### Fault Phenomenon:
After powering on, a horizontal bright line appears on the screen raster.
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### Solution:
The fault was resolved by replacing R499.
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### Analysis and Maintenance:
The focus of inspection was on the field scanning circuit. After turning on the power, the voltage at each pin of the field output block IC301 (LA7838) was measured. It was found that, except for pins 1 and 2 which had normal voltages, the voltages at all other pins were abnormally low. Specifically, the voltage at pin 8 (field supply voltage) was only 0.2V, whereas it should have been 27V under normal conditions. This led to the suspicion of either a faulty field supply circuit or damage to the field output block.
When pin 8 of IC301 was desoldered and re-measured, the voltage of the 27V circuit was still found to be low, confirming the issue with the field supply circuit. In this TV model, the 27V voltage is generated from the pulse output of pin 6 of the horizontal output transformer T461. This pulse is rectified by R327 and D302, then filtered by C310 to form +27V voltage. The +27V voltage subsequently passes through R499 to provide the operating power supply to pin 8 of LA7838. Meanwhile, pin 1 receives a 12V voltage supplied by Q408 (AN7812F), which is stabilized and filtered through R231, L302, D315, and C311.
Based on the above analysis, the pulse voltage across resistor R327 was measured and found to be normal. Further measurement revealed that the negative terminal of D302 (EU2A) also showed a normal 27V voltage. Upon detailed inspection, it was discovered that resistor R499 (1/2W/1Ω) had become open-circuited.
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### Conclusion:
The root cause of the fault was identified as an open-circuit in resistor R499 within the field supply circuit. Replacing R499 resolved the issue.
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**Edited and organized by Beijing Samsung TV Repair Center.**
**Fault Summary: Poor field supply circuit in Samsung TV.**