Observe the machine boot about 20-30 minutes image and sound; AV condition. Normal figure. Enter the bus out AGC, AGC adjustment to the "20", fault disappear. Think you're done. V6Aservice manual download site
 V6Aservice manual download site
That evening the customer calling. According to image distortions. The door maintenance, found that the signal seems to be unstable, downs, sometimes no. Images and sound to disappear at the same time. On maintenance. The preliminary analysis for the circuit fault. Detection of high-frequency voltages, only AGC to low voltage (4.6 V), into the bus again to restore the original value of AGC, AGC voltage drop to 2 V, is still a bit low. Try ordinary high-frequency head substitution, fault, still judged to be putting board failure. But this machine more motherboard each function module, spacing is very small, can't repair. V6Aservice manual download site
 V6Aservice manual download site
 V6Aservice manual download site
Ask manufacturers, which put board prices as high as 400 yuan, decided to access into the plate. V6Aservice manual download site
 V6Aservice manual download site
This is a double panel into the plate. Component density is big, more for SMT components, including putting circuit for AN5179N, it provides the AGC voltage, audio signal output, and other functions. V6Aservice manual download site
 V6Aservice manual download site
Putting board power supply, the power converter for detecting voltage AN5179 each foot. When detected 19 feet, voltage of 3.7 V and is not very stable, normal should be 5 V. Disconnect C109, C157 19 feet external capacitance, voltage remains. With wire sub B1 (3) with AN5179 19 feet, voltage is normal, restore two capacitance, boot for several hours, failure is no longer present. V6Aservice manual download site
 V6Aservice manual download site
Between hindsight, double panel via various, I doubted to poor hole of voltage instability, AN5179 19 feet for the power supply side, the power supply is abnormal, must make put cannot work normally.V6Aservice manual download site