Sony AV-3420CE User manual

SONY:
SERVICE
MANUAL
AV-3420CE
VIDEOCORDER
REVISED 1
SONY CORPORATION

SONY:
SHRVICH MANUAL
AV-3420CE
VIDEOCORDER
SONY CORPORATION

Section
1.
TABLE OF CONTENTS
Title
GENERAL DESCRIPTION
T-1. Introduction oo... iceceecceeeeeeeeeee
1-2. Specifications ................cccceceeee eee
1-3. Location of Parts and Controls ....
1-4, Operation .........cscsccssncncosecreceeesoos
DISASSEMBLY
2-1. Cabinet Removal .............cccceeeeeee
2-2. Electrical Service ...........c.cccceeseeeee
2-3. Tape Transport Service ...............
POWER SUPPLY ALIGNMENT
3-1. Power Supply Adjustment ...........
3-2. Battery Meter Calibration ...........
SERVO SYSTEM ALIGNMENT
4-1. Alignment Sequence ..............0..
4-2. Equipment Required ............0.....
4-3. Adjustment Procedure..................
VIDEO SYSTEM ALIGNMENT
5-1. Equipment Required ...................
5-2. Alignment Sequence ............
5-3. Deviation Adjustment ................
5-4. Tape Path Check ..........cccceeececeeees
5-5. Modulavor Symmetry
Adjustment ......... cc eecesee see ees
5-6. Carrier Leak Adjustment .............
5-7. Monitor Level Adjustment ..........
5-8. Record Current Adjustment .........
5-9. Playback Preamplifier Frequency
Response Adjustment .............
AUDIO SYSTEM ALIGNMENT
6-1. Alignment Sequence ...............00
6-2. Equipment Required ..................
6-3. Audio Head Azimuth
Adjustment ......... cc eecceseee seen
6-4. Playback Level and Frequency
Response Adjustment ..............
6-5. Bias Oscillator Check «00.0.0...
Section
6-6.
6-7.
6-8.
Title Page
Record Bias Setting ................:0000 6-2
Bias Trap Adjustment .................. 6-2
Record Level Adjustment ............ 6-2
7. MECHANICAL SYSTEM MAINTENANCE
T-1. Introduction 2.0.0... cceeeeeeeeeeeee 7-1
7-2. Cleaning Heads and Slip-rings ...... 7-1
7-3. Video Head Replacement ............. 7-3
7-4. Audio/Control Head
Replacement — .......... cee ceeeeee eee 7-6
7-5. Stop Brake Adjustment ............... 7-7
7-6. Pinch Roller Pressure
Adjustment ..........ccccccsseececeneee 7-8
7-7. Tape Tension Brake Check .......... 7-8
7-8. Fast Forward Pulley
Adjustment ....... cece eeee scene ee 71-9
7-9. Take-up Torque Adjustment ....... 7-9
7-10. Sub-motor Replacement............... 7-10
8. CIRCUIT DESCRIPTION
8-1.
8-2.
8-3.
8-4.
8-5.
Video Circuit 8-1
Servo Circuit 8-2
Audio Circuit 8-7
Power Supply 8-8
Camera Remote Control Circuit ...- 8-8
9. TAPE TRANSPORT DESCRIPTION
9-1... Tape: Path <..As..2440 casi: 9-1
9-2. Tape Transport in Playback
MOG6® onccinceseeshedesand tere cttarsiane tase 9-2
9-3. Instant Stop Mechanism ............. 9-4
9-4. Tape Transport in the Record
MOdE sdsicccccsssvacvss ascot vesseesieekeet 9-5
9-5. Audio Dub Mechanism ............... 9-6
9-6. Tape Transport in the Fast
Forward Mode ............c:ceeeeeeeee 9-7
9-7. Tape Transport in the
Rewind Mode ..............::eeseee eee 9-8
10. SCHEMATICS AND EXPLODED
MIEWS coe eens biases 10-1
Block Diagram.............ccccccssesseeeeeees 10-1
Schematics Diagram................:.c0008 10-5
Exploded Views..............ccsscceseeeeres 10-7

SECTION 1
GENERAL DESCRIPTION
1-1. INTRODUCTION ‘
The Model AV-3420CE is a lightweight, compact,
portable Videocorder with a built-in three-way
power supply and may be operated from power,
a BP-20 battery, or a car battery. The-unit provides
high-quality video/audio record and playback func-
tions. Recorded material can be played back on
the camera viewfinder screen, a video monitor con-
nected with a VMC-1M cable or a conventional TV
receiver, using the RF Unit.
Two dc motors are used, one for the head
drum drive and the other for capstan servo, since
both head drum and capstan servo systems are
employed.
The recorded pattern on the magnetic tape
conforms to SONY AV-CE seires standards so that
tape interchangeability between all SONY AV-CE
seires video tape recorders should be maintained.
1-2. SPECIFICATIONS
Video recording Rotary 2-head helical scan sys-
system: tem, full field, composite video
signal based on CCIR TV
standards (supplied from the
AVC-3420CE Video Camera or a
monitor/receiver).
Track pattern: SONY AV-CE series track.
Tape Interchangeable with all other
interchangeability: tapes with SONY AV-CE series
standard track pattern.
30 minutes continuously with
a V-30H tape.
Recording time:
Tape speed: 163.22 mm +0.2%
0.5 ~ 2.0 V(p-p),synce negative,
Video input:
: 75 ohms, unbalanced.
Video output:
Resolution:
S/N ratio:
DC level supplied
to viewfinder
video input:
Audio input
(microphone jack):
Audio output
(earphone jack):
Audio overall
characteristics:
Maximum record/
playback time:
Charging time:
Power
requirements:
Dimensions:
Weight:
Accessories
supplied:
1.0 V(p-p), sync negative,
75 ohms.
More than 300 lines
More than 40dB
DC6V1t0.5V
-65 dB, 3,600 ohms, AGC
(0 dB=0.775 V) , unbalanced
-4dB, 1k ohms
100Hz~10kHz, S/N ratio
40 dB
Continuously with AC-3420CE
power supply or 30 minutes with
BP-20
6 hours to charge BP-20
DC, 12 V+1.2 V with BP-20 12.6 W
AC, 110, 127, 220 or 240 V
+10% with AC-3420CE
280 mm(W) x 157 mm(H) x
295 mm(D)
8.5 kg.
AC power adaptor AC-3420CE
Battery pack, BP-20
Empty reel, RH-5E
Earphone, CE-3
Monitor connecting cable,
VMC-IM
Polishing cloth
Splicing tape
Cleaning fluid
Shoulder bag
1-1

1-3.
LOCATION OF PARTS AND
CONTROLS
TRACKING control
CAMERA/TV select switch
EXT POWER IN connector
camera connector
TRACKING
control:
CAMERA/TV
select switch:
carrying handle
Video head tracking is con-
trolled by shifting the control
track pulse electronically in the
playback mode in order to ob-
tain tape interchangeability.
Set to the CAMERA position
when using the AVC-3420CE
camera. A monitor may be
1 Vip-p)
a ee 7 Vip-p}, 75 ohms
VD output to AVC-3420CE
in record mode
+12 Vdc +B power
to AVC-3420CE
Fig. 1-1
record lever
function lever
BATTERY meter
EARPHONE jack
MIC jack
Camera connector:
connected with a VMC-1M mon-
itor connecting cable and the
selector set to TV.
An AVC-3420CE camera or CVM
series monitor can be connected
(with a VMC-1M cable). Fig. 1-4
shows the camera connections,
Fig. 1-5 TV connections.
composite video input and output, to and from AVC-3420CE
audio input from AVC-3420CE in record mode,
—65 dB, high impedance
6 Vip-p),
75 ohms
JIL
HD output to AVC-3420CE
in record mode
Fig. 1-2 Camera connections with videocorder

1 Vp-p)
composite video output
to TV in pb mode
RF out jack;
EXT. POWER IN
connector:
MIC jack:
Fig. 1-3. TV connections with Videocorder
Output connector for the RF
modulator unit (optional). The
video output is converted to a
VHF signal by the RF modu-
lator and is fed to the TV
antenna terminals.
Accepts external power from
the AC-3420CE ac power supply.
Accepts an external microphone,
-65 dB, 3,600 ohms
+12 V regulated power output
13.2V input from
AC-3420CE
Fig. 1-4.
AC-3420CE connection
composite video input from TV in record mode
audio input from TV
—65 dB, high inpedance
audio output to TV
—2dB8, 1k ohms
EARPHONE jack:
BATTERY meter:
RECORD lever:
Function lever:
Time counter:
Video head:
SOUND DUB
knob:
_ Select the
Accepts an earphone for moni-
toring playback audio output.
-4dB, 1k ohms.
Indicates battery terminal volt-
age in record and playback
modes. The pointer reads be-
tween white and red areas when
the voltage drops to 11V dc.
The video and servo systems
are put into the record mode
by actuating switches on the
respective boards.
desired transport
operation by setting the me-
chanical links, idlers, belts and
. pullies.
Indicates the elapsed time in
minutes. Drive for this four-
digit counter is taken from the
capstan sub-roller.
SONY video head type H01-02
commonly used in SONY AV-
3620CE, AV-3670CE Video-
corders.
Puts the audio channel into the
record mode while the video
channel is in the playback mode.
1-3

Releases the pinch roller from
the capstan temporarily to pro-
duce a still-frame picture.
STILL knob:
Automatic shut-off Power to the VTR is shut off
switch: by a microswitch when tape
slackens or runs out.
1-4. OPERATION
1-4-1. Power Source
The AV-3420CE Videocorder operates from a
built-in rechargeable battery pack. Ac power is
supplied by connecting the AC-3420CE ac Power
Adaptor which also permits battery charging. Oper-
ation from a 12V car battery is also possible using
the DCC-2400 Car Battery Cord (optional).
Battery installation
1. Open the battery compartment cover by
turning the screw with a coin.
2.
Plug
the
cord
from
the
battery
pack
into
the
jack
inside
the
battery
compartment.
Fig. 1-5
3. Install the battery pack and close the com-
partment cover.
Battery life
A fully-charged battery allows approximately
30 minutes of continuous operation of both Video
corder and camera. The pointer of the BATTERY
meter shows battery condition when the Videocorder
is turned on; a white-zone reading shows that the
1-4
battery is in good condition, a red-zone reading
shows that the battery is discharged. The Video-
corder and camera will not perform properly with
a weak battery. If the pointer of the BATTERY
meter is in the red zone, recharge the battery
at once.
Note: The battery is fully charged when it
leaves the factory. However, an idle
battery will discharge slowly over a long
period of time. Therefore, the battery
may not yield a full 30 minute operation
when it is first put into service. Full
capacity will be restored, however, after
the first recharge.
Car battery operation
Insert the cigarette-lighter plug of the car
battery cord into the cigarette lighter socket in the
car and male plug of the other end into the EXT
POWER IN connector on the Videocorder. For
further details, refer to the instruction manual
included with the DCC-2400 Car Battery Cord.
Ac power operation
1. Plug the power cord of the AC-3420CE ac
Power Adaptor into an ac outlet.
2. Insert the round plug of the adaptor into the
EXT POWER IN connector on the Video-
corder.
3. Press the adaptor POWER switch on. The red
Pilot Lamp will light and power will be sup-
plied to the Videocorder.
(EXT POWER IN)
AC-3420CE
Fig. 1-6 AC-3420CE connection
1-4-2. Tape Threading
1, Place an empty reel on the Take-Up Reel
Spindle and a full reel on the Supply Reel
Spindle.

2.
3.
1-4-3.
Unwind about 70cm of tape and thread it
onto the .Take-Up Reel according to the
direction of the arrow.
Fig. 1-7 Tape threading
Turn the Take-Up Reel by hand to take up
any excess slack in the tape path.
Recording with The Video Camera
Insert the camera cable of the AVC-3420CE into
the Camera Connector of the Videocorder:
Plug the 10-pin connector into the Camera
Connector on the Videocorder by matching
the slot in the plug with the guide pin on the
receptacle. Turn the locking collar of the
cable clockwise until the cable locks firmly
into place.
Set the CAMERA/TV switch to CAMERA.
Press the Time Counter Reset Button to set
the Time Counter to (000). This counter
indicates recording time as well as the amount
of the tape used. When you read the counter
as.a time indicator, read it as follows.
1375.2 eesecces 13.5 minutes or 13 minutes
30 seconds
0.9... .ceceeee 0.9 minutes or 54 seconds
First, set the Record Lever to the REC
position and then the Function Lever to FWD
(before releasing the Record Lever). The
Record Lever will lock into place and the
Videocorder and camera will remain in the
Standby mode.
Adjust the camera to obtain a satisfactory
picture as displayed on the viewfinder.
6. To start the recording, press the Grip Switch
on the hand grip of the camera, or push the
Start Button at the right side of the lens
mount.
7. To monitor the sound, plug the earphone into
the EARPHONE jack on the control panel of
the Videocorder.. Sound picked up by the
microphone built into the camera will be
recorded simultaneously. Picture and sound
levels are automatically adjusted by the
SONY-MATIC recording system in the Video-
corder and camera.
8. -.To stop recording, press the Grip Switch on
the hand grip or the Start Button again. At
the end of the recording, set the Function
Lever to STOP.
1-4-4. Recording TV Programs
1. Connect the 8-pin connector on the SONY
video monitor to the 10-pin Camera Connector
on the Videocorder using a WMC-1M con-
necting cable (supplied).
video monitor
Fig. 1-8 Monitor. connection
2. Set the CAMERA/TV switch to TV.
3. Set the Time Counter to (000).
4. Turn on the monitor and set the TV/VTR
switch on the monitor to VTR.
5. Hold the Record Lever in the REC position
to place the Videocorder in the E-to-E mode.
Adjust the controls on the monitor for the
best possible picture.
6. Holding the Record Lever, set the Function
Lever to FWD. Video and audio recording
will start. No adjustment of video and audio
signal levels is required. ; |
|
15

7. To stop recording, set the Function Lever to
STOP.
Note: Television programs may be copyrighted.
Recording of such material, particularly
if for commercial purposes, may be
contrary to provisions of the United
States copyright laws.
1-4-5. Tape Playback
The playback picture can be viewed on the
camera viewfinder screen, a monitor screen, or a
conventional TV screen with appropriate accessories.
Note: When playing back a tape which has
been interrupted during the Record
mode, picture distortion may be ob-
served during the transitions.
Playback on the viewfinder screen
Connect the AVC-3420CE Camera to the Camera
Connector of the Videocorder and set the Function
Lever to FWD.
Playback on the monitor screen
Connect the monitor to the Camera Connector
using the VMC-1M connecting cable and set the
Function Lever to FWD.
Playback on a conventional TV screen
The output signal of the Videocorder is con-
verted to an ordinary TV (rf) signal by an optional
accessory RF Unit, which can be installed inside
the battery compartment. The rf signal is fed to
the antenna terminals of the TV set through the
Antenna Selector ANS-1, supplied with the RF Unit.
Battery Pack
Fig. 1-9 Battery and RF pack installation
1-6
1. Take the battery pack out of the battery
compartment and insert the RF Unit.
2. Replace the battery pack as before.
3. Connect the feed wire of the Antenna Selector
to the external antenna terminals (300 ohms)
of the TV set.
4. Set the ANT/VTR switch on the Antenna
Selector fo VTR. When the Videocorder is
not in use, the TV set may be operated as a
normal television receiver by setting the
ANT/VTR switch to ANT position and con-
necting the 300-ohm external antenna to the
antenna terminals of the Antenna Selector.
5. Plug the cord from the Antenna Selector into
the RF OUT jack on the Videocorder.
6. Set the TV channel selector to the channel to
which the RF Unit is set.
VHF antenna
e:
(RF OUT)
Antenna Seelector ANS-1
Fig. 1-10 Antenna connection
STILL playback
A stop-motion picture is obtained by pulling
the STILL knob down in the direction of the arrow.
To release the STILL mode, return the knob to its
normal position.
TRACKING adjustment
When playing back a tape recorded on a dif-
ferent AV-Series Videocorder, adjust the TRACKING
control should any noise appear in the picture.
For normal playback, set the red mark on the knob
to the center position.

1-4-6. Sound Dubbing
New
sound
(from
a
microphone,
tape
recorder,
phonograph,
radio,
etc.)
can
be
recorded
on
a
prerecorded tape.
1.
Connect
the
sound
source
to
the
MIC
jack
on
the
Videocorder.
2.
Play
back
the
prerecorded
tape
and
watch
the
playback
picture
on
the
viewfinder,
monitor,
or
television
receiver.
video monitor
connecting cable
VMC-1M
Fig. 1-11. Sound dubbing
3. When the desired position for dubbing sound
is reached, set the Function Lever to STOP.
4. Pull the SOUND DUB knob in the direction
of the arrow and then set the Function Lever
to FWD.
5. When dubbing is complete, set the Function
Lever to STOP.
| 4-4-7. Tape Erasing
Erasure of prerecorded tapes is accomplished
automatically as the tape first passes the erase head
then moves on to the video (recording) heads.
Should you desire to erase tape without
recording, run the tape in the record mode with
no signal source connected.
1-4-8. Battery Charging
The built-in battery pack can be recharged with
or without removing it from the Videocorder.
Charging the battery pack inside the Videocorder
1.
Connect
the
AC-3420CE
ac
Power
Adaptor
to
the
Videocorder
and
to
an
ac
outlet.
2. Press the POWER switch to turn on the
adaptor. The red Pilot Lamp will light.
3. Set the Function Lever of the Videocorder
to STOP. Charging will then be started and
the Charging Meter on the adaptor will indicate
charging condition. While charging, the pointer
remains in the black zone (CHARGING).
When the battery is completely charged, the
pointer stops at the end of the red zone
(FULL). About 6 hours is required for full
charging.
Charging the battery pack outside the Videocorder
1. Take the battery pack out of the Videocorder.
2.. Connect the AC-3400 adaptor to an ac outlet.
3. Insert the plug from the battery pack into
the Charging Jack (BATT) on the adaptor.
4. Press the POWER switch to turn on the
adaptor. Battery charging will start and the
Charging Meter will indicate charging condition.
Note: Two battery packs can be recharged
simultaneously, one inside and one out-
side the Videocorder.
When the Charging Meter stops at the
FULL position, the two battery packs
are fully charged. In this case, about
10 hours is required for full charging.
To check whether or not the battery is fully
charged, turn off the power, then turn it on again.
The pointer should swing down a little and in a few
seconds swing back to the FULL position. This
shows a completely charged battery.
1-7

SECTION 2
DISASSEMBLY
2-1.
CABINET
REMOVAL
2.
Remove
the
four
Phillips-head
screws
as
indi-
cated in Fig. 2-3 (B) and remove the RF
The cabinet may be removed by taking out unit housing and insulation sheet.
the eight screws indicated in Fig. 2-1 and Fig. 2-2.
Keep the cabinet lid on when removing these screws.
@RK4x6 2pcs
@B3x8 2pes
Fig.
2-1.
Fig.
2-3
(A)
The video, audio, and servo boards are mounted
on hinges. Remove four screws at the corners to
release the board so that both sides are accessible.
See Fig. 2-4.
Fig. 2-2.
2-2. ELECTRICAL SERVICE
Video, audio, and servo circuits are exposed for
service by removing the bottom reinforcement beam,
RF unit housing, and insulation sheet.
1. Remove the two Phillips-head screws that
secure the bottom reinforcement beam and
remove the beam. See Fig. 2-3 (A).
Fig. 2-3 (B)
|
|
:

2-3. TAPE TRANSPORT SERVICE
The tape transport mechanism is exposed for
service by removing the reel panel. Loosen the
screws indicated in Fig. 2-5, and remove the reel
panel.
S71 (servo) board
Al (audio) board
D1 (demodulator) board
remove knobs
The
front
control
panel
with
carrying
handle
can
be
removed
by
taking
off
the
four
Phillips-head
screws
at
the
ends
of
the
control
panel.
V1 (video) board
Fig. 2-4
loosen screws
Fig. 2-5
2-2

SECTION 3
POWER SUPPLY ALIGNMENT
3-1.
POWER
SUPPLY
ADJUSTMENT
Test
Point:
Q902
collector.
Adjust
for:
Meter
pointer
reads
between
Test
Point:
Q902
emitter
the red
and
white
region
Adjust
for:
+9V
dc
;
when
power
supply
is
11
V
de
Adjustment:
R907
Adjustment:
R912
Procedure:
Procedure:
1.
Connect
VOM
to
Q902
collector.
1.
Disassembly
AC-3420CE
and
connect
it
to
VTR.
2.
Check
that
the
input
voltage
is
12V
~
13.5
Vdc,
2.
Connect
VOM
to
Q902
collector
of
VTR.
3.
Reconnect
VOM
to
Q902
emitter.
3.
Adjust
AC-3420CE
output
adjustment
(R17)
for
an
11V
d
ding.
4.
Adjust
R907
for
9V
dc.
ote
ae
4. Adjust R912 so that the battery meter reads
between the red and white regions of the scale.
3-2.
BATTERY
METER
CALIBRATION
Readjust
AC-3420CE
(R17)
for
original
setting
of
14.6V
output.
pointer R17
Fig. 3-1 Fig. 3-2 AC-3420CE
3-1

SECTION 4
SERVO SYSTEM ALIGNMENT
41. ALIGNMENT SEQUENCE
The servo system alignment sequence is shown
in Chart 4-1.
DRUM FREE-RUNNING SPEED
ADJUSTMENT (Section 4-3-1)
TV-VD LOCK PHASE AND HUNTING
ADJUSTMENT (Section 4-3-2) -
60PG COIL POSITION ADJUSTMENT
(Section 4-3-3)
30PG COIL POSITION ADJUSTMENT
(Section 4-3-4)
PLAYBACK SERVO CHECK
(Section 4-3-5)
Chart 4-1 Servo system alignment
4-2. EQUIPMENT REQUIRED
Monitor: SONY CV monitor
Frequency counter:
Oscilloscope:
TV camera: SONY model AVC-3420CE
camera
Monitor connection SONY model VMC-1M cable
cable:
Power supply: AC-3420CE or BP-20
4-3. ADJUSTMENT PROCEDURE
In TV record mode, the servo should lock to
the TV vertical sync signal. The free-running speed
of the head drum is 12,650 Hz.
4-3-1. Drum Free-Running Speed Adjustment
Test Point: TP-601
Adjust for: 12,650 Hz +10 Hz
Adjustment: R621
Signal source: None
Equipment Required:
Frequency Counter
Procedure:
1. Disconnect cable from TV-CAMERA connec-
tor at the monitor.
Set TV-CAMERA Select switch to TV.
Thread tape on VTR.
a te!
Check for +9V +B voltage.
5. Connect frequency counter to TP-601 of the
servo board.
6. Set up the record mode and check the fre-
quency counter reading.
7. Adjust R621 so that the frequency counter
reading is 12,650 Hz + 10 Hz.
4-3-2. TV-VD Lock Phase Adjustment and
Hunting Adj.
Test Point: TP-704 Servo board
Adjust for: Correct servo lock phase
Adjustment: R731 (lock phase), R732
(hunting)
Signal source: Telecast signal
Equipment Required:
1. Oscilloscope
2. Monitor
Procedure:
1. Connect the monitor with a VMC-1M cable.
2. Set the TV-CAMERA Select switch to TV.
3. Connect scope to TP-704; set up the 2 V/cm,
5 ms/cm range.
41

4. Thread the tape and set up the record mode.
5. Adjust R731 so that the PG pulse appears
midway between the positive and negative
peaks. See Fig. 4-1.
6. Stop the VTR. Pull the REC Lever and
measure the time required to stop the PG
pulse on the rectangular pulse. If it takes
more than 6 seconds, adjust R732.
4-3-3. 50 PG Coil Position Adjustment
Test Point: TP-708 (CH-1), TP-301 (CH-2)
Adjust for: 50 PG pulse at the center of
channel overlap.
Adjustment: 50 PG Coil
Signal source: None
Equipment Required:
1. Video Alignment Tape or Prerecorded Tape
2. Oscilloscope
Procedure:
1. Thread a SONY video alignment tape or any
prerecorded tape that is recorded by a
correctly-aligned VTR.
2. Connect the scope CH-1 probe to TP-708 and
the CH-2 probe to TP-301. TP-708 is on the
Servo board and TP-301 is on the Demodulator
board.
50PG coil 25PG coil
Fig. 4-2.
42
a
a
ince
Fig. 4-3.
3. Set the scope horizontal time base to 5 ms/cm.
Sync on CH-1 only.
4. Set up the playback mode.
5. Adjust scope controls to observe both signals.
Then set the scope MODE SWITCH to the
CHOP position. Pull out the SX magnifier
and adjust the HORIZONTAL POSITION to
observe the vertical blanking interval.
6. Bend the tip of the 50 PG coil with pliers and
adjust the coil position so that maximum rf
output is obtained in the overlap period.
See Fig. 42 and Fig. 4-3.
4-3-4. 30PG Coil Position Adjustment
Test Point: TP-304 (CH-1), TP-708 (CH-2)
Adjust for: 50 PG leads VD by 8H+1H
Adjustment: 25 PG coil
Signal source: TV telecast signal
Equipment Required:
1. Oscilloscope
2. Monitor TV
Procedure:
1. Connect scope CH-1 probe to TP-304 on the
“D1” board and CH-2 probe to TP-708 on “‘S1”
board. Set scope time base to 5ms/em. Sync
the scope externally from TP-703.
Connect monitor.
Set TV-CAMERA Select switch to TV.
i
Set up record mode.
5. Set the scope MODE SELECT switch to the

CHOP position. Pull out the 5X magnifier
and adjust
HORIZONTAL POSITION to
observe the vertical blanking interval.
6. Adjust the 25
PG coil so that the 50 PG pulse
leads the VD pulse by 8 H+1H. See Fig. 44.
ae of! 20.5 H
(
ae
|
fl
Fig. 4-4.
4-3-5. Playback Servo Check
Test Point:
Check for:
Adjustment:
Signal source:
TP-706
Servo locks in center of pull-
in range.
None
None
Equipment Required:
1.
Video Alignment tape or prerecorded tape
2. Oscilloscope
Procedure:
1. Connect scope to TP-706. Set up the 2V/cm,
2ms/cm ranges.
2. Thread the alignment tape.
3. Set up the playback mode.
4. Check to see that the PG pulse locks in the
center of the trailing edge of the rectangular
pulse. If not, perform Sec. 4-3. TV record mode
speed adjustment. Check also that Q719, Q720
emitter dc potential is between 3.5 V~4.5 V
dc.
Fig. 4-5.
4-3.

SECTION 5
VIDEO SYSTEM ALIGNMENT
The video system alignment procedure is shown 5-3. DEVIATION ADJUSTMENT
in Charts 5-1 and 5-2.
(including 1. Clamp level adj. 2. PB output
5-1.
EQUIPMENT
REQUIRED
level
adj.
3.
Input
level
adj.
4.
White
clip
adj.)
1.
Monitor
TV:
Test
Points
and
TP-104
(clamp
level).
.
R128
2.
Monitor
Connecting
cable:
VMC-1M
eillustmients:
TP-304
(PB
output
level)
3.
Oscilloscope;
2
nn
R343
4.
Video
Camera:
AVC-3420CE
TP304(
Video
input
level)
5.
Tape:
SONY
video
alignment
and
blank
tape
thy
een
R106
: TP-102
(White
clip
level)
wdeaty
sais
R127
Adjust
for:
3.8
MHz
to
5.2
MHz
maxi-
5-2.
ALIGNMENT
SEQUENCE
;
mum
deviation
clipped
-
at
40%
over
white
peak.
Signal
source:
Telecast
signal
DEVIATION ADJ.
(Sec.
5-3)
including
Equipment
Required:
1. Oscilloscope
2. Monitor TV 2 we
3. SONY video alignment tape or any prerecorded
tape that has been recorded on a VTR known
to be in good condition.
a. Clamp level adj.
b. PB output level adj.
c. Input level adj.
d. White clip adj.
These adjustments interact somewhat.
TAPE PATH CHECK
(Sec. 5-4)
MODULATOR SYMMETRY ADJ.
(Sec. 5-5)
CARRIER LEAK ADJ. (Sec. 5-6)
MONITOR LEVEL ADJ. (Sec. 5-7)
Procedure:
1. Set the TV-CAMERA Select switch to the
TV position.
2. Connect scope to TP-104.
3. Thread a blank tape.
4. Set up the record mode with no input signal.
5. Adjust R128 for 19 pulses as indicated on
the scope screen. 19 pulses can be measured
as follows.
a. Adjust scope time base for:0.5us per divi-
sion (calibrated).
b. Set scope controls to obtain a stable trace.
Set R128 to produce 19 complete cycles
in ten divisions.
6. Connect scope to the arm of R128 (movable
slider of R128).
7. Adjust sync tip clamp level as follows.
a. Set scope input to DC, horizontal time
base to 10us/cm and vertical deflection to
1V/cm. .
b. Confirm that the VTR is in the record mode.
c. Adjust scope STABILITY to observe a
RECORD CURRENT ADJ. (Sec. 5-8)
PB PREAMPLIFIER ADJ. (Sec. 5-9)
horizontal trace, and VERTICAL POSITION
so that the trace is positioned on the second
Chart 5-1 division from the bottom.
5-1

R128 movable arm
Fig. 5-1
d. Connect a monitor set up to receive an
off-the-air telecast signal.
e. Check to see that the sync tip of the
composite signal sinks below the second
division (See Fig. 5-2) by approx. 0.5V.
Measure the exact voltage by which the
sync tip sinks below the champ reference
level set in Step 7-c (Fig. 5-2). See Fig. 5-3.
Fig. 5-3 Sync tip level shift
f. Disconnect the monitor. Keep the VTR
in the record mode. :
g. Adjust scope STABILITY to observe a
horizontal trace on the same position as
seen on Fig. 5-2.
10.
12.
13.
14.
15.
16.
17.
18.
19.
h. Adjust R128 so that the horizontal trace
on the scope moves up by the voltage
measured in Step 7-e (Fig. 5-3). See Fig. 5-4.
Fig. 5-4 Clamp level
Connect scope to TP-104. Set time base to
0.5us/cm, and check that approx. 22 rectan-
gular pulses per 10 divisions is seen on the
scope. Sync tip clamp level is now set to
3.8 MHz.
Note: No-signal frequency is about
4.4 MHz (22 cycles) as a result of these
adjustments, but sync tip frequency
will be set correctly to 3.8 MHz.
Connect scope to TP-304. Set up 5 ms/cm range.
Connect a monitor.
Play back the video alignment tape.
Adjust R343 (video output level) for 1.0 V(p-p).
Output level is now set to 1.0 V(p-p).
Thread a blank tape instead of the alignment
tape.
Record a telecast signal for approx. 15 seconds.
Play back the tape and check the video level.
If video level is other than 1V(p-p), adjust
R106.
Turn
R106
slightly
CW
if
the
video
level is less than 1.0 V(p-p).
Record the telecast signal again and check
the video level. Readjust R106 until video
level is 1.0V(p-p). This completes maximum
deviation adjustments (3.8 MHz to 5.2 MHz).
Set up the record mode using a telecast signal.
Connect scope to TP-102.
5-2
|
|
|
|
|
q
|
|

20. Adjust R127 (white clip) so that the extreme
white peaks of the waveform are clipped at
40% of “‘A” volts as shown in Fig. 5-5.
40% of “A” volts
a
.. Fig. 5-5 White clip
5-4. TAPE PATH CHECK
CAUTION
Do not try to adjust any components that affect
the tape path. Serious deficiencies in performance,
such as poor interchangeability, will result if tape
path is set improperly. If checks show adjustments
are required, return the unit to a SONY FACTORY
SERVICE BRANCH.
1. Thread a blank tape.
2. Set up the playback mode.
3. Check the following:
a. The tape should run in the center of tape
guides, the sub-pinch roller and pinch roller
without curling or buckling.
b. The core of the Erase Head and Audio/CTL
Head must extend an equal amount above
and below the tape.
c. The tape should ride flush against the Tape
Guide Band.
d. The tape path in the fast forward and
rewind modes should be the same as in
the playback mode.
4. Make a recording and play back the tape.
5. Connect the scope to TP-301. Sync the scope
externally by TP-708. Check that a reasonably
flat rf envelope is observed. If the rf envelope
decreases by more than a factor of 2 at every-
other vertical field, clean the video heads or
replace the video head assembly.
5-3
5-5. MODULATOR SYMMETRY ADJUSTMENT
Test Point: TP-103 .
Adjust for: ' Waveform symmetry:
Adjustment: ’ R137 and C119
Signal source: None
Equipment Required:
1. Dual-trace Oscilloscope
Procedure:
1. Connect both scope probes (CH-1 and CH-2)
to TP-103. Set mode selector to ALTER.
Invert polarity of channel 1. Set time base
to 0.5us and expand sweep to display 2 or 3
square waves.
2. Set up record mode with no input signal.
3. Adjust scope VERTICAL POSITION to over-
lap the two signals.
4. Adjust for equal pulse width with C119 and
for waveshape symmetry with R137.
5-6. CARRIER LEAK ADJUSTMENT
Test Point: . Monitor
Adjust for: Minimum ‘carrier leak
Adjustment: R315 and R337 —
Signal source: Video alignment tape or test
pattern
Equipment Required:
1. Monitor
2. Video alignment tape or a video camera