From the analysis on phenomenon, fault should be out in the chrominance signal processing circuit. After failure occurs 38 feet voltage measurement, found completely normal, using oscilloscope waveform observed 42 feet, also normal. Observation subcarrier (oscilloscope probe hook in the middle of the X630 and C638) is normal. Considering the oscilloscope is unable to accurately read frequency, therefore still will X630 and C638 change new, but failed to troubleshoot, illustrate that subcarrier oscillation circuit is normal. To check 30 feet outside the APC filter circuit, after the replacement of C630, troubleshooting.4caservice manual download site