Acer Extensa 4220 TravelMate 4320/4720 and Extensa 4220/4620 Service Guide - Page 119

Undetermined Problems 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. NOTE: Verify that all attached devices are supported by the computer. NOTE: Verify that the power supply being used at the time of the failure is operating correctly. (See "Power System Check" on page 95.) Follow procedures below to isolate the failing FRU. Do not isolate non-defective FRU. 1. Power off the computer. 2. Visually check them for damage. If any problems are found, replace the FRU. 3. Remove or disconnect all of the following devices: K Non-Acer devices K Printer, mouse, and other external devices K Battery pack K Hard disc drive K DIMM K CD/DVD-ROM drive K PC cards 4. Power on the computer. 5. Determine if the problem has been resolved. 6. If the problem does not recur, reconnect the removed devices one at a time until you find the failed FRU. 7. If the problem persists, replace the following FRU one at a time. Do not replace a non-defective FRU. K System board K LCD assembly Chapter 4 109