Lenovo 20QT, Hardware Maintenance Manual

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Undetermined problems
If the diagnostic tests did not identify the adapter or device that has failed, if wrong devices are installed, or if
the system simply is not operating, follow these procedures to isolate the failing FRU (do not isolate FRUs
that have no defects).
Verify that all attached devices are supported by the computer.
Verify that the power supply being used at the time of the failure is operating correctly. See “Power system
checkout” on page 28.
1. Turn off the computer.
2. Visually check each FRU for damage. Replace any damaged FRU.
3. Remove or disconnect all of the following devices:
a. Non-ThinkPad devices
b. Printer, mouse, and other external devices
c. External diskette drive or optical drive
d. Wireless cards
4. Turn on the computer.
5. Determine whether the problem has been solved.
6. If the problem does not recur, reconnect the removed devices one at a time until you find the failing FRU.
7. If the problem remains, replace the following FRUs one at a time (do not replace a nondefective FRU):
a. System board
b. LCD assembly
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P1 Gen 2, X1 Extreme and X1 Extreme 2nd Hardware Maintenance Manual