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Panasonic TC - part 21 l3r color TV channel audio noise big, individual channel even without sound and picture quality is poorer fault repair methods

Time£º2014-06-05 08:32:25  Source£ºNetwork  Author£ºUnknown  Clicks£º1353
  
zKAservice manual download site
After repair IC102 measuring voltage on foot for {5}, {6} feet 1 V, {3}, {4} foot 12 V, 5.7 V} {11 foot, {9}, {10} feet 5.7 V, 4.4 V {8} feet. Resolution of the original fault phenomenon is as follows: television channels in an instant, the switch IC1102 {8} feet, output level control IC102 {8}, {9} feet inside the switch, {10}, {11} internal switch feet, high-frequency voltage of the head AFT is determined by R155 center tap, measured at 4.4 V. Turn into normal watch, IC1102 {8} feet into a low level, control IC102 {8}, {9} feet inside the switch, and at this point should be connected to {10}, {11} feet, reliable due to internal circuit damage and cannot get through, IC101 {2} feet AFT voltage and therefore cannot reach high frequency head AFT end. High-frequency head AFT terminal external capacitance C111 on the voltage of 4.4 V after discharge dropped to 0.8 V, high-frequency head actually receive frequency offset, formed the fault phenomenon mentioned in the beginning of the article. IC101 {2} feet under the action of internal AFT circuit, the output voltage up to try to correct the frequency offset, but in vain, so a failure occurs IC102} {11 feet voltage higher than normal.zKAservice manual download site