Lexmark X644E Service Manual - Page 189
LCD touchscreen backlight-models X644e/X646e, Action, Submit
UPC - 734646093156
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7002-xxx LCD touchscreen backlight-models X644e/X646e Unable to change LCD touchscreen backlight. FRU 1 Inverter card 8-pin cable Action Check to make sure the cable is installed correctly to the inverter card and to the operator panel card. 2 Inverter card 8-pin cable Check continuity of the 8-pin inverter card cable. If correct, go to step 3. If incorrect, replace the cable. 3 Inverter card 4 Inverter card assembly Operator panel right cover assembly Check the voltages on CN1-1 and CN1-2. They should measure approximately +12 V dc. Inverter card Connector Cn1 (to operator panel card) Pin number Voltage CN1-Pin 1 +12 V dc CN1-Pin 2 +125 V dc CN1-Pin 3 0 V dc CN1-Pin 4 CN1-Pin 5 0 V dc 0 V dc (screen light Z) +4-5 V dc (screen dark) CN1-Pin 6 0-+5 V dc BRIGHTNESS ADJUST CN1-Pin 7 0 V dc CN1-Pin 8 0 V dc If incorrect, replace the operator panel card assembly. If correct, go to step 4. Enter the following Menus, Settings, General Settings, and Screen Brightness on the touchscreen display. • Enter 22 on the touchscreen display, and Submit the new setting. Measure the voltage at CN1-5. The voltage should measure approximately 0 to +1.5 V dc. • Enter 50 on the touchscreen display, and Submit. Measure the voltage at CN1-5. The voltage should measure approximately +2.7 V dc. • Enter 100 on the touchscreen display, and Submit. Measure the voltage at CN1-5. The voltage should measure approximately +5.0 V dc. If the voltages do not change when going from 22 to 100 on the display, replace the operator panel right cover assembly. See "Operator panel right cover assembly removal" on page 4-64. If this does not fix the problem, replace the LCD inverter card assembly. See "LCD inverter card assembly removal" on page 4-108. Diagnostic information 2-151