MiTAC 7521 PLUS/N service manual 124

7521Plus / N N/B MAINTENANCE

8.9 USB PORT TEST ERROR

An error occurs when a USB I/O device is installed.

USB TEST ERROR

1.Check if the USB device is installed properly.

2.Confirm USB driver is installed ok.

YES

Test	Correct It.
OK?
	NO

Board-level

Troubleshooting for

USB test error

Check the following parts for cold solder or one of the following parts on the mother-board may be defective, use an oscilloscope to check the following signal or replace the parts one at a time and test after each replacement.

Try another known good USB device.

	YES
Re-test		Change the
		faulty part
OK? NO
		then end.

Change M/B or go into board-level Troubleshooting.

Parts:

U24, RP21, CP7 F502, R20, R19 C506, L2, C14 F503, R22, R23 C507, L6, C25 R141, R140, R142 R143, , L12

L8, L504, L511

Signals:

USBP1- USB_B1 USBP1+ USB_B2 USBP0- USB_B3 USBP0+ USB_B4 D/USBP1- USB_A1 D/USBP1+ USB_A2 D/USBP0- USB_A3 D/USBP0+ USB_A4 USB_OC0# USB_OC1#

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