Sony MVC-FD71 Service Manual page 60

6. CONTRAST adjustment (PK-43 board)
This adjustment sets correctly the VIDEO signal level that drives
the LCD. If disordered, LCD screen will not be sharp, or will white
blur or black blur.
Mode Playback
Alignment disk: Stair-step signal of 10
Signal
steps
CN802 9 pin (VG)
Measurement point
External trigger: CN802 7 pin (HSY)
Measuring equipment Oscilloscope
Adjustment page F
Adjustment address 35
A=2.90 ± 0.07 Vp-p (SHARP)
Specification value
A=2.18 ± 0.07 Vp-p (CASIO)
Adjustment procedure:
1) Set data: 01 to page: 0, address: 01.
2) Change the data on page: F, address: 35 so that the voltage (A)
between pedestal (0IRE) and 100IRE satisfies the specification
value.
3) Press the PAUSE button on the adjustment remote commander.
Processing after adjustment finished:
1) Set data: 00 to page: 0, address: 01.
2) Confirm that the specification value of the "BRIGHT
adjustment" is satisfied. If not, perform the "BRIGHT
adjustment".
A
Fig. 5-1-15
100 IRE
0 IRE
2H
7. V-COM level adjustment (PK-43 board)
This adjustment sets correctly the common electrode drive signal
level of the LCD panel.
Mode
Signal
Measurement point
Measuring equipment
Adjustment page
Adjustment address
Specification value
Note: The "CONTRAST adjustment" and "BRIGHT adjustment"
must be already finished.
Adjustment procedure:
1) Set data: 01 to page: 0, address: 01.
2) Change the data on page: F, address: 39 so that the COM signal
level (A) satisfies the specification value.
3) Press the PAUSE button on the adjustment remote commander.
Processing after adjustment finished:
1) Set data: 00 to page: 0, address: 01.
5-21
Playback
Alignment disk: Stair-step signal of
10 steps
CN802 8 pin (COM)
Oscilloscope
F
39
A=6.50 ± 0.05 Vp-p (SHARP)
A=5.10 ± 0.05 Vp-p (CASIO)
2H
Fig. 5-1-16
A