Diagnostic information 2-151
7002-xxx
LCD touchscreen backlight—models X644e/X646e
Unable to change LCD touchscreen backlight.
FRU Action
1 Inverter card 8-pin cable 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 Check the voltages on CN1-1 and CN1-2. They should measure
approximately +12 V dc.
If incorrect, replace the operator panel card assembly. If correct, go to
step 4.
4
Inverter card assembly
Operator panel right cover
assembly
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.
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
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