Analyze maintenance: open the casing inspection, found that the insurance tube F801 was burn out. Check separately according to the conventional way of thinking, degaussing resistance D840 C856, rectifier, filter capacitance, rectifier bridge pile D807, voltage doubling conversion circuit, the main power switch tube Q801, remote control on the power switch tube Q881 breakdown phenomenon. In a new insurance tube, open the power switch, measuring power plug on both ends of the resistance of 260 Ω, no short circuit phenomenon. Plugged in boot, insurance tube F801 burned again. 2A5service manual download site
 2A5service manual download site
 2A5service manual download site
Inspection by subsection method gradually narrowing the scope of the fault. First disconnect D86 plug, don't burn F801 boot. Fault area may be on the TNP107600AB switching power supply unit board. Further check panel all components, no detected fault components. Reoccupy fractionation method further narrowing the scope of failure, with D86 plug, disconnect the main power switch tube Q801 base of R813 starting resistance and the collector, to boot, burn F801 also. Failure may form in remote control 5 v power supply circuit. Further examination 5 v circuit formation, did not find fault components. Return to connect the main power switch tube base of R813 starting resistance and the collector, and disconnect the remote control 5 v power supply circuit, boot, also burn F801 insurance tube. Fault is not in the switching power supply, circuit board circuit TNP107600AB before. Don't burn F801 before Syria disconnect D86 plug after may be a chance phenomenon. Disconnect D86 plug boot test again, F801 was destroyed. The analysis is correct. 2A5service manual download site
 2A5service manual download site
Grid fault range that filtering, TNP107622AA degaussing circuit boards and doubler rectifier board TNP107599AB, further narrowing the scope of the fault were used to check and find out fault area on the grid filtering, TNP107622AA degaussing circuit boards. Respectively check the grid filter coil L813 L814, L815, L806, L816 and related capacitance C861, C801, C827, C823, C892, C897, C898, D840 degaussing degaussing circuit resistance and R847 degaussing varistor on resistance in parallel with grid parallel R892 (3.3 M Ω 2 w), still did not find the fault components. Question the soft breakdown phenomenon, degaussing resistance D840 degaussing resistance change with a new specification, or burning F801. Whether to change the quality has a problem? To change a new degaussing resistance with specifications, still burning F801.

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