Casio EV-660C Service Manual page 13

5. Contrast, Bright adjustment
• Conditions
(1) Signals
Broadcasting system: I
Color system: PAL color bar
(2) Signal level
Input electric field: 70 ± 3 dBµ (terminated with 75Ω resistance), P/S = 7 dB
(3) Others
UK IF input (input electric field should be terminated with 75Ω resistance)
As to VIDEO signal, use signal source equivalent to TG7.
Supplying power should be VCC1-1 = 5.00 ± 0.05 V
• Adjustment
(1) Apply VCC2-3 (CP344) voltage on KILLER terminal (CP308) via 22 kΩ resistance.
(2) Triggering FRP signal (CP711), observe VB waveform (CP324) and adjust BRIGHT VR so that pedes-
tal-pedestal voltage becomes 5.0 ± 0.1[V].
(3) Adjust VR303 so that VB (CP324) waveform's pedestal - white peak voltage is 3.5 ± 0.1[V].
• Caution
(1) Make sure that waveforms are not distorted.
(2) After the adjustment, disconnect VCC2-3 voltage from the killer terminal.
(Reference: Use white 75% for PAL color bar.)
(3) Do not move BRIGHT VR until TINT and COLOR adjustments are completed.
• Block diagram
Signal
generator
Stabilizer
L-PCB
IF signal
CP308
B output
VCC1-1
— 11 —
VCC2-3
22 KΩ
Oscilloscope