Panasonic TC - 33 gf85r color grating is very dark, just picture the bright parts have a shadow, and blinking, swinging and wiredrawing phenomenon, switch transformer throbbed, rhythmic "cheep, cheep" -Service Manual Download|Circuit Download|Download Drawings|schematic download|route map download|free download user manual

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Panasonic TC - 33 gf85r color grating is very dark, just picture the bright parts have a shadow, and blinking, swinging and wiredrawing phenomenon, switch transformer throbbed, rhythmic "cheep, cheep"

Time：2014-06-05 08:33:04 Source：Network Author：Unknown Clicks：1254

According to the phenomenon of grating is very dark, the first detection of three way video output amplifier integrated block IC351 and peripheral circuit, as shown in the appended drawings. Measuring IC351 {1}, {2}, {3} foot video signal input voltage of 1.8 V, {5} feet (in-phase input), {6} feet (depending on the level of 221 V voltage power supply) voltage is normal, but the {7}, {8}, {9} foot (B, G, R output) voltage is 205 V or so  normal value is about 150 V), is due to {7}, {8}, {9} foot high voltage caused by the grating is dark. IC351 IC351 peripheral components without damage and test each foot of positive and reverse basic normal resistance value, estimated IC351 was not damaged, IC351 not in normal working state to enlarge, but by the state. Zjvservice manual download site
Zjvservice manual download site
Zjvservice manual download site
Along a, G, B R input signal examination, forward IC3401 {12}, {and}, {16} feet voltage 1.9 V, 2.0 V, 1.8 V, normal is 3.6 V, 3.5 V, 3.6 V. {6}, {3}, {1} foot voltage 1.7 V, 1.7 V, 1.6 V, normal is 3.5 V, 3.4 V, 3.5 V. {5} foot 12 v power supply voltage is normal. Check IC601 19} {, {36}, {} 50 and 59 {} the leg power supply voltage of the power input are around 7.6 V, and normal should be stabilized 9 V power supply. Along the circuit board to D board inspection, found that D three-terminal voltage regulator on boards IC805 {3} feet output voltage of 7.6 V, {1} feet and only 8 V input voltage, but C836 ends with normal voltage 12 V, R842 pressure drop is too large. Remove the R842 check, R842 has changed from 4.7 Ω value at about 14 Ω. With 4.7 Ω / 5 w resistance change after, fault disappear. Zjvservice manual download site
Because R842 resistance increases, the power supply voltage of the IC601 was normal 9 V is reduced to about 7.6 V, while IC601 combined video processing, pattern chroma decoding, synchronous separation, scanning line field oscillation, incentives, and other functions, thus cause the R, G, B video signal output decreases, cause the R, G, B amplifier circuit bias change, tube three high signal for cathode voltage, electron beam as basic, so the grating dimmed. Line at the same time oscillation is not normal, so see dark shadow flicker, swinging and have the phenomenon of wire drawing, line oscillation frequency caused by abnormal switch transformer "squeak" sound.

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