Ceyear 4051 Series, User Manual

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7 Fault Diagnosis and Repair
7.1 Operating principle
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7 Fault Diagnosis and Repair
This chapter will introduce how to find out problems and receive the after-sale service. Indicate error
messages of the signal/spectrum analyzer. In case of any problem in operation of the 4051 series
signal/spectrum analyzer you purchased or when you need to purchase relevant components or accessories,
please contact us as we provide complete after-sales services.
In general, the trouble is caused by failure of hardware/software or users' misuse. Please contact us
immediately in case of any trouble. For the signal/spectrum analyzer within the warranty period, we will
implement free repair according to the commitments in the warranty; otherwise, we will charge the costs.
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Operating principle
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Fault diagnosis and troubleshooting
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Error information
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Repair
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7.1 Operating principle
To help users better understand functions of the 4051 series signal/spectrum analyzer and solve problems
occurred during operation, basic operating principles and hardware schematic diagram of the signal/spectrum
analyzer will be introduced in this section.
7.1.1 Operating principles and hardware functional block diagram
Controlled by a microprocessor and operated based on Windows 7 operating system, the instrument is a triple-
conversion superheterodyne sweep type signal/spectrum analyzer. It consists of microwave receiver module,
RF processor module, synthetic LO module, data collection & processing module, DSP processing module,
control display module and power module. The functional block diagram of the instrument is as shown in Fig.
7.1.
Fig. 7.1 Functional block diagram of 4051 series signal/spectrum analyzer
The block diagram of frequency conversion of the microwave and millimeter wave circuit is as shown in Fig.
7.2.
The 3HzGHz signal of zero wave band enters the low-band frequency converter module from the input
terminal via the 14 dB switch DC block programmable step attenuator, the 58 dB programmable step
attenuator and the duplexer, mixes with the signal from the first LO (YIG oscillator) to obtain 5.225 GHz IF
signal. Such IF signal goes to the second frequency converter in the low-band frequency converter module via
the 5.225 GHz band-pass filter and mixes with the 4.8 GHz beat frequency to get 425 MHz second IF signal.
When the frequency is less than 1.1 GHz and the frequency span is less than 5 MHz, the instrument
automatically enters phase noise optimization mode where the input signal mixes with the two divided-
frequency signal (2.825 ~ 4.525 GHz) from the first LO (YIG oscillator) to obtain 2.825 GHz IF signal. Such
IF signal goes to the second frequency converter in the low-band frequency converter module via the 5.225