电脑键盘维修集锦（Computer keyboard maintenance highlights）.docVIP

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电脑键盘维修集锦（Computer keyboard maintenance highlights）.doc

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电脑键盘维修集锦（Computer keyboard maintenance highlights） Computer keyboard maintenance highlights Wang Jiyu, Tian Guohua 1992-12-25 Fault phenomenon 1 in the microcomputer work, type a key, the screen shows more than one character, each time the characters displayed are different, so that it can not work properly. Fault analysis of CH keyboard, all the key (such as the space key, the Enter key etc.) key is provided with a bow shaped wire to make the cap and the key seat is connected, because these key force will shock struck, the connecting wire off and fell on the printed circuit board, destroyed the correct connection caused by printed circuit. Troubleshooting off cap, the steel wire can be connected. Malfunction 2. When a key is typed, no characters are displayed on the screen. Fault analysis of the key may be due to the use of high frequency or by keystroke force is too large, the connection between the base and the key to produce weld circuit board; the circuit is broken by the key. Troubleshooting: remove the connecting screws on the back cover of the keyboard, remove the front cover of the keyboard, remove the keyboard body, and re weld the key on the back. Two 、 PC/XT keyboard trouble and maintenance After the boot, the keyboard does not respond to all keys, the keyboard is locked. Analysis and elimination method can estimate the fault phenomenon from the failure of printed circuit board in the keyboard failure, because the keyboard itself contains a micro switch matrix, a 8 bit microcontroller 8048, with 2KROM and its associated circuit to complete the control operation. The keyboard circuit shows that the emergence of such a failure in addition to the 8048, and also on the system board 74LS322 (8 bit serial / parallel input register (8255) and a programmable peripheral device interface); here, the exchange method and exclusion combined to troubleshooting, respectively to 8048 and 74LS322 and the 8255 test, which replace the bad chip, failure can be ruled out. Th