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ELECTRICAL ADJUSTMENT INSTRUCTIONS
General Note: "CBA" is an abbreviation for
"Circuit Board Assembly."
NOTE:
1. Electrical adjustments are required after replacing
circuit components and certain mechanical parts. It
is important to do these adjustments only after all
repairs and replacements have been completed.
Also, do not attempt these adjustments unless the
proper equipment is available.
2. To perform these alignment / confirmation proce-
dures, make sure that the tracking control is set in
the center position: Press either "CHANNEL
"CHANNEL
" button on the front panel first, then
the "PLAY" button on the front panel.
Test Equipment Required
1. Oscilloscope: Dual-trace with 10:1 probe,
V-Range: 0.001~50V/Div.,
F-Range: DC~AC-20MHz
2. Alignment Tape (9HSFL6A) (Refer to "SERVICE
FIXTURE AND TOOLS" section.)
Head Switching Position
Adjustment
Purpose:
To determine the Head Switching position during
playback.
Symptom of Misadjustment:
May cause Head Switching noise or vertical jitter in
the picture.
Test point
Adj.Point
TP751(V-OUT)
VR501
TP504(RF-SW)
(Switching Point)
GND
(MAIN CBA)
Measurement
Tape
Equipment
9HSFL6A
Oscilloscope
Connections of Measurement Equipment
TP751
Main CBA
GND
TP504
Reference Notes:
" or
Playback the Alignment tape and adjust VR501 so that
the V-sync front edge of the CH1 video output waveform
is at the 6.5H±1H (416µs±64µs) delayed position from
the rising edge of the CH2 head switching pulse
waveform.
Mode
Input
-----
PLAY
(SP)
Spec.
6.5H 1H
(416 S 64 S)
Oscilloscope
CH1
CH2
Trig. (+)
1-8-1
Figure 1
EXT. Syncronize Trigger Point
CH1
1.0H
6.5H±1H (416µs±64µs)
CH2
Switching Pulse
0.5H
V-Sync
H9740EA
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