Repair of Agilent E4403B spectrum analyzer self-test error case

1. Instrument model: Agilent E4403B spectrum analyzer;

2. Fault description: Power-on self-test error

①LO UNLOCK

② Reference Frequency Error;

3. Whole machine inspection:

a) After testing, it was found that the first local oscillator signal of the A8 board was unstable, resulting in a LO UNLOCK error when the machine was turned on;

b) Further testing revealed that the frequency of the first local oscillator reference signal on the A8A1A2 module was unstable, resulting in unstable output of the first local oscillator YTO;

c) Finally, it was determined that the fault was that the 1/2 divider at the YTO input was damaged, resulting in unstable YTO input.