HP 54600B User's And Service Manual page 132

Disconnect the display cable, then check the following signals on the
5
system board.
Table 4-18 Signals at U56
U16 Pin 7
U16 Pin 24
U9 Pin 2
If the signals are good, replace the display assembly. If not, replace the
system board.
Disconnect the Low Voltage Power Supply ribbon cable from the
6
display board.
Measure the power supply voltages again (steps 1-3).
7
If the voltages are within the test limits, replace the display assembly. If not,
do the steps below.
a
b
c
d
Signal Frequency
DE 19.72 kHz
Hsync 19.72 kHz
Vsync 60.00 Hz
Disconnect the power cord.
Disconnect the ribbon cable from the power supply.
Connect the dummy load to the power supply connector.
Connect the power cord, then measure the power supply voltages
again (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.
Troubleshooting the Oscilloscope
Pulse width Voltage
38.0 s 2.6 Vp-p
3.0 s 5.0 Vp-p
253.5 s 5.2 Vp-p
Service
4–43