东芝 C-1831Z 型彩色电视机的亮度通道是由6.5MHz 陷波器、第一视放、第二视放、箝位电路、第三视放、第四视放(勾边电路)、亮度延迟和第五视放等电路组成,方框图如图1所示。它的主要功能是在输入的全电视信号中滤除6.5MHz 的伴音信号,然后进行放大;放大后的信号经箝位电路恢复失去的图象直流分量;再经勾边电路,使图象清晰;而后经亮度延迟,使亮度信号在时间上与色度信号一致;最后经第五视放加至矩阵电路。除此之外,本电路还包含对比度控制、亮度控制,自动亮度限制(ABL)以及场,行消隐等功能,电原理图如图2所示。(一)6.5MHz 陷波器和对比度控制电路本电路的第一和第二视放级是色度和亮度信号的公共通道,全电视信号经 Z_(201)和 L_(201)组成的6.5MHz陷波器后,滤除其中的伴音中频信号,以防止伴音对图 Toshiba C-1831Z-type color TV brightness channel is a 6.5MHz notch filter, the first video, the second video, the clamp circuit, the third video, the fourth video (hook circuit), the brightness delay And the fifth as the circuit and other components, the block diagram shown in Figure 1. Its main function is to filter out the 6.5MHz audio signal in the input full-TV signal and then amplify it; the amplified signal is recovered by the clamping circuit to restore the DC component of the lost image; and then by the hook-and-loop circuit to make the image clear ; And then by the brightness of the delay, so that the brightness of the signal in time with the chroma signal; Finally, by the fifth as the video added to the matrix circuit. In addition, the circuit also includes contrast control, brightness control, automatic brightness limit (ABL) and field, line blanking and other functions, the electrical schematic shown in Figure 2. (A) 6.5MHz notch filter and contrast control circuit The first and second video playback circuit of this circuit is a common channel of chrominance and luminance signals, the full TV signal by Z 201 and L 201 (201) 6.5MHz After the trap, filter out the audio intermediate frequency signal to prevent the sound on the map