The two most common faults microcomputer microwave and membrane switch or FPC printed circuit related to ( 1 ) the majority of the keyboard key switch failure. FPC film switch or leakage is a common cause of the presence of this fault , the microwave leakage is due to moisture and long board computer or erosion caused by water , but also from the appearance of the circuit board is sometimes difficult to determine whether the leakage , it is necessary to direct the use of anhydrous alcohol wipe or clean membrane switch , FPC and PC board , the Mets have an effect . This failure may also be printed by the FPC line break caused several occur simultaneously , but this is basically caused by improper maintenance , it is more rare. Just checking to see with the naked eye or a multimeter to measure , will soon be able to check the fault lies, re-weld break to troubleshooting . ( 2 ) the individual keyboard key switch failure. And the failure of the switch corresponding FPC membrane switch line break or poor contact is the main cause of this failure. Will be able to rule out the failure can be found in the corresponding membrane switch and circuit switching , reference to the above method of treatment failure.7K4service manual download site
  Care must be taken , and maintenance of computer keyboard circuit board and other components , should adopt a small sharp tip 20 ~ 25W soldering iron , and iron enclosure should be grounded, if there is no post- conditions need to be heated electric iron and then unplug to use.7K4service manual download site