              Comment


              • #8
                I'd suggest you power the hub through its (separate) 5V connection.

                The hub absorbs some power and may limit each port (current).
                The usb spec is 500mA but maybe that means "at least"?. Hence the PC whatever might supply 500-1200mA.

                Usually hi-current devices use 2:1 usb connector - ie, for a 1A device, 2 from the PC for 500mA each into one usb into the device.

                Comment


                • #9
                  ya but the power supply is able to supply 8amps on the 5v line i figured that should be plenty no?

                  Comment


                  • #10
                    8 Amps for a 1.2A load.... I suspect that is enough.

                    So either the hub is limiting port current, or the cable from the hub is too long...

                    Comment


                    • #11
                      The cable from the computer to the hub should be no more than maximum 5 meters. That's the maximum signal length specefied in the USB 2.0 documentation.

                      Have something to to about low current and signal noise.

                      Comment


                      • #12
                        500mA is the maximum per port on a USB 2.0 externally powered hub. The PC ports can supply 1A or more. That's why it works that way. Just tap into that supply and power the drive if it has a barral connector or a USB Y if not. It will work fine.

                        Comment


                        • #13
                          Originally posted by Curiosity View Post
                          500mA is the maximum per port on a USB 2.0 externally powered hub. The PC ports can supply 1A or more. That's why it works that way. Just tap into that supply and power the drive if it has a barral connector or a USB Y if not. It will work fine.
                          gotcha, ill throw that around, due to the lack of space in my dash i had to solder the usb cable directly to the circuit board inside the external drive, so either ill add a power cable, or maybe ill solder a Y USB cable instead.

                          Comment

                          Working...
                          X