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Troubleshooting
Troubleshooting Assembly–Level Problems
Front Panel Display Assembly Troubleshooting
Overview
The Front Panel Display Assembly comprises the following:
• a 640 x 320 pixels liquid crystal display (LCD)
• a power switch/flat panel interface board, which contains the power on/off switch, standby LED,
and power–on LED
This board contains the circuitry to disable the power supply: in all models except the E8267C,
the ON_OFF control line is pulled to a TTL low; for the E8267C, the logic is reversed, and a TTL
high disables the power supply.
Another function of the power switch/flat panel interface board is to route the 8 data bits from
the A18 CPU to the A2 Display.
• a front panel board that contains the front panel hardkeys, softkeys, and RPG
• a dc to ac inverter, which turns the LCD on and off via control lines received from the CPU
The inverter also converts the 5.2 Vdc to approximately a 160 Vrms, 40 kHz signal to drive the
LCD.
Display Controls
Contrast There are two contrast hardkeys below the A2 Display. The left up arrow key
increases the contrast while the right down arrow key decreases the contrast.
Brightness The A2 Display brightness can be adjusted from 50 (high brightness) to 1 (low brightness) using
the RPG, arrow keys, or the numeric keypad.
Other display features located under the
Utility > Display softkey, include a screen saver and inverse video.
Display Tests The following two screen tests are available for the LCD:
• the Black Pixel Screen Test turns the display dark
• the White Pixel Screen Test turns the display bright
Softkey Location:
Utility > Display > More (1 of 2)
To exit the test, press any front panel key.
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