Chapter 4 81Undetermined ProblemsUndetermined problems are those for which diagnostic tests cannot identify the cause. This may be a failure todetemine 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 thecomputer 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 devicest Printer, mouse, and other external devicest Battery packt Hard disk drivet DIMMt Optical drive/diskette drivet Cards in the ExpressCard/54 and card reader slots4. 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 boardt LCD module assembly
