Source: Beijing TCL TV Repair Center, http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3701157.
**Problem Description:**
In a TCL TV, the image is missing blue color, but the blue screen displays normally.
**Analysis and Repair:**
The focus of the inspection should be on the blue video amplifier circuit. After turning on the TV, measure the collector voltages of the three guns (Q505, Q507, Q509) on the tube base board. It was found that the voltage of the blue gun is abnormally high, indicating it is in a cut-off state. Further measurement revealed that the base voltage of Q509 is very low, which means Q509 is not functioning.
Next, the voltage at pin 43 (blue signal output end) of IC201 (TA8759BN) in the blue primary color circuit was measured and found to be abnormal, suggesting a fault in IC201 and its peripheral circuitry. Upon further examination, it was discovered that the voltage at pin 64 (B-Y output end) of IC201 deviates significantly from the normal value. Checking the peripheral components of IC201, including R201, R202, C201, and C202, revealed that resistor R202 on the blue primary color board is open-circuited.
**Solution:**
Replace the faulty resistor R202. After replacement, the problem was resolved.