HP 54620A - Table 12 Display Signals

6
Disconnect the display cable, then check the following signals on the
system board, using an oscilloscope.
Table 12 Display Signals
HP 54620A Logic Analyzer
Signal Frequency Pulse width Voltage
U3 Pin 7 DE 19.72 kHz 38.0
µ
s2.6 Vp-p
U3 Pin 24 Hsync 19.72 kHz 3.0
µ
s5.0 Vp-p
U4 Pin 2 CTD_Sync 60.00 Hz 50 ns 5.0 Vp-p
HP 54620C Color Logic Analyzer
Signal Frequency Pulse width Voltage
U34 Pin 18 DE 16.67 kHz 48.0
µ
s5.0 Vp-p
U 39 Pin 21 Hsync 16.67 kHz 2.9
µ
s5.0 Vp-p
U 34 Pin 2 CTD_Sync 50.0 Hz 60.0 ns 5.0 Vp-p
If the signals are good, replace the display assembly. If not, replace the
system board.
7
Disconnect the LVPS ribbon cable from the display board.
8
Measure the power supply voltages again (steps 2-4).
If the voltages are within the test limits, replace the display assembly. If not,
do the steps below.
a
Disconnect the power cord.
b
Disconnect the ribbon cable from the power supply.
c
Connect the dummy load to the power supply connector.
d
Connect the power cord, then measure the power supply voltages
again, using a voltmeter (see new tolerances below).
+
5.1 V (4.95 V to
+
5.25 V)
+
15.75 V (
+
15 V to
+
16.5 V)
−
15.75 V (
−
15 V to
−
16.5 V)
If the voltages are now within the test limits, replace the system
board. If not, replace the power supply.
Testing, Adjusting, and Troubleshooting the Analyzer
To troubleshoot the logic analyzer
166