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Adjustment procedures (EV-660D)
1. VCC2 adjustment, VCC7, VCC6, VCC5, VEE1 voltage check
•
Condition
(1) Signal
No signal
(2) Other conditions
Power supply: Vcc1-1 = 5.00
±
0.05 [V]
•
Adjustment
Apply 5.00
±
0.05 [V] on Vcc1-1.
Adjust VR100 so that Vcc2 (CP108) voltage becomes 4.80
±
0.02 [V].
•
Checking
VCC7 (CP105) = 27.1 ~ 33.4 [V]
VCC6 (CP106) = 18.0 ~ 20.0 [V]
VCC5 (CP107) = 11.0 ~ 13.0 [V]
VEE1 (CP109) = –12.0 ~ –10.0 [V]
•
Block diagram
2. LLD coil adjustment
•
Conditions
(1) Signals
Broadcasting system: I
Color system: PAL color bar
(2) Signal level
Input electric field: 46
±
3 dB
µ
(IF AGC full gain), P/S = 7 dB
(3) Other conditions
UK IF (Input electric field: terminated with 75
Ω
resistance)
As to VIDEO signal, use signal source equivalent to TG7.
Power supply: Vcc1-1 = 5.00
±
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).
•
Confirmation
There should be no waveform distortion (erroneous synchronization, etc.), under sensitivity (video detector
output level is abnormally small, etc.).
•
Block diagram
V
Digital
Voltmeter
L-PCB
Stabilizer
VCC1-1
VCC7
VCC6
VCC5
VCC2
VEE1
VCC1-1
IF signal
L-PCB
Adjust to minimize the DC level.
Oscilloscope
DC IN
Detector OUT
Signal
generator
Stabilizer
Low-Pass Filter
