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28. Grand Wega Video Process
Table 28-2 – Optical Unit Input Voltages and Signal Levels (color bar input)
Input Voltage
(from G board)
Level
Input Signal
(from BB board)
Level
CN5002/pin 1
(white)
- 7Vdc
CN5005/pin 1
(Blue signal)
2.5Vp-p
CN5002/pin 3,4
(orange)
5Vdc
CN5005/pin 3
(Green signal)
2.0Vp-p
CN5002/pin 7,8
(orange)
3.3Vdc
CN5005/pin 5
(Red signal)
2.4Vp-p
CN5002/pin 11
(orange)
15Vdc
CN5005/pin 7
(Vert sync)
5Vp-p
CN5005/pin 9
(Horiz sync)
5Vp-p
Black Screen
If the screen is black, the optical unit or BB board may be bad. First, see if the Menu feature functions. Press the
Menu button on the remote control. If the screen displays the OSD menu, the optical unit assembly is working
and the BB board is suspect.
If there is still no display, remove the input power to the optical unit by unplugging the power connector CN5002
(see Figure 28-2). If the screen becomes white, the BB board is bad. A white screen is normal if the optical unit
loses power (the optical unit passes all the backlight). If the screen remains black, the optical unit is bad.
CN5002
Power In
(orange)
CN5005 RGB, sync in (gray)
FIGURE 28-2 - OPTICAL UNIT CONNECTORS (TOP VIEW)
CN5001 DATA, blanking (red)
CN5004 S Data (white)
Video Screen Distortion
Distortion, defects or interference can enter the video chain at any of its five boards used in the video processing
chain. You can use some features to help determine where the video problem is. The features most helpful in
isolation are: the On Screen Display (OSD) menu, the MILD picture mode, activity in Video 5/6 inputs and the
Twin View Mode.
On Screen Display to Check the Optical Unit
You can use the On Screen Display Menu to check the circuitry after the BB board. If the screen displays no
(black or white) picture or a distorted picture, press the Menu button on the remote control. If the screen displays
the OSD menu undistorted, the optical unit assembly is working (along with the OSD circuit in the later stages of
the BB board where the OSD circuit is). See Figure 14-1. If the OSD Menu is present, this also means the BB
and BC boards are the primary suspects causing the video distortion.
Video Problem that does not appear in the MILD Picture Mode
When watching an NTSC program from the tuner or video 1-4 inputs, this video signal passes through the DRC
and MID circuits on the BB board. By selecting the MILD picture setting, this video signal is diverted around the
DRC stage.
Therefore, if the NTSC video problem does not appear when selecting the MILD mode, the problem is on the BB
board in the DRC circuit.
