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01-01-2009 05:08 PM - edited 01-01-2009 08:31 PM
Issue : Webcam is not detected in device manager or any of the webcam related applications.
Frequency: Sometimes or Always
OS: I believe this issue does not depend on the operating system used.
- The webcam is connected via an internal USB port, which is connected to some internal hub. Depending on your laptop model, this hub could be shared with the external USB ports on your laptop.
- Each USB device requires a certain amount of power (measured in current in device manager) in order to run, my webcam requires 500 mA
- When there is not enough power for all the devices, the computer automatically turns off one of the devices.
- At system startup, there is no OS to determine who gets more power, so it must be the BIOS/usb controller.
- The BIOS or usb controller must determine who to turn on, beucase it must detect USB keyboads and hard drives while starting up.
1. USB Power distrobution Problem
Upon system startup, IF there are any devices connected to the ports which are on the same interal hub as the webcam, for some reason or another even if the device takes very little power, the USB controller turns off the webcam in order to provide for the connected device.
- Try disconnecting all USB devices then starting up the computer, if the webcam then shows up consistently, the problem has been found.
- If you still want to use that device try connecting it to the other side the laptop. On my laptop it seems the USB ports on the right and left are seperate.
- If the problem causing device is a USB hub trying connecting an AC adatper to it (if possible)
If this does not resovle your issue check the next possible cause:
2. Software problem
Normally, even if it there is a software problem the device will still appear in device manager.
- Try updating the firmware in the webcam or the drivers from HP website, you can always compare the hardware/vendor ID from the inf file in the SP to see if it is for your webcam. Most of the SP's for webcams are poorly documented so you never know what SP is for what webcam. If you want the vendor ID and hardware ID and you can't see it in device manager, here are instructions for how to view disconnected USB devices in device manager: http://support.microsoft.com/kb/315539
- Try running ubuntu from a live cd then installing "hardinfo" and then running it from the terminal. If it can detect the camera and windows cannot, then the issue is almost surley software related and a recovery should fix it.
- If you aren't good with linux, then just do a factory recovery after backing up your data.
If the webcam still cannot be detected after these issues, check the next possible cause:
Either the motherboard or camera has some glitch or problem that cannot be repaired by a recovery.
- Send the computer to HP if under warranty, remember they ALWAYS reimage expect maybe for a keyboard replacement. So be sure your data is backed up!! and don't leave any CDs in the drive.
- If you out of warranty it may be better to find an HP certified repair center, and perhaps purchaes the parts from ebay, buying direct from hp can be pricey, for example, the rubber feet on the bottom of the laptop cost 80 dollars for the whole set.
Finally My Personal Expierenece
Laptop : dv9700T CTO
The cause: power distrobution between webcam and an APPLE keyboard (which has 2 usb ports so its a hub too)
Some numbers from device manager:
- Total Power Avalible : 500mA per port
- Webcam uses 500mA
- Apple Keyboard with 3 ports uses 400mA
400 is less than 500 it seems that the controller is confused about the power taken by the hub.
Soultion: Simply connect the USB keyboard to right USB ports, then everything is fine.