Chapter 4 81
Undetermined Problems
Undetermined problems are those for which diagnostic tests cannot identify the cause. This may be a failure to
detemine which adapter or device failed, which installed device is malfunctioning, a short circuit is suspected,
or when the system is inoperative.
IMPORTANT: Verify that all attached devices are supported by the computer, and that power supply to the
computer is good.
Follow these procedures to isolate the failing FRU (do not isolate non-defective FRU).
1. Shut down the computer.
2. Visually check the failing FRU for damage. If any problems are found, replace the FRU.
3. Remove or disconnect all the following devices:
t Non-Acer devices
t Printer, mouse, and other external devices
t Battery pack
t Hard disk drive
t DIMM
t Optical drive/diskette drive
t Cards in the ExpressCard/54 and card reader slots
4. Power on the computer.
5. Determine if the problem has chang ed.
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 FRU one at a time. Do not repl ace a non-defective FRU:
t System board
t LCD module assembly
Acer TM 4520 SG.book Page 81 Friday, June 22, 2007 5:43 PM