Question: How can I fix this USB problem? The USB ports on my friend's Dell laptop don't work.  In other words, when I plug in USB devices, like flash drives, they don't function.  (The light on my USB SD card reader doesn't light up, for example.)  I already deleted the drivers and let the computer reinstall them through Plug-and-Play.  The computer recognized the hardware and installed drivers, indicating that it knows the USB device is there, but it still doesn't work.  What else can be done to fix this problem?

Answer: Hi Doc...\n\nWell, if you followed the steps I gave you last time you asked this, then the problem is probably hardware-related. To find out for sure, get a voltmeter, set it to DC volts. \nThe USB interface consists of 4 pins. The two outside pins supply power to the device, and the inside pins are for data. Polarity need not be observed if you are using a digital voltmeter. With the computer booted up and running in Windows, put one lead of the voltmeter on one outside pin of a USB port, and the other lead on the other outside pin. If the meter reads 5 volts (regardless of polarity), then the USB ports are getting power, and the USB hub has probably failed. This problem is a depot-level problem, and only a warranty replacement or costly service will fix it. However... If the voltmeter reads zero, then your 5volt power connector inside the laptop case has probably disconnected. If the machine is within warranty, by all means take advantage. If not, then disassembly will be required. If your next Yahoo Question is "How do you take apart a Dell Laptop" then I will assume that your USB ports failed the voltage check, and I'll go into the disassembly procedures there.
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