Vcom Dc Adjustment - Casio QV-3500EX Service Manual & Parts Catalogue

3-5. VCOM DC adjustment

1. Preparation
(1) AC adaptor or stabilizer.
(2) Photo sensor/ Photo sensor amp (C2719)/L.P.F
(3) Digital oscilloscope.
2. Adjustment and checking
(1) Turn the power on while pressing SHIFT and MENU keys simultaneously. (TEST MODE)
(2) Push SHIFT
(3) Choose 50 PERCENT GRAY and execute it.
(4) Monitor the photo sensor amplifier output via a low-pass filter of cutoff frequency 60Hz.
Monitoring the oscilloscope screen, adjust VR321 to minimize 60Hz ripple waveform.
3. Notes
Perform these adjustments when you replace LCD module or PCB L.
Photo diode
S1153
LCD
QV-3500EX
(Reference) Easy adjustment
(1) Shot a monoscope pattern with the camera and adjust VR321 so that the best 10-step gradation is
taken.
10-step gradation
SHIFT MENU keys in order rapidly. (TEST MODE 1)
Photo Sensor Amp
C2719
Monoscope pattern
L.P.F
— 21 —
Oscilloscope
Minimize the
ripple components
10-step gradation