| 摘要 |
PURPOSE:To detect the trouble of respective chrominance signals by using a single test signal by superimposing the test signal on the input part of the respective chrominance signals during a vertical blanking period and discriminat ing whether the test signal is outputted from respective units or not. CONSTITUTION:Video signals R, G, B respectively receive a signal processing in the units 4-7 and thereafter are outputted to a post stage. Herein, a trouble diagnosing test signal generated in a test signal generating means 14 is superimposed on the input part of the first step unit 4 during the vertical blanking period. According to the command from a microprocessor 12, multiplexers 8-11 disposed on the output parts of the respective units 4-7 are successively changed over and the respective channel output signals of the R, G, B of the units 4-7 are successively taken out one by one and inputted to a detecting circuit 13. According to whether the superimposed test signal can be detected or not, the signal of the color and the unit in which the trouble is generated is diagnosed.
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