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9) Maximum AFM envelope output point check
(Hi-Fi model)
1. Playback the SP mode 3 MHz video signal and the
400 Hz AFM signal on the alignment tape.
2. Trigger the oscilloscope with the video switching
pulse, adjust the tracking control and check the
control pulse phase at the maximum video enve-
lope (A ch) output point.
3. Make sure the control pulse phase difference
among each maximum point of AFM envelope,
Ach and Bch is within + 3 ms with the above point
used as the basic reference.
Note:
¢ If the phase difference exceeds 3 ms, replace the upper
cylinder.
2. ELECTRICAL ADJUSTMENT
<Test equipment required>
Adjustment will be performed with the following test
equipment.
1. Color TV (Monitor)
2. Oscilloscope, 2 CHs, 15 MHz or higher with delay
system
. Frequency counter (7 digits or higher)
Millivoltmeter
Digital voltmenter
Tester (20 kQ/V)
Audio generator
Audio attenuator
oe
NAHE
YW
Alignment tapes
Part code: ST-C6: 70909409, ST-C7: 70909410
10. Alignment screw driver (jig)
11. Color pattern generator
12, Video sweep generator
<Color bar signal>
Color bar signals of 75% recorded on the alignment tapes
are shown in Fig. 2-1-1.
Horizontal syne
Color bar signal
Waveform
(75%)
Color bar pattern
Fig. 2-1-1
<Specified input and output levels, and impedance>
Video input:
Negative sync, standard composite
video sigan! 1 V(p-p), 75Q
Video output:
Same as the video input 1 V(p-p),
75Q.
Audio input:
308 mV(rms), more than 47 kQ2 (phono
type), more than 10 kQ (21 pin type)
Audio output:
308 mV(rms), less than 4.7 kQ (phono
type), less than 1.0 kQ (21 pin type)
<Alignment sequence>
Recorded the alignments in the sequence as shown inFig.
2-1-2.
Power System
Servo System
Logic System
Remote
Video
,
Control
Signal
Audio
System
System
System
Fig. 2-1-2
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