Agilent Technologies M1205A V24, Руководство по обслуживанию, Страница: 105 / 358

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Attach a voltmeter to two test points where shown.
Unplug Flat Panel cable.
Turn contrast knob. The voltage reading should indicate a range of between -12 and -21
volts DC (approximate) as you adjust the potentiometer. If you cannot control the voltage
with the contrast knob, replace the Flat Panel Adapter Board or contrast control assem-
bly.
If you can control the voltage with the contrast control, replace the Flat Panel assembly.
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___If the
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Flat Panel backlight fails to light, the source of the problem may be the cable
connecting the System Board to the CDCI Board or in the later version to the Display Driver
Board, cable connecting the CDCI Board to the Flat Panel Adapter Board, cable connecting
the Flat Panel Adapter Board to the Flat Panel, Converter cable, Converter Board, the Flat
Panel assembly, or the backlight.
__If the color Flat Panel screen appears totally black, try viewing it obliquely from above a
perpendicular aspect: the screen will appear dark blue if the backlight is on.
__If the color Flat Panel backlight is working, but the screen is blank, then the power supply
(+5V), System Board, DSPC (Display Controller) Board or the Display Driver Board of the
new version, the Flat Panel assembly or possibly cables could be defective.
For the old color display, the backlight inverter circuitry is internal to the Color Flat Panel
display assembly.
For the newer color displays, the Converter Board is located on the Flat Panel display frame.
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Use this section if any of the power status LEDs on the power supply assembly (visible
through the LEFT air vent) that should be illuminated per the source power are extinguished,
or if a blown fuse is suspected as the source of the problem.
Turn off power.
TP4 Flat Panel GND
TP5 VLCD
Monochrome Flat Panel Adapter Board
Test Points
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