N5171B, N5181B; N5166B, N5172B, N5182B - Keysight Technologies X Series Service Manual

Troubleshooting
Unleveled Issues
Since the hardware within the ALC loop differs by instrument model, follow the
troubleshooting procedure below for the instrument being serviced.

N5171B, N5181B

These instruments do not have any other assembly inside the ALC loop other
than the A3 RF assembly. So, the ALC detectors, the ALC control, and the ALC
modulators are all located on the A3 RF assembly. Any unlevel condition
encountered is either the result of a hardware issue on the A3 RF assembly or
of an adjustment error. To isolate the cause of the unlevel perform the
following steps:
1. Verify the power supply voltages by seeing the
2. Verify that the instrument is using the factory calibration data by restoring
3. Run the following adjustments:
4. If the adjustments fail or the unlevel condition persists, replace the A3 RF

N5166B, N5172B, N5182B

Since the main difference between these models and the others is the addition
of the A2 Vector BBG assembly, first determine if the A2 Vector BBG assembly
is the cause of the unlevel. Use the following procedure to do so:
1. If the instrument has option 012 verify that the rear panel LO jumper cable
2. Determine if the unlevel error only occurs when the I/Q modulator is
3. Verify the power supply voltages by seeing the
4. Verify that the instrument is using the factory calibration data by restoring
Keysight CXG, EXG, and MXG X-Series Signal Generators Service Guide
Quick-Check" section in
the data. See "Calibration Data Restore"
Information and Calibration
ALC Linearity Calibration
Absolute Power Calibration
ALC Calibration
assembly.
(W16) is connected between the LO OUT and LO IN ports.
turned on.
— If the unlevel error occurs only when the I/Q modulator is turned On
go to the "I/Q Modulator Unlevel"
troubleshooting this error.
Quick-Check" section in
the data. See "Calibration Data Restore"
Information and Calibration
Chapter 8, "Power Supply".
in Chapter 3, "Instrument
Data".
section to continue
Chapter 8, "Power Supply".
in Chapter 3, "Instrument
Data".
"Power Supply Status
"Power Supply Status
135