Electrical Adjustment Instructions - Sharp DV-NC150U Service Manual

ELECTRICAL ADJUSTMENT INSTRUCTIONS

NOTE: CBA AND PWB MEANS PRINTED WIRING
BOARD.
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 (9HSFL8A) (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
9HSFL8A Oscilloscope
Connections of Measurement Equipment
TP751
Main CBA GND
TP504
" or
Mode Input
-----
PLAY
(SP)
Spec.
6.5H 1H
(412.7 S 63.5 S)
Oscilloscope
CH1 CH2
Trig. (+)
1-8-1
Figure 1
EXT. Syncronize Trigger Point
CH1
1.0H
6.5H±1H (412.7µs±63.5µs)
CH2
Switching Pulse
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 (412.7µs±63.5µs) delayed position
from the rising edge of the CH2 head switching pulse
waveform.
0.5H
V-Sync
H9641EA