Agilent Technologies 89410A Service Manual page 48

Troubleshooting the Analyzer
To troubleshoot display failures
5
Check the digital output signals to the LCD display.
a
Using a logic probe verify that TTL logic pulses are present at the
following locations:
Signal Line
B0
B1
B2
B3
B4
B5
G0
G1
G2
G3
G4
G5
R0
R1
R2
R3
R4
R5
DENA
VSYNC
HSYNC
CLK
b If any of the signals are incorrect, the A82 LCD Interface
assembly is probably faulty
c
Verify the back lights and inverter boards. When the display is in
the test position the back lights are visible from the side of the
display. Use this procedure if one or both are not lit.
a
Press Display, more display setup, color setup, brightness, 100%.
The brightness level controls the voltage applied to the back lights.
b
Check for 4.5 Vdc
+
c If this voltage is incorrect then the A47 assembly is probably
faulty.
d
Check for + 1.2 Vdc
1-30
Probe Location
R31
R19
R24
R23
R16
R22
R32
R20
R27
R26
R17
R25
R33
R21
R30
R29
R18
R28
R36
R38
R37
R44
0.2 V at A82 TP2 using a voltmeter.
±
± 0.2 V at A82 TP8 using a voltmeter.