6 to 12 channel receiver aircraft normal, indicating that V-band high-level radioactive, mixers, local oscillator. In the work place are normal, 1 to 5 channels can not receive the focus of inspection frequency signal conversion circuit Square.grSservice manual download site
     (1) power measurement terminal switching voltage BS tuner, 1 to 5 channels of 30V, 6 to 12 channels is 0V, normal. Failure in the internal tuner.grSservice manual download site
     (2) Open the tuner cover change in the frequency transfer switch is set under paragraph 1 to 5 cases the measured channel switch DS1 ~ DS5 negative voltage. When measured to DS3, the negative voltage is 11.4V, explained R32, 4.7kΩ resistor open circuit, BS30V negative voltage is applied to less than DS3, DS3 conduction, the local oscillator coil L16 AC short. Therefore, thegrSservice manual download site
Vibration of 6 to 12 is still in the band, without intermediate frequency mixer output image signal, so there is no image.grSservice manual download site
     After replacing R32, 4.7kΩ resistor 1 ~ 5 channel receiver properly.grSservice manual download site