The aircraft initially appeared three non- users are looking for someone to repair the line pipe inspection results Q551 (2SD1439) breakdown, can not find the other bad elements , and replace the use of a new line pipe 2SD1555 failure took place about two hours , and then check the situation remains supra , is one such replacement . After receiving the check repair the boot lid and wrap the tube does breakdown . Based on past experience in the maintenance , first check the power supply voltage , disconnect the 113V power supply circuit R556, C808 at both ends and then a 60W/220V bulbs , power supply output voltage is 113V electricity measured normal to observe a long time and is very stable , indicating that the fault is not in power . Check the line circuit without open welding , Weld , circuit boards and components without breaking bad phenomenon , check the line output transformer , the normal deflection coil , measuring flyback capacitor C551 ~ C554 without open and capacity were normal. Because they found no obvious cause of the malfunction , but for insurance purposes or substitution of authentic line output transformer and flyback capacitor , put the line pipe test machine observation, just machines Figure sound normal, but does not appear long swath irregular contractions or shrink and twist to the right and sometimes evasive few normal again , sometimes the boot does not start, the machine has a squeak when not start measuring 113V voltage is normal , IC501 (AN5435) ⑤ pin voltage rises to 0.9V, described the protection circuit , check IC501 and perimeter protection circuit elements without exception . Under normal circumstances, the test machine turned on for about an hour and observed three non- emergency , check line pipe breakdown again. So what causes repeated firing line output tube it? After careful review found that the Bank of China to promote the pipe line drive circuit Q501 (2SC1573) at the dusty , dirt between the pin -like gross profit was analyzed there is leakage of the suspects , the trial ethanol to completely remove dust , back into the output pipe , try Symptom eliminate the aforementioned machine really work as usual, no recurrence was observed using several months .

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