Service manual

ENWW Chapter 7 Troubleshooting 185

Troubleshooting the control-panel display

Try to fix common problems before replacing the control-panel display.

No display. If power-on is normal, but the control panel does not work, then try disconnecting

and then reconnecting the control panel connectors.

Poor display. If the control panel is working, but the display is illegible or shows poor contrast,

then check the contrast label (callout 1) on the back of the control panel.

Figure 105. Control panel contrast label

The contrast label contains a number that corresponds to an optimum display-brightness setting.

Change the brightness setting in the control-panel menus to the number shown on the label (see

page 65).

If the control panel display is so poor that it is impossible to use the control-panel menus, then

change the brightness after using a “bootup” key-sequence.

To use the “bootup” key-sequence

1 Turn the printer off.

2 Hold the B

ACK button down and turn on the printer. Continue to hold the BACK button until all

three LEDs are lit.

3 Press (S

ELECT) to enter the control panel contrast settings.

4 Press (S

ELECT) to advance to the LCD set.

5 Press (S

ELECT) to advance to the brightness settings.

6 Use the (U

P arrow) or (DOWN arrow) to scroll through the numbered settings.

7 Press (S

ELECT) to save the setting.