Bl Drive Voltage Adjustment; Vcom Ac Adjustment And Vcom Dc Coarse Adjustment - Casio QV-770 Service Manual

BL drive voltage adjustment

• Voltage supply
VCL0 (CP101)=5.0±0.05[V]
Apply 3.3 V ± 5% to PW.
(You can use an AC adaptor however, for the checking after repairs, apply above mentioned voltages.)
(1) Apply 5.0 ± 0.05 V to VCL0 and adjust VR900 so that CP901(VBL) will be 6.1 ± 0.1 V.
Notes: • Make sure that the current consumption is not abnormally large.
• CN920 is open.
VCL0
A
3.3 V
Power suppry
VCOM AC adjustment and VCOM DC coarse adjustment (PCB-LB)
• Voltage supply
VCC2 = 5 V ± 0.05 (V) (CP181).
VCC8 = 13.5 ± 0.05 (V) (CP180).
VEE2 = –15.0 ± 0.05 (V) (CP182).
(You can use an AC adaptor however, for the checking after repairs, apply above mentioned voltages.)
(1) Make sure that the amplitude of VCOM output (CP771) is 6.6 ± 0.3 V.
(2) Adjust VR770 so that the potential of VCOM output (CP711) will be 4.8 ± 0.2 V.
VCC8
Power
VCC2
suppry
VEE2
QV-770
PCB-LA
(CP101)
(CP901)
PW
QV-770
PCB-LB
(CP180)
(CP181
VCOM
(CP771)
(CP182)
— 18 —
VBL
high level
4.8 [V]
0 [V]
–1.8 [V]
oscilloscope
V
amplitude
6.6 [V]