USB don't provide power?

  • Thread starter Thread starter Zybex
  • Start date Start date
Z

Zybex

A friend's pc with ECS mainboard seems to not provide power to usb ports!!!
First was all ok, but recently scanner stopped to work.
This scanner do not have a separate power supply, gets power from USB and
now works only with others PC.
Seems to work only peripherals with indipendent power supply, others are
simply ignored!
I really do not know if ports are damaged. Plaese, send me your opinion.
Thanks.
 
A friend's pc with ECS mainboard seems to not provide power to usb ports!!!
First was all ok, but recently scanner stopped to work.
This scanner do not have a separate power supply, gets power from USB and
now works only with others PC.
Seems to work only peripherals with indipendent power supply, others are
simply ignored!
I really do not know if ports are damaged. Plaese, send me your opinion.
Thanks.
Click to expand...


Assuming the friend wasn't messing around inside the case,
potentially changing or dislodging the jumper(s) for USB
power, the circuit might've been fried... ECS tends to skip
a few corners now and then.

You might take a multimeter and get voltage readings on the
port's power pins (google will find the pinout, or
http://www.starmount.co.uk/usb_skta.gif ). If there's no
power on the port then trace the power circuit backwards
visually, and with the multimeter. Or, replace the whole
motherboard or buy a PCI USB card.
 
Zybex said:
A friend's pc with ECS mainboard seems to not provide power to usb ports!!!
First was all ok, but recently scanner stopped to work.
This scanner do not have a separate power supply, gets power from USB and
now works only with others PC.
Seems to work only peripherals with indipendent power supply, others are
simply ignored!
I really do not know if ports are damaged. Plaese, send me your opinion.
Thanks.
Click to expand...
USB ports are designed to supply 500ma, (1/2 A), from each port. Most
have a current limiting device which should reset after an overload.
This is usually a very small surface mount device on the motherboard
near the USB port(s). You might look carefully to see if it's cracked
or discolored. Replacement is possible, but takes special equipment.

You can check for +5V at the port connection, usually a red wire to
ports not on the motherboard. Ports integral with the MB are hard to
check without a USB cable with exposed leads because the contacts are so
small and close together. The outside contacts are the power leads.

Virg Wall
 
You might take a multimeter and get voltage readings on the
port's power pins (google will find the pinout, or
http://www.starmount.co.uk/usb_skta.gif ). If there's no
power on the port then trace the power circuit backwards
visually, and with the multimeter. Or, replace the whole
motherboard or buy a PCI USB card.
Click to expand...

another way would be also to bridge +5Vsb line on the ATX MoBo
connector to the power line of the Usb connector, if the power line to
it is already dead & not shorted (to be checked first!) to ground
(maybe some cap dead-shorted) ...
 
kony said:
Assuming the friend wasn't messing around inside the case,
potentially changing or dislodging the jumper(s) for USB
power, the circuit might've been fried... ECS tends to skip
a few corners now and then.

You might take a multimeter and get voltage readings on the
port's power pins (google will find the pinout, or
http://www.starmount.co.uk/usb_skta.gif ). If there's no
power on the port then trace the power circuit backwards
visually, and with the multimeter. Or, replace the whole
motherboard or buy a PCI USB card.
Click to expand...

Another source for identifying the pins on a USB connector (and others):

http://www.hardwarebook.net/connector/bus/usb.html
 
Back
Top