ROHDE SCHWARZ - SFU - Error

[OliverWirthg]

Hi everyone!

My R&S SFU reports an error: "Synchronization error on reference PLL - please check ext. reference connection". In the HW settings it is set to: Reference -> Internal (10 MHz). I measured at the "Ref Freq Out" connector, it seems that the reference signal is present. I switched the HW setup to an external signal and connected the signal from the stable generator to the "Ref Freq In" connector. The error was still present. Anyone have any idea what's wrong?

Is it possible to get service documentation for these instruments or is it an R&S secret?


Thank you all!

[OliverWirthg]

In addition, would anyone be able to advise how the diagnostic data can be verified according to Fig.? For some of them the voltage values are listed but not for most of them. Is there any document for verification?