**Samsung TV, a horizontal bright line appears on the raster. Sound is normal.**
**Analysis and Repair:** Since the sound is normal, the focus should be on checking the field scanning circuit. This circuit uses a dual-standard single-chip field scanning integrated block IC301 (LA7838). The negative polarity field trigger pulse output from pin 64 of TA8880AN is sent to pin 2 of LA7838 to trigger the monostable circuit. Pin 1 of IC301 is the power supply circuit for the pre-stage (field driver stage), pin 8 is the power supply circuit for the post-stage (field output stage), pin 3 is the RC time constant circuit for the monostable trigger, pin 4 is the amplitude adjustment circuit for the sawtooth wave formation, and pin 7 is the AC/DC feedback input terminal used to correct field scan linearity distortion caused by screen curvature. The field scanning current is output from pin 12, passing through L301, the field deflection coil, coupling capacitor C306, and resistor R305 before being grounded. After the above analysis, the voltage at pin 8 of IC301 was measured as 27V (normal), and the voltage at pin 1 as 9V (normal). Then, the voltages at other pins were measured, and it was found that the voltage at pin 3 was only 1.2V, while it should normally be 4.6V. Checking the peripheral components related to pin 3 revealed that capacitor C331 was malfunctioning.
**Data Source:** Beijing Samsung TV Repair http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3685266.
**Solution:** After replacing C331, the fault was eliminated.