Lexmark X642e Service Manual page 190

7002-xxx
LCD touchscreen display lights up, icons displayed, but it does not work when
touched.
FRU
1 LCD touchscreen display/
4-pin cable
2 LCD touchscreen display
Operator panel right cover
assembly
Inverter card
3
4 Inverter card assembly
Operator panel right cover
assembly
2-152
Service Manual
Action
Check the 4-pin display to operator panel card cable for correct
installation to J3 on the operator panel card.
Note: This cable is a short ribbon cable that can easily become
disconnected from J3 on the operator panel card.
If the cable is properly installed, go to step 2.
If the cable is connected properly to J3, replace the operator panel
right cover assembly. See
removal" on page 4-64. If this does not fix the problem, replace the
LCD touchscreen display assembly. See
removal—models X644e and X646e" on page
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 0 V dc
CN1—Pin 5 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
If this does not fix the problem, replace the LCD inverter card
assembly. See "LCD inverter card assembly removal" on
page 4-108.
"Operator panel right cover assembly
"LCD touchscreen
4-67.
4-64.