The filament supply is an AC stabilized voltage supply, powering the klystron filament through a filament intermediate transformer, the pulse transformer located in the fuel tank, and the filament transformer. On 18 July 2011, at the Tongliao weather radar station, Inner Mongolia, the CINRAD/CB radar transmitter recurred filament power supply failure: there was no high voltage, leading to radar shutdown. By careful troubleshooting, the radar failure was removed successfully. The failure reasons are analyzed in detail, and the results are suggestive for the maintenance staff at radar stations