JD785A false frequency signal repair

[HXG]

First of all, let me explain that my English is very bad.I use Google Translate, so some statements may not look good, please forgive me.In the JD785A spectrum mode, there is no input signal, but the spectrum display has a false signal. Originally wanted to disassemble the machine from the hardware solution, did not succeed, and later heard that people can solve these false signal problems through self-calibration. So ask how the JD785A spectrum mode self-calibration process works. Thank you.

[HXG]

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[HXG]

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