Front Panel Troubleshooting
Troubleshooting the front panel board involves checking for the presence of the correct bias voltages
on the board. Refer to the following table and figure.
Test Point Location Voltage Description
TP 1 BKL_VCC + 12 V If bias not present, troubleshoot the bias board or replace the front panel board.
TP 2 P1 pin 3 + 12 V If backlight voltage not present, replacethe front panel board. If voltage is present and
the display is not lit, replacethe display.
Common GNDB common
Bias Assembly Troubleshooting
Troubleshooting the bias circuits involves checking for the presence of the correct bias voltages on the
Bias/Processor Carrier board. Refer to the following table and figures.
Note that if the bias voltages at test points 2 - 4 in the following table are not present, it could be
caused by a defect in the power module, backplane, or front panel board that is pulling the bias
voltage low.
Test Point Location Voltage Description
TP 1 + VBS (red) + 48 V Output of bulk supply. If not present, replacethe bulk supply.
TP 2 P1 - 1 + 12 V If biases atTP 2, TP 3, or TP 4 are not present, disconnectthe backplane and front
panel cable assemblies and recheck. If biases are still not present, replacethe inter-
face/bias board.
TP 3 U48 - 2,3 + 5 V Same as above.
TP 4 P17 - 1 + 3.3 V Same as above.
TP 5 EGND (black) common
Keysight N6700C Operating and Service Guide 419
7 Service and Maintenance
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