Acer TravelMate 4220 TravelMate 4520/4220, Extensa 4420/4120 Service Guide - Page 91

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 changed. 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 replace a non-defective FRU: t System board t LCD module assembly Chapter 4 81