Lenovo K4450 Laptop Hardware Maintenance Manual - Lenovo K4450 and K4450A - Page 52

Screw notices, originalFRUbeforeyoucontinue., Tightenscrewsasfollows, tableforeachstep.

Page 52 highlights

• If you are instructed to replace a FRU but the replacement does not solve the problem, reinstall the original FRU before you continue. • Some computers have both a processor board and a system board. If you are instructed to replace either the processor board or the system board, but the replacement does not solve the problem, reinstall the original board, and then replace the other one. • If an adapter or a device consists of more than one FRU, any of the FRUs might be the cause of the error. Before replacing the adapter or device, remove the FRUs one by one to see if the symptoms change. Find and replace only the FRU that changed the symptoms. Screw notices The Lenovo notebook computer uses special nylon-coated screws that have the following characteristics: • They maintain tight connections. • They do not easily come loose, even with shock or vibration. • They are harder to tighten. Do the following when you are servicing the computer: • Keep the screw kit in your tool bag. • It is recommended that you use new screws. • It is recommended that you use each screw only once. • Use a torque screwdriver if you have one. Tighten screws as follows: • Plastic to plastic Turn an additional angle of 90 degrees after the screw head touches the surface of the plastic part. • Logic card to plastic Turn an additional angle of 180 degrees after the screw head touches the surface of the logic card. Notes: • Ensure that you use the correct screw. It is recommended that you use new screws for replacements. If you have a torque screwdriver, firmly tighten all screws to the torque specified in the screw information table for each step. • Ensure that torque screw drivers are calibrated correctly following country specifications. 46 Hardware Maintenance Manual

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•IfyouareinstructedtoreplaceaFRUbutthereplacementdoesnotsolvetheproblem,reinstallthe
originalFRUbeforeyoucontinue.
•Somecomputershavebothaprocessorboardandasystemboard.Ifyouareinstructedtoreplaceeither
theprocessorboardorthesystemboard,butthereplacementdoesnotsolvetheproblem,reinstallthe
originalboard,andthenreplacetheotherone.
•IfanadapteroradeviceconsistsofmorethanoneFRU,anyoftheFRUsmightbethecauseoftheerror.
Beforereplacingtheadapterordevice,removetheFRUsonebyonetoseeifthesymptomschange.Find
andreplaceonlytheFRUthatchangedthesymptoms.
Screw notices
TheLenovonotebookcomputerusesspecialnylon-coatedscrewsthathavethefollowingcharacteristics:
• They maintain tight connections.
•Theydonoteasilycomeloose,evenwithshockorvibration.
• They are harder to tighten.
Dothefollowingwhenyouareservicingthecomputer:
•Keepthescrewkitinyourtoolbag.
•Itisrecommendedthatyouusenewscrews.
•Itisrecommendedthatyouuseeachscrewonlyonce.
•Useatorquescrewdriverifyouhaveone.
Tightenscrewsasfollows:
Plastic to plastic
Turnanadditionalangleof90degreesafterthescrewheadtouchesthesurfaceoftheplasticpart.
Logic card to plastic
Turnanadditionalangleof180degreesafterthescrewheadtouchesthesurfaceofthelogiccard.
Notes:
•Ensurethatyouusethecorrectscrew.Itisrecommendedthatyouusenewscrewsforreplacements.If
youhaveatorquescrewdriver,firmlytightenallscrewstothetorquespecifiedinthescrewinformation
tableforeachstep.
•Ensurethattorquescrewdriversarecalibratedcorrectlyfollowingcountryspecifications.
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