Vcc3, Vcc5 Voltage Check La-Pcb; Vcc2 Adjustment And Vcc7, Vcc8, Vee2 Voltage Check; Vco Free Run Frequency Adjustment - Casio QV-770 Service Manual

VCC3, VCC5 voltage check PCB-LA
• Voltage supply
CP151 = 5.0 ± 0.05 V.
(You can use an AC adaptor however, for the checking after repairs, apply above mentioned voltages.)
(1) Apply 5.0 ± 0.05 V to CP150.
(2) Make sure VCC3 (CP160) is 3.3 ± 0.1 V and VCC5 (CP152) is 5.0 ± 0.15 V.

VCC2 adjustment and VCC7, VCC8, VEE2 voltage check

• Voltage supply
VCL0(CP101)=5.0±0.05V.
(You can use an AC adaptor however, for the checking after repairs, apply above mentioned voltages.)
(1) Apply 5.0 V ± 0.05 V to VCL0 and adjust VR100 so that VCC2 will be 5.0 ± 0.02 V.
Notes: • VCC7 = 7.3 ~ 8.3 [V], VCC8 = 12.0 ~ 14.0 [V]
• VEE2 = –12.3 ~ –16.7 [V]
In addition, disconnect the power and make sure all output voltages are 0 V.

VCO free run frequency adjustment

• Voltage supply
VCC2=5 V ± 0.05 (V) (CP181).
VCC8 = 13.5 ± 0.05 (V) (CP180).
VEE2 = –15.0 ± 0.05 (V) (CP182).
Connect CP705 (CSY) and CP700 (GNP).
(You can use an AC adaptor however, for the checking after repairs, apply above mentioned voltages.)
(1) Monitoring CP710 (HDB) with a frequency counter, adjust VR720 so that the frequency will be 15.734
± 0.1 [KHz].
Notes: • Disconnect CP705 and CP700, then connect PCB-LA and make sure CP705 (CSY) and CP710
(HDB) are synchronized.
• Keep room temperature at 20 ± 10°C.
VCC2
VCC8
Power suppry
VEE2
PCB-LA
PCB assy
QV-770
PCB-LB
(CP181)
(CP180)
CS
(CP182)
(CP705)
CSY
HDB
(CP705) (CP710)
— 17 —
CSY
oscilloscope
HDB
frequency
counter