Casio QV-8000SX, Service Manual & Parts List

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5-8. Contrast and Brightness voltage setting adjustment
1. Preparation
• AC adaptor or voltage regulator
• Digital oscilloscope
2. Adjustment procedure
(1) Start up Test mode Menu1.
1. Turn POWER on while pressing DISP key and MENU button simultaneously
2. Quickly press keys in the order of FLASH key, FLASH key and MENU key.
(2) Select / Execute GRAY SCALE (10 step).
(3) Impress the killer terminal (CP308) with VCC2-1 (CP344) voltage through a 22k
Ω
resistance.
(4) Trigger VB waveform (CP322) by FRP (CP305) signal to adjust as noted below.
(5) Adjust CONTRAST VR (VR303) so that contrast terminal voltage(CP306) signal is 1.50
±
0.05 Vp-p.
(6) Adjust BRIGHT VR (VR304) so that potential between signal’s pedestal and 3 step is 2.10
±
0.05 Vp-p.
(7) Adjust CONTRAST VR (VR303) so that potential between signal’s pedestal and 10 step(white100%) is
2.90
±
0.05 Vp-p.
(8) Remove the resistance set between the killer terminal (CP308) and the VCC2-1 (CP344).
3. Notes
When unable to adjust using AC adaptor, use voltage regulator and supply power to be VCC-1-1 (CP149) =
5.0
±
0.05 V.
4. Connection diagram
(pedestal-10 step)
2.90V
±
0.05V
Figure2
L-PCB
VCC1-1
(CP105)
VG terminal
(CP322)
(Figure 2)
Digital oscilloscope
QV-8000SX
Killer terminal
(CP308)
VCC2-1(CP344)
Power supply