Sony AV-3600 User manual

AV-3600
V1DEOCORDER
SONY CORPORATION

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CIRCUIT-DIAGRAM-SERVICE in GERMANY
SCHALTPLANE -SERVICEANLEITUNGEN -BEDIENUNGSANLEITUNGEN
SERVICE MANUAL
SERVICE MANUAL
AV-3600
VIDEOCORDER
SONY CORPORATION
SCHALTUNGSDIENST LANGE Berlin 47 Postfach 47 12 20 Tel. [phone] PO
Postgiroamt Berlin-West Kto.Nr.7.26 60 -100

SERVICE MANUAL
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U. S. PAT, 3,175,034
3,215,772
3,431,353
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SONY CORPORATION
@1970

TABLE OF CONTENTS
Section Title Page Section Title Page
1. GENERAL DESCRIPTION
1-1 .Introduction 1-1
1-2. Specifications 1-1
1-3. Operating Instructions 1-2
1-4. Input/Output Connections .... 1-3
2. CIRCUIT DESCRIPTION
2-1. Video Circuits 2-1
2-2. Servo Circuits 2-3
2-3. Audio Circuits 2-6
2-4. Camera Control Circuits 2-6
2-5. Power Supply Circuits 2-6
System Block Diagram 2-7
3. DISASSEMBLY
3-1. Cabinet Removal 3-1
3-2. Removal of Control and
Reel Panels 3-1
4. MECHANICAL MAINTENANCE
4-1 .Precautions 4-1
4-2 .Cleaning Heads
and Slip Rings 4-1
4-3. Lubrication 4-1
4-4. Drive-Belt Replacement 4-2
4-5. Drive Pulley Adjustment 4-2
4-6. Video Head Replacement 4-3
4-7. Tape Tension Brake Check 4-7
4-8. Reel Table Height 4-8
4-9. Audio/Control
Head Replacement 4-8
4-10. Take-up Idler Adjustment 4-8
4-11. Rewind Idler Replacement .... 4-9
4-12. Brake-System Adjustment .... 4-11
4-13. Motor Replacement 4-13
4-14. Record Button Latch Linkage. .4-15
4-15. Automatic Shutoff
Switch Adjustment 4-16
4-16. Capstan Bearing and
Shaft Replacement 4-17
4-17. Capstan Deck Assembly
Adjustment 4-19
4-18. Pinch Roller 4-19
4-19. Microswitch Maintenance
and Adjustment 4-20
5. VIDEO SYSTEM ALIGNMENT
5-1. Maximum Deviation
Adjustment 5-2
5-2. Carrier Leak Adjustment 5-4
5-3. Record Current Adjustment ...5-4
5-4. Playback Preamplifier
Adjustment 5.5
6. SERVO SYSTEM ALIGNMENT
6-1, Free-Running Speed Check. .. . 6-2
6-2. Vertical Sync
Separator Check 6-2
6-3. 2:1Frequency
Divider Check 6-2
6-4. 30-Hz Pulse Adjustment 6-3
6-5. 30 PG Pulse Lock
Phase Adjustment 6-3
6-6. Servo Response-Time
Adjustment 6-3
6-7. Playback Servo Check 6-4
6-8. 30 PG Pulse Position Check ... 6-4
6-9. 30 PG Pulse Phase Check 6-6
6-10. Servo-Reference Delay
MV (Rec) 6-6
6-11. Servo-Reference Delay
MV(PB) 6-7
6-12. Tracking Control Check 5.7
6-13. Vertical Sync Former Check . . $-8
7. AUDIO SYSTEM ALIGNMENT
7-1. Audio/CTL Head Azimuth
and Tilt Adjustments 7-2
7-2. Playback Level Adjustment. ...7-2
7-3. Line Output Level Calibratioa .7-2
7-4. Bias/Erase
Oscillator Check 7-3
7-5. Audio Record Bias Setting .... 7-3
8. POWER SUPPLY ALIGNMENT
8-1. Power Supply Adjustment ...
9. PRINTED CIRCUIT BOARD AND
SCHEMATIC DIAGRAMS
9-1. V2 Mod &Rec/PB Amp
.
9-2. VI Limiter &Demod ...
S- 3
!- 5

Section Title Page
9-3. SV Servo 9-7
9-4. AAudio .9-9
9-5. R2, RVoltage Regulator .... 9-11
9-6. SY3 Vertical Sync Former . . 9-13
Schematic Diagram insert
10. ELECTRICAL PARTS LIST
10-1. V2 Video Amp, Modulator
&Rec/PB Amp .... 10-1
10-2. VI Limiter &Demodulator .10-3
10-3. SV Servo 10-4
10-4. AAudio 10-6
10-5. R/R2 Voltage Regulator ....10-7
10-6. SY3 Sync Former 10-7
10-7. Frame 10-8
Section Title Page
11. EXPLODED VIEWS WITH PART NUMBERS
11-1. Cabinet Assembly 11-2
11-2. Reel Panel and Sash 11-3
11-3. Head Drum Assembly 11-4
11-4. Capstan Deck
Assembly and Motor 11-5
11-5. Tape Transport 111-6
11-6. Tape Transport 211-7
11-7. Record Switch Linkage 11-8
11-8. Power Supply Block
and Microswitches 11-9
11-9. Connector Panel and Others ... 11-10
11-10. Hardware Parts List 11-11

SECTION 1
GENERAL DESCRIPTION
1-1. INTRODUCTION
This manual provides service information for the
SONY AV-3600 Videocorder. It does not include
information pertaining to special equipment applica-
tions, nor does it include instructions for performing
factory-type repairs.
1-2. SPECIFICATIONS
Type EIA Japan type-1 video tape
recorder
Video Recording System
Recording system :Rotary two-head slant-track
scanning
Recording signal: 2:1interlace composite video
signal based on American TV
standards using EIA or industrial
sync.
Modulation system: Frequency modulation
Interchangeability: Recordings made on all AV series
Videocorders are interchangeable.
Operating Characteristics
Tape: 1/2 inch (12.7 mm) width on
7-inch reel maximum.
Tape speed: 7.5 inches per second (19.05 cm
per second)
Recording time: 60 minutes (continuous) using
SONY V-32 tape
30 minutes (continuous) using
SONY V-31 tape
Rewind time: Within 7minutes for afull
7-inch reel
Operating position; Horizontal only
Video Characteristics
Input:
Camera input:
0.5 to 2V(p-p), sync negative,
75 ohms unbalanced, internally
terminated
0.5 to 2V(p-p), sync negative,
75 ohms unbalanced, internally
terminated, for SONY AVC series
cameras.
Output: 1.0 V(p-p), sync negative, for
a75-ohm load, unbalanced.
Resolution: Greater than 300 lines
Signal-to-noise
ratio: Greater than 40 dB
Audio Characteristics
Microphone input: —65 dB, 600 ohms, unbalanced
TV input: -20 dB, high impedance, un-
balanced
Auxiliary input: -0 dB, high impedance, un-
balanced
Line output: dB, 10 kohms, unbalanced
Frequency range: 80 to 10,000 Hz
Signal-to-noise
ratio: Greater than 40 dB
Flutter and wow: Less than 0.2%
Camera Control Signal
V. D.: 60 Hz, negative pulse, 2V(p-p,
with 75 ohm load), unbalanced
Rf Signal (When the RF unit is used)
Rf output: 80 dB ('0 dB =1fiV), 75 ohms
General
Semiconductors: 5IC s, 56 transistors (including
5FETs) and 32 diodes
Power
requirements: 117 Vac (±10%), 60 Hz (±0,5%)
Power
consumption 60 watts
AC outlet: 117 V, 500 watts maximum
Ambient
temperature: 32°F(0°C)to 104°F(40°C)
Dimensions: 15-3/4" (W) x9-1/16" (H) x
13-3/16" (D)
(400 x233 x335 mm)
Weight: 33 lb (15 kg)
1-1

1-3. OPERATING INSTRUCTIONS Playback Mode
PRECAUTIONS
1. To prevent accidental damage or needless wear
to the video heads, observe the following.
a. Do not operate the motor (Function Lever
in FAST FORWARD, PAUSE, FORWARD,
or REWIND position) unless tape is threaded
properly on the machine.
b. Never attempt to thread the tape while the
motor is running.
c. At the end of record or playback operations,
set the Function Lever to STOP.
d. Avoid leaving the motor running for extend-
ed periods while the tape is stationary.
e. Do not operate the Function Lever if the
tape is slack anywhere in the tape path.
2. To prevent erasure of aprerecorded tape, do not
put the VTR in the record mode while the prere-
corded tape is on the machine. Tape erasure takes
place when the RECORD button is down and the
Function Lever is in the FORWARD position.
Preliminary Setup
1. Press the POWER button. The pilot lamp will
light.
2. Set the Tape Counter to 000 by pressing the re-
set button at the right of the counter.
3. Set the CAMERA/LINE/TV Selector according
to the input signal.
Record Mode
1. To put the VTR into the "E-to-E" mode, press
the red RECORD button down until it locks in
the "down" position. The red RECORD indicator
button will light.
2. To start the recording, hold the RECORD button
down while moving the Function Lever to
FORWARD. This locks the RECORD button
down in the record position. The automatic gain
control system adjusts video and audio input
levels automatically.
3. To stop the recording, move the Function Lever
to the STOP position. The RECORD button is re-
leased and the VTR reverts to the playback mode
1. The VTR operates in the playback mode as long
as the RECORD button is not depressed. Note
that the monitor will display asnowy raster as
the playback circuits have no input signals.
2. To play aprerecorded tape, set the Function
Lever to FORWARD. The monitor will display
the pictures previously recorded on the tape.
3. For stop-action, set the Function Lever to
PAUSE. The tape transport will stop and the
monitor will display astill picture.
4. To skip over aportion of tape, move the Function
Lever to the FAST FORWARD position. The
tape will advance rapidly. To resume normal play-
back, set the Function Lever to PAUSE and then
to FORWARD. Tape will move again at the
normal playing speed.
5. To stop the playback operation, set the Function
Lever to STOP.
SKEW Control
Picture distortion in the upper part of the screen
may be corrected by turning the SKEW control.
This knob automatically returns to its center position
when the RECORD button is pressed.
TRACKING Control
Noise in the picture due to improper tracking may
be corrected by turning the TRACKING control. For
normal playback, turn the knob fully counterclock-
wise to the FIX position.
SoundDubbing
To insert (dub) new sound onto aprerecorded
tape, proceed as follows.
1
.
Connect amicrophone (or other audio source) to
the VTR. Refer to Section 1-4 for audio input
connection.
Note: When amicrophone is connected, the
auxiliary input at the AUX. IN jack is
disabled.
2. Set the CAMERA/LINE/TV selector to CAMERA
or LINE.
3. Play back the prerecorded tape. When the portion
on which the new sound is to be added is seen on
1-2

the monitor screen, push the AUDIO DUB switch
down. Sound dubbing will start.
4. At the end of the dub, set the Function Lever to
STOP.
Playback on aConventional TV
Aconventional TV receiver can also be used for
playback display by adapting the RF Unit (optional)
to the Videocorder.
1. Remove the cover of the RF Unit compartment.
2. Insert the RF Unit (RFU-53W or 54W whichever
channel is inactive in your area) into the com-
partment and connect the Videocorder, Antenna
Selector and TV receiver as shown in Fig. 1-1.
wantenna selector
4
AV-3600
\
to [RF OUT] nto antenna
terminals
J
©
Fig. 1-1. RF Unit connections
3. Set the ANT/VTR switch on the Antenna
Selector to VTR.
4. Set the TV channel selector to the channel to
which the RF Unit is set.
5. Set the Videocorder to the playback mode.
6. Adjust the fine tuning knob for the best picture.
1-4. INPUT/OUTPUT CONNECTIONS
Figure 1-2 shows all input and output terminals,
and output-signal characteristics. Normal connections
to the monitor are made at 8-pin jack marked TV.
Normal camera connections are made at the 6-pin
CAMERA receptacle. Signal and power connections
to other accessory equipment are as shown.
A. Power Cord Receptacle [AC IN 117V 60 Hz].
Connects to athree-wire (parallel-ground) ac
receptacle.
B. Power Output Receptacle, unswitched [AC OUT
117V 500W] .Line output to power amonitor or
camera. Max. rating 500 watts.
C. TV-Monitor Jack [TV] .Provides all signal con-
nections to and from the monitor. See detail.
D. Fuse [1.5 A] Contains a1.5-ampere fuse.
E. Audio Out Jack [LINE OUT] .Provides an addi-
tional audio-output feed to supply playback
monitors or other audio components. Signal
level: dB (0.775V) across high impedance. This
jack is in parallel with pins 1and 5(5 grounded)
of the TV jack.
F. Auxiliary Input Jack [AUX. IN]. Provides an
alternative audio input for high impedance micro-
phones, studio feeds, record players, and other
audio sources. Signal level requirements: -20 dB
across high impedance.
G. Microphone Input Jack [MIC IN]. Signal feed
point for aSONY microphone or other micro-
phone with similar characteristics. Signal level re-
quirements: -60 dB, 600 ohms, single ended.
H. Camera Jack [CAMERA]. Provides video and
sync connections to the camera. See detail.
I. UHF Input Connector [VIDEO IN]. Pro\ides
video input connection for acamera or TV
monitor equipped avideo-output UHF con-
nector.
J. UHF Output Connector [VIDEO IN]. Pro-
vides an additional video-output feed to supply
amonitor having avideo-input UHF connector.
K. RF Output Jack [RF OUT]. Supplies output
to the antenna terminals of aconventional TV
receiver when the RF unit is used.
L. RF Unit Compartment [RF UNIT]. The
RF Unit (optional) is inserted into this com-
partment.
1-3

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SECTION 2
CIRCUIT DESCRIPTION
Refer to the block diagram on page 2-7 and the
schematic diagram on page 9-15.
2-1. VIDEO CIRCUITS
Video information is recorded on the tape in the
form of afrequency-modulated carrier. The video
circuits on the VI and V2 Boards process the video
signal during record and playback operations.
In the record mode the video input is supplied to the
V2 Board, where it is gain-controlled automatically,
clamped, pre-emphasized, white-clipped, dark-clipped,
fm modulated, and supplied to the record amplifier.
The video output signal from the record amplifier
is supplied to the video heads through the slip rings
and is recorded on the tape.
In the playback mode the recorded signals from the
rotary heads are fed to the playback preamplifier
on the V2 Board. The amplified video outputs are
mixed together and these continuous fm signals are
fed to the VI Board.
The circuits located on the VI Board include a
limiter, differentiator, rectifier and demodulator. The
video output from the VI Board is areproduction
of the original video signal.
Video Input
PIN 4of the TV (8-pin) jack for TV recording.
PIN 1of the CAMERA (6-pin) jack for camera
recording.
UHF connector for LINE (auxiliary) video input.
Video Amplifiers andAGC-QlOl to Q104
The incoming video signal is supplied to the first
video amplifier Q102 through apre-emphasis circuit
consisting of R101 and CI 01. The input signal level
for Q102 is controlled by AGC amplifier Q101
(FET), without manual video level control. Q102
and Q103 amplify the video signal and feed it to
Q104. Asample of the video signal at the emitter
of Q104 is fed to the peak detector consisting of
CI 08, D101, and D102. The output of the rectifier
is apositive dc voltage that is proportional to the
peak white component of the video signal. This dc
voltage controls the conduction of AGC amplifier
Q101 and this controls the amount "of input signal
to Q102. R101 and C101 accomplish pre-emphasis so
that the AGC circuit is effective for high frequency
signals.
Low Pass Filter-L102, L103, CI 13
The low-pass filter rejects the video signals at the
high end of the band, such as the 3.58 MHz color
subcarrier and the 4.5 MHz audio i-f signal.
Deviation Setting and Clamp-Q105, R121, D103,
R126
The output of the low pass filter is supplied to
Q105 through R121.
Rl 21sets the video signal level to Q105 so that the
following fm modulator produces an fm signal of 1.4
MHz deviation, from 3.2 MHz to 4.6 MHz. D103
clamps the sync tip of the composite video signal
to the reference voltage picked off at the arm of
R126. This reference voltage sets the sync tip (or no-
signal) frequency of the fm modulator. R126 is set to
establish the sync tip carrier frequency of 3.2 MHz.
Pre-emphasis and amplifiers-Ql 06, Q107, Rl30,
R131, C118
The dc clamped video signal is applied through
Q106 to the pre-emphasis circuit consisting of R130,
R131, and CI 18 to improve the signal-to-noise ratio
of the video information, and then to grounded-base
amplifier Q107. Base-bias voltage for Q107 is sup-
plied from the arm of R126.
White Clipper, Dark Clipper, and Mod. Driver-
Q1Q8, D104yR137, D107, R155
The pre-emphasized video signal contains over-
shoot in both the positive and negative directions.
D104 limits the maximum positive signal (wkite
peaks) of Q107 to the voltage picked off at the arm
of R137. D107 clips negative spikes. Video from
D104 is fed to the modulator through modulator
driver Q108.
Modulator~Q109, QUO
The modulator is afree-running symmetrical
multivibrator. Frequency control is achieved "fcy
returning both bases to the low-impedance source
of modulating voltage-the emitter of QlOS-
through R140. Frequency varies from the tip-
of-sync value of 3.2 MHz to amaximum 4.6 MHz
for peak white signals. R148 and CI 22 are adjusted
to obtain asymmetrical output waveform (equal
pulse durations and slopes for each half cycle).
Waveform symmetry is important as it determines
2-1

the extent to which carrier energy can be removed
from the demodulated signal. The modulator output
is approximately 4.0 V(p-p) at TP-106. The push-
pull modulator output is converted to a single-ended
feedbyTlOl.
Record Amplifiers-Q21 0, Q211
The fm signals from the modulator is applied to
record amplifiers Q210 and Q211. Q210 drives the
video heads through driver transformer T203. The
record amplifiers operate in the Record mode only,
as B+ is switched off in all other modes. R225
adjusts the recording current applied to the video
heads for optimum recording level. Video Heads A
and Bare connected in parallel to the secondary of
transformer T203. R217 equalizes the recording cur-
rent of Video Head Bto that of Video Head A.
Video Heads
Aslip-ring and brush assembly couples recording
current to Video Heads Aand B. The Video Heads
supply signals during playback operations. The angle
between the heads is 180° ±20".
to the following playback amplifiers during positive
excursions of the switching waveform. While output
of Video Head Ais gated, the output of Video Head
Bis blocked from the playback amplifiers. This is
done as follows:
When Q206 is cut off (Q205 ON), the cascode
amplifier of Channel Bcan not amplify Head B
output because of the high impedance (L202) in the
source of Q202. The conditions described above are
reversed with each 180° rotation of the head drum
by the signals from two 30 PG coils mounted on the
scanner. Thus, the output of each head is alternately
coupled to Q207 and combined into acontinuous
rf signal without any noise. The timing relation of
the switching pulses is shown in Fig. 2-1.
Equalizing amplifiers-Q208, Q209
The rf signal from Q207 is amplified by Q208 and
fed to the limiters through Q209. The collector
circuit of Q208 contains aresonant circuit consisting
of R211, L204, and C211 which provides playback
equalization. R211 and L204 set the resonant fre-
quency to about 3.5 MHz for correct playback
equalization.
Playback Amplifiers~Q201, Q203, Q202, Q204
Outputs from the video heads are coupled through
T201 and T202 (load ratio 1:1) to their respective
playback amplifiers. The low-noise cascode amplifier
Q201 (Q202, FETs) and Q203 (Q204) amplify
the weak signals. Aresonant circuit in the gate of
Q201 (Q203), consisting of T201 (T202), R201
(R202), and C201 (C202), resonates with the react-
ance of the head and increases the output from the
head at the resonant frequency to provide high fre-
quency compensation for head-to-tape characteristics.
Inductor L203 in the collector of Q203 (Q204) keeps
the dc collector level constant, and also forms atrap
with R205 to keep the audio bias/erase signal out
of the playback amplifiers during audio dub oper-
ations.
Switchers and Mixer-Q205, Q206, Q207
The Channel Aswitching transistor, Q205, is
employed in the source of Q201. Similarly, Channel
Bemploys switching transistor Q206 in the source
of Q202. The states of Q205 and Q206 are always
opposite. For example, when Q205 is saturated,
Q206 is cut off by the opposite-phase rectangular
switching pulses from FF401 (hybrid IC). When
Q205 is ON, the source of Q201 is shorted to ground,
so that Q201 can amplify rf signals. Output from
Head Ais amplified by Q201 and Q203, and routed
Limiters-Q301 to Q305, D301 to D310
The limiter stages eliminate amplitude fluctuations
caused by variations in head-to-tape contact. Limiting
is accomplished by the four diode pairs with interstage
amplification supplied by transistors Q301 to Q305.
Each diode conducts when the signal across it reaches
about 0.4 V(p-p) in the forward direction. Thus, trie
signal is limited in both directions to 0.8 V(p-p).
In the last stage D307/D308 (D309/D310) conduct
when the signal exceeds 0.7 V(p-p) signal, so that
2.8 V(p-p) is developed across the combination
D307 and D308 (D309 and D310). R305 in the base
circuit of Q302 is adjusted for acorrect operating
point to produce asymmetrical limiter output
waveform.
Demodutetor-D311, D312, Q306, LPF
The input to the demodulator is differentiate! t>y
R324 and the primary winding of T301. The jusJi-
pull output of T301 is applied to a frequency dopier
consisting of apair of pulse detectors D311ar»d
D312. They conduct on alternate half cycles to
produce two positive output pulses per input qcl^e.
Thus, carrier frequency is effectively doubled ar»d
placed outside the video passband. By integratirJg
the pulse output in the low-pass filter that foiovws
Q306, avideo output is obtained that is proportional
to pulse frequency. R326 is set to balance the jul^e
2-2

output of the frequency doubler. R329 and C315
reduce high-frequency gain to provide de-emphasis.
Video Amplifiers-Q307 to Q310
Video output from the low-pass filter is amplified
by Q307 and Q308 and then supplied to the video
output stages (to Q309 for the rf adaptor and TVjack
and to Q310 for VIDEO OUT.) R335 adjusts the
video output level and is adjusted to provide 1.0 V
(p-p) at the output terminals.
2-2. SERVO CIRCUITS
Basic principles of the servo and pulse system of
the AV-3600 are shown in Fig. 2-1.
The rotational speed and angular position of the
heads are controlled by means of amagnetic-brake
servo system. In this system the head table is belt-
driven at aspeed greater than 30 rps by asyn-
chronous motor. The servo system controls a
magnetic brake that slows the head table to precisely
30 rps.
Each video head begins to scan the tape about
10 H(horizontal lines) before the vertical sync
interval (rf signal) supplied to the video head and
ends its scan about 10 Hafter the next vertical sync
interval.
During TV record operations, separated 60-Hz
sync signals serve as the timing reference for the
servo. The arrival of every other 60-Hz sync pulse is
compared with a30-Hz pulse generated by 30 PG
coil Bin the Rotary-Head Drum Assembly. See
Fig.2-1. The comparator system of the servo controls
brake current to maintain the correct time reference
between the sync pulse and the 30 PG pulses.
In playback, the recorded control track pulses
serve as the reference for the servo system.
Sync Separator and Pulse Amplifier-Q402, Q403
Asample of composite video signal from Q104
on the V2 Board is fed to Q402. Sync is separated
from the composite video signal by Q402, and
horizontal sync pulses are removed by the following
integrator circuit (R424 through R426, C412 through
C414). The separated vertical sync pulse is amplified
by Q403 and then triggers monostable multivibrator
MM402. During playback, Q401 amplifies control
pulses from the recorded tape.
Frequency Divider-MM402, R433
Anegative sync pulse from Q403, coupled through
D404, flips the monostable multivibrator MM402
(hybrid IC) into the unstable state. Pulse duration,
determined by R433, is about 24 milliseconds, long
enough for the circuit to ignore the next 60-Hz
sync pulse. Thus the multivibrator runs at 30-Hz and
is triggered by every other pulse. The 60-Hz sync
pulse is fed to Pin 2of MM402, and the divided
30-Hz pulse is obtained at the same Pin 2. Since the
sync signal is referenced to the 30-Hz signal from
30 PG coil B, 60-Hz sync pulses must be halved.
Waveshaper-MM404, R441
During playback, the output from MM402 is
supplied to monostable multivibrator MM404 via
SW7-4 and D406, and triggers MM404 (hybrid IC).
This multivibrator shapes the 30-Hz pulse from
MM402 to form 30-Hz pulses with a50% duly cycle
so that areference dc level may be obtained for the
following gate circuit. R441 sets the duty cycle (pulse
duration).
When the TRACKING control is ON (in playback)
the output of MM403 triggers MM404.
Integrator and Gate-R446, C426, C427, Q405
The output from MM404 is integrated by R446
and C426 (or C427 in playback) to form the wave-
shape shown at TP-410 of Fig. 2-1. The integrated
pulse is fed to the gate circuit, Q405. The gate is
turned on by the 30 PG pulse (from Q404) applied
to its base. For the duration of 30 PG pulse, the
integrated pulse applied to the emitter of Q405 is
sampled and appears at the collector, and charges
C432. Thus, the output of the gate is a function of
the arrival time of the 30 PG pulse. The integrated
pulse is gated on its leading edge by the 30 PG
pulse as shown in TP-410 in Fig. 2-1. If the 30 PG
pulse is early (servo too fast) the output of tlie
gate is less. Alate 30 PG pulse (servo too slow)
results in greater output. During record the in-
tegrated 30-Hz pulse rises with ashort time con-
stant (R446 xC426) as shown by the solid line in
TP-410 in Fig. 2-1. Therefore, aslight deviation of
the 30 PG pulse from its stable position on the 30-Hz
integrated pulse ramp causes alarge variation in ga/te
output for the servo. This results in quick servo
response, and also minimizes the variation of control
track signals recorded on the tape.
In playback, the integrated 30-Hz pulse rises nth
afaster time constant (R446 xC427) as shown fc>y
the dotted line in TP-410 in Fig. 2-1. Adeviation of
30 PG pulses (from control track signals on the taptf)
on the ramp causes less of avariation in the ga*e
output resulting in aslower servo response compared
23

with that in record and absorbs control track signal
deviations caused by wow and flutter.
30 PG Coils AandB
Two PG coils are mounted on the scanner (upper
drum) 180° apart. 30 PG coil Ais at the front of
the scanner and 30 PG coil Bat the rear. Both PG
coils are connected between B+and ground through
R401 and R402 respectively, and biased at about
2Vdc. Their fields are cut once per revolution by
asingle vane (pole piece) mounted on the rotating
head platform. Each 30 PG coil produces apulse
shown in Fig. 2-1.
Switching Pulse Former and 30 PG Pulse Shaper-
FF401
Negative going pulses of the two 30 PG coils are
coupled to bistable multivibrator FF401 (hybrid IC)
through D401 and D402. Apulse supplied to Pin
1flips FF401 and apulse supplied to Pin 4flips it
back. The outputs from Pins 2and 3, identical 30-Hz
square waves opposite in phase, are applied to
switchers Q205 and Q206 through integrators R406/
C205 and R407/C206, respectively. Asample of the
output from Pin 2is supplied to adifferentiator
consisting of R408 and C404. The negative spike
from the differentiator, which is in phase with the
pulse generated by 30 PG coil B, triggers MM401 to
supply the gate circuit.
30 PG Delay Multivibrator-MM401,R412, R413
Monostable multivibrator MM401 (hybrid IC)
delays the 30 PG pulse (from 30 PG coil B) and sets
the timing interval between the vertical sync signal
(during record) and the 30 PG pulse from coil B.
Since the sync signal serves as the timing reference,
the time delay advances the angular position of the
rotating-head platform with respect to the video
signal. MM401 produces apositive pulse of 930 /xs
duration during record and one of 1.9 msec dura-
tion during playback for each input pulse. This
output pulse is differentiated by C428 and R448 and
the negative spike, delayed by an amount equal to
the pulse duration of MM401, is supplied to the gate
circuit. The pulse duration, i.e. the delay time of
MM401, is selected by SW7-8 according to the mode
of operation. Thus, the differentiated pulse is able
to gate the integrated reference 30-Hz pulse at the
proper position on the ramp to produce the same gating
output in record or playback regardless of the dif-
ference in 30-Hz pulse waveshapes. See Fig. 2-1.
R412 and R413 adjust the pulse duration (delay
time) of MM401 in record and playback operations
respectively.
Delayed 30 PG Pulse Shaper
The delayed 30 PG negative pulse is amplified
and shaped by Q404. Output of Q404 feeds the gate
circuit.
Dc Holder and Amplifiers~C432yQ406, Q407,
R451, R454
Gate output appears across C432, which holds
the level until the following gate output. C432 sets
the gate-to-source voltage of Q406 and thus es-
tablishes Q406 output. Direct coupled dc amplifiers
Q406 and Q407 supply control current to the servo
brake coil. R45 1sets the response time of the servo
system by controlling the amount of feedback
current from Q407 to Q406 and is adjusted for
minimum response time without servo hunting. A
large amount of feedback reduces the ac gain of the
amplifiers and prevents servo hunting but it increases
the response time. R454 adjusts the dc gain of Q406
to obtain optimum braking current.
Control Track Head-CTL Head
During record, an output from monostable multi-
vibrator MM404 is applied to the Control-Track Head
(CTL Head). This records a30-Hz timing reference
to be used during playback in place of the vertical
sync pulse.
Control Track Pulse Amplifier-Q401
In playback, control track pulses picked up by
the CTL head are amplified by Q401 and coupled to
Q402 through anoise filter consisting of R418,C409,
andC410.
Tracking Control Mutivibrator~MM40
3
When the TRACKING control (R007) on tlie
Control Panel is pulled out during playback, the 50-
Hz pulse from MM402 is coupled to MM404 via tlie
tracking multivibrator, MM403 (hybrid IC). Mono-
stable multivibrator MM403 compensates for O)
variations in control track information between re-
corders, (b) tape stretching, and (c) tolerances in
physical placement of the CTL head. For this pur-
pose, MM403 delays the control track pulse arid
adjusts the timing interval between the video informa-
tion and the recorded control track pulse. The del^y
time can be varied with the TRACKING control
R007, which varies the pulse duration of MM403.
2-4

TP-404
syncsep. in
(CTL pulse in
the PB mode)
s,"V~Y~V~V
TP-406
pulse amp
TP-407
freq. divider
out
TP-408
tracking MV
(Dotted line
shows variable
range)
TP-409*
waveshaper
TP-410
(Dotted line
shows the
waveforms in
the PB mode)
Q405BASE
delayed
gating pulse
Q404 BASE
TP-403
30 PG delay
MV
(PB switching relations)
TP-412
switching pulse ™
Q206 BASE
switching pulse
for Bhead
Q20S BASE
switching pulse
for Ahead x
TP-201 I
TP-305
video output
8H
\.
2
W~^ y\S
8H
(reference
head)B
position of
video heads
pole piece
Waveshaper MM404 is triggered by the trailing edge of the tracking
MV output (above), when the TRACKING control is ON.
Fig. 2- /. Timing reiations ofpulse and servo system,
(waveforms are not drawn to scaie)
ie

2-3. AUDIO CIRCUITS 2-4. CAMERA CONTROL CIRCUITS
Record
Audio input feeds through C501 to preamplifiers
Q501 and Q502. The gain of Q502 is automatically
controlled by AGC amplifier Q503 (FET). R510 and
C506 provide negative feedback. Output of Q502 is
applied to the driver amplifier Q504 and then to the
audio output stage Q505. Asample of the output is
fed to the audio level detector consisting of C528,
C535, D501 and D502. The output dc voltage of the
detector controls the conduction of AGC amplifier
Q503. Thus Q503, in the feedback loop from the
output stage Q505 to the input Q501, controls the
amount of feedback current and the gain of Q501.
R521 in the source of Q503 adjusts the audio output
level.
Output from Q505 is applied to the audio record/
play head. In addition, rf bias produced by the bias/
erase oscillator Q506 is applied to the head through
trimmer capacitor C532. This adjusts the bias signal
level supplied to the head. Bias trap L502 and C525
eliminates the high-frequency bias signal from the
audio output circuit. L501 and C512 in the base of
Q504 and L503 and C519 in the collector of Q505
provide pre-emphasis.
Playback
In playback, the feedback network in the pre-
amplifier is altered to take the path through R513,
R514, and C510, This network changes preamplifier
characteristics to provide de-emphasis and equali-
zation. Preamplifier output appears across R515,
which sets the drive to the output stage for playback.
The driver and output stages, Q504 and Q505, func-
tion in the same way for both record and playback.
The bias/erase oscillator Q506 is not energized as
B+to this stage is switched off in playback.
The sync pulse former on the SY3 Board shapes
the 60-Hz ac sine wave into vertical sync pulses to
lock the horizontal deflection oscillator in the
camera. The sine wave signal from the secondary
winding of T001 is supplied to C902. Negative peaks
are clamped to ground by D901 and C902. The
clamped signal is amplified by Q901, differentiated
by R905 and C904, and supplied to the pulse ampli-
fiers Q902 and Q903. Q903 feeds negative vertical
sync pulses through the CAMERA connector CN4
to the camera.
2-5. POWER SUPPLY CIRCUITS
The ac line voltage is stepped down by the power
transformer T001 and supplied to full wave recti-
fiers D601 and D602. Dc output from the rectifiers
is filtered by C601 and applied to the series regulator
Q601, Transistor Q603 compares asample of the
output voltage, picked off at R604, with areference
voltage supplied by Zener diode D603. Achange in
output voltage, detected by Q603, results in achange
in conduction of Q602 and Q601 that offsets the
original voltage shift.
B+ for the RF adaptor is fed through asimple
regulator consisting of R005 and D001.
Sets bearing Serial Number 12,201 and higher
have aextra regulator for the rf adaptor consisting of
Q604 and Q605 on an R2 board. This regulator
operates the same way as the main regulator.
2-6

TV
LINE
CAMERA
video input
\
video head A
video head B<+-
30 PG coil A
30 PG coii B
CTL head -*
0102-0104 Q105
pre-
emphasis video
amp
Q101
LPF -* buffer <
AGC *^
—
-% to Q402
0210,0211
REC
^n
PB?
REC,
REC
amp
V2
C
0201 0203, 0205 207-Q209
equalize |
<i
PBpre-
amp
PB°0202
0204,
PB pre-
amp
0206
FF401
wave
shaper
amp
PB
MM401
30 PG ^
delay MV
0401
PBr
REC?
CTL
amp
*% from 0104
I0402, 0403
jblEC
MM402
5PB
sync
sep/puise
amp LP
freq
divider
audio input
(TV, LINE or-
MIC)
audio head
audio erase
head
video erase
head
dummy coil'-
REC 0501, 0502
J* AUDIO
DUB

Q106, Q107 Q108 (1109, QUO
>video
amp pre-
emphasis white, dark clip mod
driver FM
mod —
»
2305
fcr doubter
freq _^ de- _^
emphasis
Q306 Q307, Q308 Q309
amp &.
LPF i~*1video
amp video
out
Q310
ard
video
out
.video output
"^ (to TV)
RF
adaptor
RF output
(to TV ANT.
terminal)
video output
SY board
(tracking
switch)
T>ON
-I ^^o—
o
PB MM404 Q405
MV inte-
grator
Q406, Q407
gate -* dc
amp "jbra/re co/7
Q505
out
D502
to
I
tctor
->* audio output
Aboard
5+
Q601-Q605
regu-
lator
Q901-Q903
VD
former
SY3 board
_^AC117V
60 Hz
VD signal
(to camera)
Fig. 2-2. System block diagram
2-7

SECTION 3
DISASSEMBLY
3-1. CABINET REMOVAL
1. Turn the VTR (with cabinet lid) upside down on
apadded bench as shown in Fig. 3-1.
Remove these screws
Remove these screws
Remove fuse holder cap
Fig. 3-1. Cabinet removal
2. Remove the four Phillips-head screws from the
bottom of the cabinet as shown in Fig. 3-1. Also,
remove the two Phillips head screws on the side
of the cabinet.
3. Remove the fuse holder cap (and fuse) on the
connector panel.
4. Lift off the cabinet.
3-2. REMOVAL OF CONTROL AND REEL
PANELS
1. Pull out the SKEW control and the TRACKING
control knobs.
2. Loosen the two screws at the back of the Head
Cover. It is not necessary to remove these screws
completely. Lift off the Head Cover.
3. Loosen the set screw in the Function Lever
(Allen wrench, 0.1* across the flats). Pull off the
lever.
4. Remove the screw securing the Pinch Roller Re-
tainer. Remove the Pinch Roller. Be careful not to
lose the Pinch Roller Spacer.
5. Loosen the two screws "A"* and remove the four
screws "B" as shown in Fig. 3-2.
6. Lift off the Control and Reel Panels.
Fig. 3-2. Removal of Control and Reel Parnl
These are captive screws and need not be re-
moved completely.
3-1

SECTION 4
MECHANICAL MAINTENANCE
4-1. PRECAUTIONS
Machine compatibility (interchangeability of tapes
between machines) depends upon very close mechan-
ical tolerances in the tape path. The tape path is fac-
tory-adjusted and should not require realignment
under normal circumstances. Do not attempt adjust-
ment of the tape guides or the tapered guides. If
mechanical damage requires replacement and/or ad-
justment of the guides in the tape path, return the
unit to aSONY FACTORY SERVICE CENTER for
repair.
4-2. CLEANING HEADS AND SLIP RINGS
Noise in the picture during playback is usually
caused by an accumulation of debris in the video
heads. In some cases, half the picture may be noisy
(split screen); in severe cases, video output may be
lost.
To clean the heads, stop the machine, remove the
tape and move one of the heads to the cleaning po-
sition near the left tapered guide. See Fig. 4-1.
Fig. 4-1. Video head placed at the cleaning
position
CAUTION
NEVER TRY TO CLEAN THE HEADS WITH
THE MOTOR RUNNING
Saturate acleaning tip with SONY cleaning fluid
or methanol. (Spray cleaner, such as M/S-brand mag-
netic head cleaner, gives excellent results.) Rub the
cleaning tip across the head tip from side to side.
Avoid vertical motion, which might damage the video
head.
Clean the erase and audio/ control heads with
SONY cleaning fluid, if necessary. Move the cleaning
tip vertically across that part of the head surface that
normally contacts the tape.
Noisy slip rings cause intermittent dark horizontal
lines in the playback picture. To clean the slip rings,
remove the upper drum cover on the top of the
rotary-head drum assembly. Remove the tape from
the tape path. Apply afew drops of SONY cleaning
fluid to the slip rings. Turn on the motor for 10 to 20
seconds. Carefully wipe excess fluid from the tape
path around the rotary head drum assembly.
If slip-ring noise persists, clean the slip rings direct-
ly with ahead-cleaning tip saturated with SDNY
cleaning fluid. Rotate the head assembly by hand to
avoid contacting the brushes.
4-3. LUBRICATION
Five major lubrication points are:
1. Supply-Reel Table Bearing.
2. Take-Up Reel Table Bearing.
3. Capstan Bearing.
4. Take-Up Reel Idler Bearing.
5. Pinch Roller Bearing.
To lubricate the reel table bearings, remove the
screw and washer at the top of the spindle. Lift the
reel table slightly so that the hollow shaft of thetable
rises above the spindle. Apply one or two drops of
SONY oil, OL-1K, to the inner surface of th« reel
table shaft. Seat the reel table in its proper posrtion
and replace the screw and washers.
To lubricate the Capstan Bearing, pull up the
Capstan by hand, and apply afew drops of oil to» the
Oil Ring of the Capstan Bearing. See Fig. 4-2 ,Be
careful not to get oil on the surface of the Pinch
Roller. Wipe off excess oil.
Note: Capstan Bearing lubrication is important.
Oil as directed every 200 operating hours.
4- 1

Fig. 4-2. Lubrication of capstan bearing
To lubricate the Take-Up Reel Idler, remove the
Tape-Up Idler Cap. Apply adrop of oil to the shaft
of the idler. Wipe away excess oil from the rubber
driving surfaces.
Note: Alack of oil on this part sometimes
causes bearing noise in Play and Fast-
Forward modes.
To lubricate the Pinch Roller Bearing, remove the
pinch roller retainer. Apply afew drops of oil direct-
ly to the pinch roller oil ring.
Sliding Parts. All sliding parts of the tape-transport
mechanism are lubricated with grease which, in
normal use, need not be replenished. However, if new
parts are installed or lubrication is obviously needed,
apply ahigh-temperature grease at points of contact.
Avoid excessive lubrication.
4-4. DRIVE-BELT REPLACEMENT
Aworn or stretched drum drive belt results in
excessive slippage and loss of servo control.
Check the belt by inspecting the inner (bearing)
surface. Look for cracks and streaks along the long
dimension of the belt. Replace the belt if it is badly
scored along its length. To check belt length, remove
trie belt from the machine and compare its total
lexigth (flattened) with that of anew belt from
stock. Replace the belt if it is ^-inch or more longer
than anew belt.
To install the video-drum belt, stand the VTR on
its left side. Loop the belt over the motor pulley,
with the shiny side of the belt inside (against the
pulley). Grasp the bottom of the loop, turn it
one-half turn clockwise, and wrap around the pulley
of the rotary head drum assembly. See Fig. 4-3.
motor pulley
drum pulley
Fig. 4-3. Drive belt installation
4-5. DRIVE PULLEY ADJUSTMENT
The lower motor pulley requires adjustment if
the head-drum drive belt slips off the pulley or rides
against the upper or lower shoulder of the pulley. Ad-
just the pulley as follows. Remove the drive belt.
Loosen the set screw on the motor pulley and ad-
just its- height by eye until it is parallel to the pulley
on the rotary-head drum assembly. Reinstall the belt-
(See Section 4-4). Place the VTR in the normal hori-
zontal position. Thread and play the tape. Obserre
the position of the belt on the pulleys. Stop tke
machine and readjust pulley position to make tie
belt run in the center of the pulleys.
Check final pulley position by starting and stop-
ping the tape several times. Rewind the tape and ty
the fast-forward mode afew times. Make sure that
the belt does not drift towards the edge of the pulUy
or slip off when changing speeds.
4-2