Contrast And Brightness Voltage Setting Adjustment - Casio QV-4000 Service Manual And Parts List

4-2. Contrast and Brightness voltage setting adjustment

1. Preparation
• AC adaptor or voltage regulator
• Digital oscilloscope
2. Adjustment procedure
(1) Start up Test mode Menu3.
1. Turn POWER on while pressing DISP key and MENU button simultaneously
2. Quickly press keys in the order of TIMER key, TIMER key and MENU key.
(2) Select / Execute GRAY SCALE (10 step).
(3) Trigger VG waveform (CP344) by FRP (CP346) signal to adjust as noted below.
(4) Adjust CONTRAST VR (VR344) so that contrast terminal voltage(CP341) signal is 1.50 ± 0.05 Vp-p.
(5) Adjust BRIGHT VR (VR341) so that potential between signal's pedestal and 4 step is 2.16 ± 0.05 Vp-
p.
(6) Adjust CONTRAST VR (VR344) so that potential between signal's pedestal and 10 step is 2.00 ± 0.05
Vp-p.
(7) Remove the resistance set between the killer terminal (CP342) and the VCC5 (CP172).
3. Notes
• Consecutively, execute 5-5. TINT setting adjustment.
• Make sure that waveforms are not distorted.
4. Connection diagram
Vcc1-1
Power
Supply
QV-4000
MAIN-PCB
Killer terminal
(CP-102)
(CP342)
VG(CP344)
— 25 —
VCC2
22KΩ
Bright adjustment
Digital oscilloscope