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6. RA-3/3A Video Process Troubleshooting: T & S Models
view video where it is inserted into the Y/C Jungle into a separate port. By engaging this function, you can get a
good idea of where the video loss is occurring. When the twin boxes appear, the main video source will be
displayed in the right box and the sub video in the left. What you will observe is one of three possible conditions:
Video in the right and left boxes, video only in the left box or no video in either box.
Video Appears in Both Boxes: This indicates that the main and sub video processing paths are functioning and
that IC206 is OK since the P&P video Y is switched into IC206 at the same point where normal video would enter.
YUV controller IC1407 is responsible for toggling between main and P&P luminance so this is the area to
troubleshoot. Either IC1407 is not switching in the main video or P&P controller IC1405 has IC1407 stuck in P&P
mode. Check pin 6 of IC1407 for 2.7VDC. If it is at 5VDC, troubleshoot the line to see what is pulling it up.
Video Appears in Left Box Only: There is a problem in the main video path. Since there are several sections, one
quick way to isolate the condition is to apply component signal to the video 4 or 5 input. This causes the Y signal
to bypass the A/D converter (IC203), 3D comb filter (IC204) and main decoder IC1402. Y switch IC1410 will
route the component Y directly to IC1407. If component video appears, troubleshoot the circuits listed above
that were bypassed. If component video does not appear, suspect AV switch IC1702 or YUV controller IC1407.
No Video in Either Box or No Boxes: The presence of boxes is a good indicator that P&P IC1405 is able to
generate the necessary switching and box borders, and that the IC1407 is able to send them to the Y/C Jungle.
Since the original problem was no main video and the P&P controller gets both main and sub video, the only area
left that is common to both video paths is the A/V switch IC1702. It has failed or cannot function because of
missing voltages, or the microprocessor IC002 cannot communicate with it.
If no P&P boxes are present, IC1407 may be incapable of passing any video or IC206 is suspect. Isolate the
problem by checking for video at pins 1, 2 and 3 of IC206.
Video Level or Distortion Problems
Methods for isolating video level or distortion is similar to the approaches used for the T and S models. Distortion
is more likely to appear in this design due to the A/D converter and 3D comb filter. Utilizing the P&P feature and
direct component inputs will assist in isolating the problem and are much in the same way as finding a no video
condition.
