IBM ThinkPad R40 2681 Hardware Maintenance Manual

Also see for ThinkPad R40: Special instructions User guide User manual Setup guide Hardware Maintenance Manual

Contents

Intermittent problemsIntermittent system hang problems can be due to a varietyof causes that have nothing to do with a hardware defect,such as cosmic radiation, electrostatic discharge, orsoftware errors. FRU replacement should be consideredonly when a problem recurs.When analyzing an intermittent problem, do the following:1. Run the diagnostic test for the system board in loopmode at least 10 times.2. If no error is detected, do not replace any FRUs.3. If any error is detected, replace the FRU shown by theFRU code. Rerun the test to verify that no more errorsexist.Undetermined problemsYou are here because the diagnostic tests did not identifywhich adapter or device failed, wrong devices are installed,a short circuit is suspected, or the system is inoperative.Follow these procedures to isolate the failing FRU (do notisolate FRUs that have no defects).Verify that all attached devices are supported by thecomputer.Verify that the power supply being used at the time of thefailure is operating correctly. (See “Power systemcheckout” on page 39.)1. Power off the computer.2. Visually check each FRU for damage. Replace anydamaged FRU.3. Remove or disconnect all of the following devices:a. Non-IBM devicesb. Devices attached to the port replicatorc. Printer, mouse, and other external devicesd. Battery packe. Hard-disk drivef. External diskette driveg. DIMMh. CD-ROM and diskette drive in the Ultrabayi. PC Cards4. Power on the computer.5. Determine whether the problem has changed.6. If the problem does not recur, reconnect the removeddevices one at a time until you find the failing FRU.7. If the problem remains, replace the following FRUs oneat a time (do not replace a nondefective FRU):a. System boardb. LCD assemblySymptom-to-FRU indexThinkPad R40 59