Casio KX-787, Руководство по обслуживанию и список запасных частей

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5-4. 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 SHIFT key and MENU button simultaneously
2. Quickly press keys in the order of SHIFT key, SHIFT key and MENU key.
(2) Select / Execute GRAY SCALE (10 step). (NTSC)
(3) Trigger VG waveform (CP322) by FRP (CP300) signal to adjust as noted below.
(4) Adjust CONTRAST VR (VR306) so that contrast terminal voltage(CP302) signal is 1.50
±
0.05 V.
(5) Adjust BRIGHT VR (VR303) so that potential between signal’s pedestal and 4 step is 2.25
±
0.05 Vp-p.
(6) Adjust CONTRAST VR (VR306) so that potential between signal’s pedestal and 10 step is 2.85
±
0.05
Vp-p.
(7) Remove the resistance set between the killer terminal (CP308) and the VCC5 (CP520).
3. Notes
• Consecutively, execute 5-5. TINT setting adjustment.
• Make sure that waveforms are not distorted.
4. Connection diagram
D-PCB
VG(CP322)
Figure 2
Digital oscilloscope
Killer terminal
(CP308)
QV-2900
VCC5
22K
Ω
Power
Supply
Figure 2
pedestal level
2.25
±
0.05 [Vp-p]
(pedestal – 4STEP)