Sanyo HV-DX300A Service Manual page 50

H. Adjustment of the Wave Form of DRUM
Entrance / Exit (Fig. 5.8)
S/W PULSE TEST PIN
Test Point
ENVELOPE TEST PIN
Measurement Equipment OSILLOSCOPE
VR CONTROL
Adjustment
S/T GUIDE ROLLER
a. Connect the PT01 on the MAIN CIRCUIT BOARD with
a PATH ADJ.FIXTURE.
b. Play back an ALIGNMENT TAPE
c. Connect the S/W PULSE TEST PIN on the PATH ADJ.
FIXTURE 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. Turn the VR CONTROL on the PATH ADJ.FIXTURE
clockwise or counterclockwise until the signal shape of
ENVELOPE has the constant thickness.(Fig.5.8)
f. Adjust the S/T GUIDE ROLLER if the thickness of the
ENVELOPE signal is not uniform.
FIg.5.8 Fine adjustment of the ENVELOPE at the DRUM
ENTRANCE/EXIT
I. REVIEW PLAY(Fig. 5.9)
S/W PULSE TEST PIN
Test Point
ENVELOPE TEST PIN
Measurement Equipment OSILLOSCOPE
VR CONTROL
Adjustment
S/T GUIDE ROLLER
a. Connect the PT01 on the MAIN CIRCUIT BOARD with
a PATH ADJ.FIXTURE.
b. Play back an ALIGNMENT TAPE
c. Connect the S/W PULSE TEST PIN on the PATH ADJ.
FIXTURE with a CHANNEL-1 SCOPE PROBE.
d. Connect the VIDEO OUT on the MAIN CIRCUIT-
PATH ADJ. FIXTURE
PATH ADJ.FIXTURE
PATH ADJ.FIXTURE
TAPE TRANSPORT SECTION
PATH ADJ. FIXTURE
PATH ADJ.FIXTURE
PATH ADJ.FIXTURE
TAPE TRANSPORT SECTION
BOARD with a CHANNEL-2 SCOPE PROBE (1V/div).
e. Make the VR CONTROL on the PATH ADJ. FIXTURE
to the center to maximize the ENVELOPE signal.
f. Play back the REVIEW mode about 15 second and alter
the mode to PLAY MODE.
g. Check whether the ENVELOPE waveform restore to its
original form within 3 second when the REVIEW mode is
changed to PLAY mode.
h. If the requirement of "g" is not satisfied, Check the run-
ning status of tape on the lower part of TGUIDE POST
and adjust the S/T GUIDE ROLLER precisely
FIg.5.9 Waveform change when the modealtered
(REVIEW
J.Checking AUDIO Output Waveform (Adjustment
.
of AC HEAD TILT & Height)
Test Point AUDIO OUTPUT
Measurement Equipment AUDIO LEVEL METER
a. Connect the AUDIO output jack with an AUDIO LEVEL
METER.
b. Playback an Alignment Tape
c. Check if the AUDIO output signal level is over -9~-
3dBm.
d. If the requirement of "c" is not satisfied, readjust the AC
HEAD TILT and the HEIGHT until the AUDIO output is
maximized. (Fig. 5.2, 5.3)
23
PLAY)
AUDIO OUTPUT JACK