Panasonic TC-29GF95R TV the boot power lights are in turn orange, red, green light to red light has been flashing, fault repair method in three state |
| Time£º2014-07-18 08:23:23 Source£ºNetwork Author£ºUnknown Clicks£º1397 |
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iTtservice manual download site
iTtservice manual download site
The machine main switch power supply voltage control circuit is made in figure 6 IC802, D807 and IC801 6 feet internal circuit, etc. Known from the analysis of its voltage stability control principle, the causes of high voltage of the switch power supply output are: IC802 damage internal circuit, resistance R832, R814, R826 equivalent damage, open and D807 light activated triode C814 and D807 photodiode leakage or breakdown damage, etc. iTtservice manual download site
iTtservice manual download site
Remove the R832, R814, R826 measuring their value is normal, then remove the capacitance C814 measured its capacity is also normal, by now the rest of the fault components only photoelectric coupler IC802 D807 and error amplifier. According to the maintenance experience, general D807 damage probability is bigger. Remove the D807 test, the photodiode has leakage is damaged, replace D807 recover the original circuit of commissioning, troubleshooting. iTtservice manual download site
iTtservice manual download site
In addition the machine for the main switch power supply circuit has a variety of overvoltage protection control function, if when switching power supply voltage control circuit is out of control and cause an increase in output voltage, because T801 Yl - Y2 winding voltage synchronous rise, also after D802 rectifier, C811 filtering, cause voltage rise IC801 (5 feet, when the voltage one and more than 24 v. It could cause IC801 5 feet of over-voltage protection circuit and control, shut down automatically, switching power supply; At the same time, the voltage IC801 (4) feet will also rise, cause IC801 (4) feet in over-current protection circuit control. From this analysis can be seen, even disconnect voltage regulator circuits during maintenance, also won't because of the output voltage is too high and the breakdown of the load components. But for the sake of the whole machine base, in the implementation of the open loop voltage control loop, it is best to IC801 (2) the foot of the external flow sampling resistor R809, R810 any disconnect one, make the flow sampling resistor is composed of two 0.22 Ω parallel equivalent resistance (0.11 Ω) instead of a 0.22 Ω resistance, in order to improve the over-current protection of locus of control, in order to prevent the other overvoltage protection function fails, due to open circuit voltage loop output voltage increases, field effect caused by switch tube burned IC801 and breakdown due to flow load circuit components.
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