As the picture seriously expanded and complicated with the "squeak" sound, is estimated to cause protection shutdown the machine existed after flow. So disconnect the line C pole, +B (113V) on the ground to pick a 100W light bulb, the bulb can light up, the +B output voltage is normal and no longer occurs. According to the above, the fault line output stage is indicated. The investigation and the output pipe, inverse range capacitance, the damper tube etc. are no exception, so doubt line output transformer or connected with the line output stage pressure stability (horizontal pincushion correction) circuit short-circuit fault occurs.

Will be line output transformer welding, with short circuit tester test, proved not damaged, obviously, the fault in the high voltage and stable (horizontal) circuit. The machine of the high voltage stabilizing circuit as shown in the following illustration. Belonging to the line deflection current control type, its working principle is: when the image brightness is high, the figure in a voltage decline, 0707 B pole voltage decline, conduction increased, Q702 B pole voltage rise - > conduction weakened, Q70l B current decreases, c current decreases, conduction, namely 0701 C, e very equivalent resistance line deflection coil impedance increases increases, line deflection current decrease, avoid the amplitude increase, equivalent to reduce the output tube load, remained the high-pressure constant weakened. When the inductance coil of the output stage of the line is cut off, the test machine is no longer protected, and the grating appears. Obviously, the fault is indeed in the high voltage stability circuit. Note that only the output stage of the fault can cause the output current level is too large, so directly to the output tube Q701 (2SD872) for inspection, found that the breakdown. After the replacement, the fault disappears.