Sometimes when the color no and no fault parts of the same color, just no color fault components not completely damaged, when good or bad has yet to reach full state of decolorization. 8udservice manual download site
Closed to cause of color when sometimes no have. (1) the received signal is too weak, that removing color chroma decoding circuit circuit in the critical state of decolorization; (2) the TV antenna direction and matcher is not correct, cause the received signal is weak, the receiver is in the critical decolorization; (3) receiver tuned, color signal is weak, cause critical decolorization. 8udservice manual download site
The internal cause of color when sometimes no have: (1) the public channel frequency characteristic is poor, low gain, chroma signal amplitude is too small; (2) color sometimes no when synchronous gate; (3) color synchronous phase shifting circuit element poor contact: (4) the native subcarrier frequency unstable; (5) the APC filter element, make the APC voltage fluctuation; (G) decolorization voltage on the high side, to close the chrominance channels. 8udservice manual download site
(1) with 20 k Ω resistance would IC501 21 feet ground, people open the color channel, observed on the screen with color, but color is not stable. Possible reasons are: (1) the chroma signal amplitude is too weak. (2) color synchronous gate without to IC501 13 feet; (3) the machine subcarrier oscillation frequency deviation; (4) IC501 bad; (5) the APC circuit fault. 8udservice manual download site
(2) adjusting the subcarrier frequency components R514, has been in the best position. 8udservice manual download site
(3) the multimeter IC501 13 feet voltage measurement, no negative pressure, doubt is not to 13 feet line sync signal, check C524, R534, C525, R535, found R534 resistance value change of more than 70 k Ω. So send to 13 feet color synchronization gating signal is extremely weak, choose don't sync signal, so the chromaticity degree won't open. On the human and color are not synchronized. 8udservice manual download site
Replace 1 k Ω/o. after 25 w resistor color returned to normal.

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