The Toshiba 2909XH TV is not working and is in a state of "three non-operations" (no picture, no sound, no power).
Analysis and Maintenance: Based on the fault symptoms, the power supply circuit was checked first. The measured regulated output voltage of 145V was very stable, indicating that the power supply circuit was functioning properly. Next, the horizontal scanning circuit was checked. The collector voltage of the horizontal output transistor was normal, but the base voltage was 0V, indicating the absence of a horizontal excitation signal. Therefore, the horizontal push stage and the horizontal oscillation circuit should be inspected closely. The voltage at pins 38~40 of TA8659N was measured to be normal, but there was significant fluctuation in the voltage at pin 37. The external component X401 connected to pin 37 was then checked. Its resistance was approximately 860kΩ, indicating that X401 was damaged.
Repair Method: After replacing X401, the fault was resolved.
Source: http://blog.sina.com.cn/dongzhids