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Adjustments - Casio TV-880B Service Manual & Parts List

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1. VCC2 adjustment, VCC2-3, VCC7, VEE1 voltage check
2. LLD coil adjustment
3. Free running frequency adjustment
4. Contrast adjustment
5. TINT pot adjustment
Preparations
1. Connect AVB (CP725) to GND.
2. Set SW100 on UHF mode.
Adjustment procedures
1. VCC2 adjustment, VCC2-3, VCC7, VEE1 voltage check
• Condition
Power supply: Vcc1-1 = 5.0 ± 0.05 [V]
• Adjustment
Apply 5.0 ± 0.05 [V] on Vcc1-1 (CP101).
Adjust VR100 so that Vcc voltage becomes 4.90 ± 0.02 [V].
• Checking
VCC2-3 (CP-105) = 3.87 ~ 4.13 [V]
VCC7 (CP103) = 36.0 ~ 44.0 [V]
VEE1 (CP104) = –4.5 ~ –5.5 [V]
2. LLD coil adjustment
• Conditions
(1) Signals
Broadcasting system: M/M
Color system: NTSC color bar
(2) Signal level
Input electric field: 40 ± 5dBµ (IF AGC full gain), P/S = 10dB
(3) Other conditions
US IF (Input electric field: terminated with 75-ohm resistance)
Power supply: Vcc1-1 = 5.0 ± 0.05 [V]
• Adjustment
Monitor video detection signal (CP238) via a low-pass filter of 100 kHz cutoff frequency and adjust
LLD coil T200 so that its DC level is minimum (waveform's amplitude is maximum).
(Reference: C= 1500 pF, R = 1 Kohm)
• Confirmation
There should be no waveform distortion (erroneous synchronization, etc.), under sensitivity (video
detector output level is abnormally small, etc.).
3. Free running frequency adjustment
• Conditions
(1) Signal
No signal (NTSC standard signal should be applied only at synchronous check)
(2) Signal level
Input electric field only at synchronous check: 70 dBµ (terminated with 75-ohm resistance), P/S = 10 dB
(3) Other conditions
US IF input only at synchronous check (input electric field with 75-ohm termination).
Connect SYF terminal (CP729) and VCC2-7.
Power supply: Vcc1-1 = 5.0 ± 0.05 [V]
Room temperature: 20 ± 10 [°C]

ADJUSTMENTS

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Kx-518b