Casio EV-660C Service Manual page 12

3. Free running frequency adjustment
• Conditions
(1) Signal
No signal (PAL standard signal should be applied only at synchronous check)
(2) Signal level
Input electric field only at synchronous check: 70 ± 3 dBµ (terminated with 75Ω resistance),
P/S = 7 dB
(3) Other conditions
UK IF input only at synchronous check (input electric field with 75 Ω termination).
Connect SYF terminal (CP725) and GND.
Power supply: Vcc1-1 = 5.00 ± 0.05 [V]
Room temperature: 20 ± 10 [°C]
• Adjustment
Monitoring HDB (CP705) with a frequency counter, adjust VR710 so that the frequency is 15.625 ± 0.1 [kHz].
• Caution
(1) Disconnect the wire between SYF terminal. Applying IF signal make sure that synchronization is normal
on the display.
• Block diagram
Signal
generator
Stabilizer
4. VCOM AC and VCOM DC coarse adjustment
• Conditions
(1) Signals
Broadcasting system: I
Color system: PAL color bar
(2) Signal level
Input electric field: 70 ± 3dBµ (terminated with 75Ω resistance), P/S = 7 dB
(3) Others
UK IF input (input electric field should be terminated with 75Ω resistance)
Use VIDEO signal equivalent to TG7.
Power supply should be Vcc1-1 = 5.00 ± 0.05V.
• Adjustment
(1) Confirm that the amplitude of VCOM output (CP750) is 6.0 ± 0.3 [V].
(2) Adjust VR730 so that Low level voltage of VCOM output (CP750) is 2.4 ± 0.2 [V].
• Block diagram
Signal
generator
Stabilizer
SYF
IF signal
L-PCB
VCC1-1
L-PCB
IF signal
CP750
VCC1-1
— 10 —
GND
HDB
Frequency
Counter
Oscilloscope
2.4 V
GND