Daewoo DR-C912B, Service Manual

Page: 34 / 132

F. PLAYBACK PHASE ADJUSTMENT(FIG.
5.6)
PHASE GENERATOR(PG) SHIFTER determine the VIDEO HEAD
SWITCHING POINT when the TAPE is played back. If an adjust-
ment of the PHASE GENERATOR(PG) SHIFTER is not done pre-
cisely, There can be a HEAD SWITCHING NOISE or a VERTI-
CAL JITTER problem, vibration of the picture on the screen, not
good quality of picture in special play back.
a. Connect the PT01 on the MAIN CIRCUIT BOARD with a PATH
ADJ. FIXTURE.
b. Play back an ALIGNMENT TAPE(DN-2 : MON-SCOPE signal)
c. Connect the S/W PULSE TEST PIN on the PATH ADJ. FIX-
TURE with a CHANNEL-1 SCOPE PROBE.
d. Connect the VIDEO OUT on the MAIN CIRCUIT BOARD with a
CHANNEL-2 SCOPE PROBE (1V/div).
e. Control the PG VOLUME until the time interval between the
SWITCHING PULSE and the V-SYNC SIGNAL is within the
6.5H
– 0.5H as shown in Fig. 5.6.
G. ADJUSTMENT OF THE LINEARITY(FIG.
5.7)
a. Connect the PT01 on the MAIN CIRCUIT BOARD with a PATH
ADJ. FIXTURE.
b. Play back an ALIGNMENT TAPE(DN-2 : MONOSCOPE Signal).
c. Connect the FIXTURE S/W PULSE TEST PIN on the PATH ADJ.
CHANNEL-1 SCOPE PROBE.
d. Connect the VIDEO OUT on the MAIN CIRCUIT BOARD
with a CHANNEL-2 SCOPE PROBE (1V/div).
e. Adjust the VR CONTROL on the ADJ. FIXTURE until the
ENVELOPE signal is maximum while play back the ALIGN-
MENET TAPE.
f. Adjust the S/T GUIDE ROLLER until the envelope signal wave-
forms of the entrance and exit sides are as shown in Fig. 5-7.
32
ADJUSTMENT OF THE TAPE TRANSPORT SECTION
FIg.5.5 Adjustment of the X-POSITION
a: Max Output of Envelope
b: Min Output of Envelope
FIg.5.7 Adjustment of Linearity
Fig.5.6 Playback Phase Adjustment
S/W PULSE TEST PIN MAIN CIRCUTE BOARD
ENVELOPE TEST PIN MAIN CIRCUTE BOARD
Measurement Equipment OSILLOSCOPE
VR 595(PG SHIFTER)
MAIN CIRCUTE BOARD
Test Point
Adjustment
S/W PULSE TEST PIN PATH ADJ. FIXTURE
ENVELOPE TEST PIN PATH ADJ.FIXTURE
Measurement Equipment OSILLOSCOPE
VR CONTROL
PATH ADJ.FIXTURE
S/T GUIDE ROLLER TAPE TRANSPORT SECTION
Test Point
Adjustment