HP 54616B User And Service Manual page 127

Disconnect the ribbon cable from the display board, then check the
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following signals on the system board.
Table 4-15 Signals from U609 (HP 54615B and HP 54616B)
Signal
U817 Pin 7
U817 Pin 24
J803 Pin 13
Signals from U609 (HP 54616C)
Signal
U827 Pin 7
U625 Pin 35
U625 Pin 20
If the signals are good, replace the display assembly. If not, replace the
system board.
Disconnect the ribbon cable from the display board.
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Go to "To check the Low Voltage Power Supply," on page 4-40.
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If the voltages are within the test limits, replace the display assembly. If not,
do the steps below.
a
b
c
d
Name Frequency
DE 19.72 kHz
Hsync 19.72 kHz
Vsync 60.00 Hz
Name Frequency
DE 16.67 kHz
Hsync 16.67 kHz
Vsync 50.05 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).
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 µs
5.0 Vp-p
3.0 µs
5.0 Vp-p
253.5 µs
5.0 Vp-p
Pulse width Voltage
48.0 µs
5.0 Vp-p
2.90 µs
5.0 Vp-p
360.0 µs
5.0 Vp-p
Service
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