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pFdservice manual download site
Check the machine AFT circuit see the appended drawings. Which IC102 (mu PD4066BC) as the AFT on/off control, CPU (MN152810TTC3) {8} feet turn on/off control for the AFT end, 21} {feet for AFT voltage input, putting IC101 (M52034SP) {2} feet for AFT voltage output. TV set in the condition of normal watch, AFT function is enabled, the CPU {8} feet AFT output low level, IC102 {5}, {6} feet for low potential, its {8}, {9} and {3}, {4} feet internal switch are disconnected, {12} feet for high potential, {10}, {11} feet inside the switch. Output voltage of AFT IC101 {2} feet by IC102 {11} and {10} feet to high-frequency head AFT terminals, for high frequency head AFT control. The TV set is in a state of channel, the CPU output AFT {8} feet high level, the IC102 {5}, {6} feet for high potential, its {8}, {9} feet inside the switch, high-frequency head AFT terminal provided by R1155, R155 fixed bias voltage. At the same time, {3}, {4} the foot switch is turned on, {3}, {12} feet for the low potential, {10}, {11} inside the foot switch, cut off the high frequency head AFT end and IC101 {2} the connection between the feet. Output voltage of AFT IC101 {2} feet also after Q151 and its peripheral circuit level transform to CPU {and} feet, the voltage for the use of CPU accurate lock table. pFdservice manual download site
The fault machine in the transformation channel instantaneous sound and image is normal, that the CPU data is correct of the deposit, at the same time also means putting AFT of the output voltage is accurate. Why the problem in the high frequency voltage of the head AFT by moments after conversion channel decreased from 4.4 V to 0.8 V. Measuring IC102 {9}, {10} foot voltage of 0.8 V, and {11} feet for 10 V, visible, IC102 {10}, {11} the foot switch is not connected. Measured again {12} feet voltage of 5.6 V, belong to high voltage, check the power supply end voltage of 12 V is normal, 14} {foot as a result, judge IC102 {10}, {11}, {12} foot damaged internal circuit. After replace TC4066 IC102, troubleshooting.
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