Ceyear 4051 Series, User Manual

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7 Fault Diagnosis and Repair
7.2 Fault Diagnosis and Troubleshooting
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7.2.2.2 Instrument setup problems
When the signal/spectrum analyzer enters the test interface and successfully completed all starting calibrations,
the instrument will enter normal sweep test status and continuously refreshed traces can be seen on the screen.
However, if some parameters are not properly set, users may not be able to see traces or signals expected to be
shown. IF trace refreshing or signal display fails, please firstly check the following settings.
1) No trace refreshing or abnormal refreshing
In case of no trace refreshing or abnormal refreshing on the interface, please follow the step below:
a) Check if the instrument is set as auto trigger mode and continuous sweep mode. If the settings are correct,
but there is still no refreshing, proceed to the next step.
b) Open the marker and check if its reading changes. If the reading has changed, it may be caused by settings.
For example, the trace will be shown below the screen by setting the instrument as linear mode or setting
the reference level too high and thus is invisible. In this case, the instrument can be changed to log mode
or the reference level can be lowered before observing the trace. If the marker reading remains unchanged,
it indicates the error in sending back the trace. Please reboot the instrument. If the problem still remains,
please contact our customer service center according to relevant information in the Manual and provide
the error messages. We will help you solve the problem as quickly as possible.
2) No signal display
If no wave band has any signal display, please follow the steps: press
【
Input/Output
】
, [Input Port RF Align]
to check whether RF signal is selected. If not, check the RF signal. If there is still no signal display, it is
possible that the instrument hardware circuit fails. Please contact our customer service center according to
relevant information in the Manual and provide the error messages. We will help you solve the problem as
quickly as possible.
7.2.2.3 Abnormal signal frequency reading
If the signal is found jittering on the screen or the frequency reading is out of its error range during signal
measurement, firstly check whether the frequency of the input signal of the instrument is stable. If the signal is
stable, then check whether the instrument reference is correctly set and choose external or internal reference
based on different test scenarios by pressing
【
Input/Output
】
and [Frequency Reference External/Internal].
If the frequency reading is still not accurate by this time, it is possible that internal LO of the instrument loses
the lock. Please contact our customer service center according to relevant information in the Manual and
provide the error messages. We will help you solve the problem as quickly as possible.
LO lock loss is usually classified into the following types: loss of lock when frequency span ≤ 180 kHz; loss
of lock when 180 kHz < frequency span ≤ 2 MHz; loss of lock when 2 MHz < frequency span ≤ 20 MHz; loss
of lock when frequency span > 20 MHz; loss of lock under certain frequency points.
7.2.2.4 Abnormal signal amplitude reading
Abnormal amplitude includes abnormal low-band reading with normal high-band reading; abnormal high-
band reading with normal low-band reading; abnormal amplitude reading of signals of all wave bands; huge in
difference of amplitude reading between signals with different attenuator settings. If the signal amplitude
reading is inaccurate, run all IF calibrations in the instrument. If the reading remains inaccurate, it is possible
that the instrument internal circuit fails. In this case, follow the steps below:
a) Press 【 Input/Output 】 , [Input Port RF Align], [Cal Port], [500MHz] to turn on the 500 MHz calibration
signal of the instrument. Set the instrument center frequency as 500 MHz and frequency span as 1 MHz
and turn on Peak Search to measure the level of the 500 MHz calibration signal. If the instrument operates
normally, the amplitude of the calibration signal should fall in the range of -20 dBm ± 2 dB. If such
amplitude is not correct, it means that low-band (below 4 GHz) reading of the instrument is abnormal.
b) Press 【 Input/Output 】 , [Input Port RF Align], [Cal Port], [4.8GHz] to turn on the 4.8 GHz calibration
signal of the instrument. Set the instrument center frequency as 4.8GHz and frequency span as 1 MHz and
turn on Peak Search to measure the level of the 4.8GHz calibration signal. If the instrument operates