Sharp DV-NC100X, Service Manual

Page: 20 / 117

1-8-1
H9740EA
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
" or
"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 Mode Input
TP751(V-OUT)
TP504(RF-SW)
GND
VR501
(Switching Point)
(MAIN CBA)
Tape
Measurement
Equipment
Spec.
9HSFL6A Oscilloscope
Connections of Measurement Equipment
Oscilloscope
Main CBA
CH1 CH2
Trig. (+)
GND
TP504
TP751
PLAY
(SP)
-----
(416 S 64 S)
6.5H 1H
ELECTRICAL ADJUSTMENT INSTRUCTIONS
EXT. Syncronize Trigger Point
1.0H
CH1
CH2
Switching Pulse
V-Sync
0.5H
6.5H
±
1H (416
µ
s
±
64
µ
s)
Figure 1
Reference Notes:
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 (416
µ
s
±
64
µ
s) delayed position from
the rising edge of the CH2 head switching pulse
waveform.