G Board; B Max Voltage Confirmation; B Ovp Confirmation - Sony KDP-51WS550 Service Manual

G BOARD

3-3. +B MAX VOLTAGE CONFIRMATION

The following adjustments should always be performed when replacing
IC6503 R6590.
1. Supply 130VAC to variable autotransformer.
2. Receive dot signal pattern and set the PICTURE and BRIGHTNESS
settings to their minimum.
3. Confirm the voltage of TP +B 135V is less than 137.0Vdc.
4. If step 3 is not satisfied, replace IC6503 and repeat steps 1-3.

3-4. +B OVP CONFIRMATION

1. Turn on set.
2. Set input conditions.
3. Turn off set.
4. Separate R6809 (D Board) from +135.
5. Apply external 145 ± 1V DC to open end of R6809.
6. Turn on set.
7. Measure voltage at Pin + of CN5007 (D Board). Voltage should be
less than 0.8V.
Input Conditions
Input Voltage: 120VAC
Input Signal: Dot pattern NTSC
Video Controls: PICTURE set to minimum
BRIGHTNESS set to minimum
— 39 —
KDP-51WS550/57WS550/65WS550