Acer Aspire S7-391, Service Manual, Page: 146 / 186

4-18 Troubleshooting
Intermittent Problems
0
Intermittent system hang problems can be caused by a variety of reasons that have nothing to
do with a hardware defect, such as: cosmic radiation, electrostatic discharge, or software
errors. FRU replacement should be considered only when a recurring problem exists.
When analyzing an intermittent problem, perform the following:
1. Run the advanced diagnostic test for the system board in loop mode at least 10 times.
2. If no error is detected, do not replace any FRU.
3. If an error is detected, replace the FRU. Rerun the test to verify that there are no more
errors.
Undetermined Problems
0
The diagnostic problems does not identify which adapter or device failed, which installed
devices are incorrect, whether a short circuit is suspected, or whether the system is
inoperative.
Perform the following procedures to isolate the failing FRU (do not isolate non-defective
FRU).
NOTE:
NOTE
:
Verify that all attached devices are supported by the computer.
NOTE:
NOTE
:
Verify that the power supply being used at the time of the failure is operating correctly.
1. Remove power from the computer.
2. Visually check the components for damage. If any problems are found, replace the FRU.
3. Remove or disconnect all of the following devices:
 Non-Acer devices
 Printer, mouse, and other external devices
 Battery pack
 Hard disk drive
 PC Cards
4. Apply power to the computer.
5. Determine if the problem has changed.
6. If the problem does not recur, connect the removed devices one at a time until failing FRU
is found.
7. If the problem remains, replace the following FRUs one at a time. Do not replace a
non-defective FRU:
 Mainboard
 LCD assembly