Brightness dark but does not meet the cause of tube power supply voltage. Such as anode high voltage is low, reduce brightness line of expanding at the same time; Accelerate the arc down, only lower the brightness; High grid-cathode bias, also only affect brightness. Dark brightness can also be caused by tube aging itself. N2fservice manual download site
 N2fservice manual download site
 N2fservice manual download site
Low voltage anode, and the feeding failure is different, can be caused by line output transformer; Accelerate arc down caused by line output transformer and accelerometers potentiometer, grid-cathode bias is high, the circuit by visual, brightness channel circuit, brightness control circuit, and the circuit of power supply circuit. N2fservice manual download site
First check the tube power supply is normal, at all levels to determine the fault is caused by tube power supply or their own reason. Also can use instant ask the method of grid and the cathode of short circuit, judge whether the tube aging. With 1 k Ω resistance will be either Yin, extremely instant grounding, if kinescope grating obviously shiny, that picture tube is normal, the problem in the power supply circuit, or failure is caused by tube aging. N2fservice manual download site
Use this method to prove fault in the power supply circuit. Cathode, accelerating voltage with a multimeter test, found the accelerating voltage is 200 v, adjustable speed potentiometer can heighten, had to walk even output transformer replacement. Replacement after brightness returned to normal.N2fservice manual download site