Determining If The Optical Unit Is Ok - Sony KZ-32TS1U Training Manual

Chapter 21 - Determining if the Optical Unit is OK
The optical unit can fail, producing:
•
TV Shut down by loading down the power supply.
•
White or black screen.
•
Missing a color.
If the TV shuts down (probably without a Standby LED fault indication), the optical unit can be unplugged and the
TV powered up to see if the TV remains ON. Normally, when all four cables to the optical unit are removed, the
TV will display a no picture bright white screen with sound (OK). If only the RGB signal input cable at CN5005
were unplugged, the screen would be ¼ bright, sound OK.
CN5002
Power In
Orange
FIGURE 21-1 - OPTICAL UNIT CONNECTORS (TOP VIEW)
White or Dark Screen - In a conventional TV, a loss of signal results in a white screen. This is also true in this
LCD projection TV. However, if the screen is dark with normal sound, the LCD optical unit or the previous circuit
board may be bad. On the other hand, a dark screen without sound indicates video and audio muting by the
Main Micro. This is because of either: a communications problem with another IC, a fan defect, a lamp circuit
defect, or an audio output failure which may also cause TV shutdown but not a video failure.
If the screen is white, there may be no input to the optical unit. Check for loss of input voltage at CN5002 and
RGB input signal at CN5005. If the input voltages and signals are present, the optical unit is suspect.
Table 21-1 - Optical Unit Input Voltages and Signal Levels (color bar input)
Input Voltage
(from G board)
CN5002/pin 1
(white)
CN5002/pin 3,4
(orange)
CN5002/pin 7,8
(orange)
CN5002/pin 11
(orange)
If the screen is black, the optical unit or BB board may be bad.
Determine which one by unplugging the CN5002 power connector to the optical unit. If the screen becomes
white, the BB board is bad. A white screen is normal if the optical unit loses power (it passes all the backlight).
If the screen remains black, the optical unit is bad.
If the screen is missing a color, the RGB signals entering the optical unit (CN5005) have to be verified before
accusing the optical unit of the failure. The signal levels are given in Table 21-1.
Level
- 7Vdc CN5005/pin 1
(Blue signal)
5Vdc CN5005/pin 3
(Green signal)
3.3Vdc CN5005/pin 5
(Red signal)
15Vdc CN5005/pin 7
(Vert sync)
CN5005/pin 9
(Horiz sync)
45
CN5005 RGB, sync in (gray)
CN5001 DATA, blanking (red)
CN5004 S Data (white)
Input Signal
(from BB board)
2.5Vp-p
2.0Vp-p
2.4Vp-p
5Vp-p
5Vp-p
5. Adjustments
Level