Sony TC-765 User manual

GENERAL
Power Requirements:
Power Consumption:
AC Outlet:
Dimensions:
Weight:
Track:
Tape Speed:
SPECIFICATIONS
Fast Forward and
120V ac, GOHz (US, Canadian model} Rewind Time:
110V, 120V, 220V, 240V ac, 50/60 Hz
(UK, AEP, PX model)
110W (US, Canadian modei)
Q9OW (UK, AEP model)
80W (PX model)
Recording Time:
300W, unswitched (US, Canadian model) Heads:
Approx. 445 (w) x 525 (h) x 235 (d) mm
17 1/2 (w) x 205/ (h) x 91/4 (d) inches Motors:
including projecting parts and controls
26.5 kg, 58 !b 7 oz (US, Canadian model) Reel:
27 kg, 58 1b 8 oz (UK, AEP, PX model)
4-track 2-channel stereo recording and playback
19 cm/s (7% ips)
9.5cm/s (3% ips)
Approx. 150 seconds with 740 m (2,400 ft) tape
With 1,100 m (3,600 ft), 27cm reel
Stereo recording
180 minutes at 19cm/s
Mono recording
720 minutes at 9.5 cm/s
Record head 1, Playback head 1
Erase head 1
AC servo-controiled capstan motor 1
Induction reel motor 2
Up to 27cm (10%-inch)
— Continued on page 2 —
SERVICE MANUAL

TC-765
Frequency Response: With Sony Ferri-Chrome tape Equalization:
30—25,000 Hz + 3dB at 19 cm/s
30—18,000 Hz + 3dB at 9.5cm/s
With
SLH
tape
Inputs:
30—25,000 Hz + 3dB at 19 cm/s
30—18,000 Hz + 3dB at 9.5cm/s
With regular tape
30—18,000 Hz + 3dB at 19 cm/s
30—15,000 Hz + 3dB at 9.5cm/s
Wow and Flutter: NAB
0.04% WRMS at 19 cm/s
0.08%
WRMS
at
9.5
cm/s
Outputs:
DIN
40.07% at 19cm/s
+0.15% at 9.5cm/s
S/N Ratio: 61dB (NAB) with Sony Ferri-Chrome
Tape
61d8 (DIN 1975 rev.) with Sony
Ferri-Chrome Tape
56 dB (DIN, old)
Total Harmonic
Distortion: 0.7% Other Jack:
Bias Frequency: 160 kHz
MODEL IDENTIFICATION
Specification label
UK, AEP model US model
TAPECORDER TC-765
110.120.220.240V ~~ 50/60Hz 90W
MADE IN JAPAN
Canadian model PX model
TAPECORDER TC-765
AC 120V 60Hz HOW
MADE IN JAPAN
3,180uS + 50uS (19 cm/s)
3,180uS + 90uS (9.5 cm/s)
MIC (two phone jacks)
Sensitivity: 0.2mV (-72dB)
Impedance: for low-impedance microphone
LINE IN (two phono jacks)
Sensitivity: 0.06V (-22 dB)
Impedance: 100 kQ
REC/PB (connector) (UK, AEP, PX model)
Input impedance: less than 10k
LINE OUT (two phono jacks)
Normal level: 0.435V (-5 dB) with PB LEVEL
contro! set to center detent position
0.775V (OdB) with PB LEVEL
control set to ‘10’
Load impedance: 100k
Suitable load impedance: more than 10kQ
HEADPHONES (binaural jack)
Load impedance: for low-impedance headphones
REC/PB (connector) (UK, AEP, PX model)
Output impedance: Jess than 10kQ
11-pin remote control connector
0dB=0.775V
SON'Y.
TAPECORDER TC-765
AC
I20V 60 Hz HOW
MADE IN JAPAN
TAPECORDER TC-765
AC I20V 80W 50/60Hz

TC-765
SECTION 1
OUTLINE
1-1. BLOCK DIAGRAM — System Control Section —
o-—
(REC EQ SWITCHING)
eo
(REC AMP SWITCHING)
EMITTER
FOLLOWER
y 0732
SCHMIDT
SWITCHING SWITCHING FLIP FLOP TRIGGER ee (Fs) RV9O!
0732
073!
9730
0729,
728
aaa
0725,
724
Nx
“N
~~
TC-765
od $602
S602"! [TAPE SPEED
19cm —> 9.5em
S60l-|__—_ S60I-2
B+
STABILIZING
SUPPLY
Q704,705
0708~713
Bt
switcHine| _ | BoGENO!D
SUPPLY
a! 8707,708
OPERATES
IN FOR-
Sour SWITCHING
714, 715 ar7i6
SOLENOID
DRIVER
Q712, 713
SOLENOID
ORIVER
Q710 ,7il
| switcuine | D719
he 9709 re
|
$605 g
SHUT OFF
pay (SUPPLY)
(PB MUTING) ° LAMP DRIVER LAMP DRIVER 0760 _| SWITCHING
0718 9720 722
EMITTER
FOLLOWER
Q733
i
24V
|
me
he
REEL
SIZE
|
oh
V2?
|
TAPE
SPEED
ADJ
b | {Rvg0! 93cm
RV902 9.5¢em
|
all
!
RV702 ‘|
INVERSE 0744~747
TENSION
TORQUE
EMITTER
FOLLOWER
: SUPPLY REEL
MOTOR DRIVER
7 a
(FUNCTION BUTTON]
ea ms > Pl
ly <Ge<ee ee oe case. fl B+
STABILIZING
POWER SUPPLY
Q70t~ 703
Bt
24V ADJ
a «< 8 ?-
(C701 :
SYSTEM aes ,)
CONTROL \()~(@): 0U
0
ON OFF
(BIAS
OSC)
5603
(7)
b
®
(*)
D766
[TIMER]
7
Sees
Pera
(REC
MUTING)
aes
(AEP,
UK,PX
PORE
mamta
B+
werd
ae
D767
wooe)
_t
I
iS
SUPPLIED
WHEN
B+
‘
TAPE
REC
MODE
SWITCH
e@
(S103,S303)IS
ON.
L,
(LINE OUT
MUTING)
0765
SWITCHING
©
@
oT
i
748
©)
CO?’
cneoi
i
REMOTE
OFF
=
[ozes
EMITTER
ETIPEELOP:
ASTABLE
0764
O
O
$607
SWITCHING
FOLLOWER
sniteeine
Sa
MULTIVIBRATOR
O
C>/
IcontRo.
REC
a740
74!
a74a2
”
0746,
747
O
O O
MONITOR
MUTE
pa ey
D762
SONY-00527 / DRUCK 1
$602-2
Sem—> 9.5¢m
7 i/2
3 3/4
CAPSTAN
MOTOR
DRIVER
Q90I~903
D906~ 309
00009090000
PT60I

SONY-00527 / DRUCK 2

1-2. BLOCK DIAGRAM — Amplifier Section —
MIC_ATT (dB)
0
JO! Vo
rh 15
Ha pao 4
Mic AMP
Q!0!, 102
? LINE AMP
RVIO! Q103 ~ 105
| TC-765 TC-765 |
C135
REC BIAS A DJ
osc
. py] S103-4
nee
|
HRIOI
UNIT
ae
eal
7
>
PB
Qt
=
RFI40-2902
;
LI06
[REC]
REC BIAS TRAP. '
[mic]
MUTING REC -
aioe [REC MODE] !
US,CANADIAN
MODEL
REC
giog-3
HEE
MOD
$!03-!
— , =e LEVEL Lioe REC £0 ae F ees - [REC MODE]
LINE 09 = & xX EFI8-2902A2 } f$__ Bt
H si02~| Sey p avers 1 ERASE REC
aa 5 P NORMAL—> SPECIAL—>Fe ~Cr| yar H L107
f AEP, UK PX MODEL I ! | J O 9 | DUMMY VOLTAGE
RCH R-CH ? CONTROL
I 1 switcHinc] [switchinc] [switcHinc | |switchine | [SwiTcHING
L (EQ) (EQ) (EQ) (EQ) (EQ) $501
LINE
AMP
“fe
ve
Qulo
Qill
ail
Qits
aul4
dees
g
18+)
! Q126, 127 Si06 Rec/ Pe! LOW*-MED-"HIGH 9 ¥ 0 © ¥ ©
INPUT SELECT |
I
| iH) CN5O) |
| REC/PB l R-CH
SSS
SS
Se
ae
aS
Se
Se
s
TIO!
t SWITCHING | /2506_ON WHEN TAPE SPEED
HPIOI
RVIO4
p
HEADPHONE
AMP
ef}
950
0506
SWITCH
(S602)
TURNS
me se ae PB EQ AMP |PBLEVEL ADJ PB LINE AMP | sts l] iaeapeHONES 9.5m(3 3/4) MODE
QuS 17 ao Qi2t~ 123 3104 D
D103
MONITOR RVIO6 MEIO! Fy FROM
am) SOURCE METER ADJ STABILIZING | _POWER SUPPLY
GED
RVIOS
{
Osoie
Ge
OF
SYSTEM
CONTROL
f
:
[PB
LEVEL]
TAPE
CD
6
J303
z ee eee) ee > {LINE our
RY502 1@ H
MUTING 4 RY501 | Ca
gi20 : PRy503 |
|
SWITCHING SWITCHING ! I | -
9508 0507
Q507 ON: I !
Q508 ON WHEN TAPE SPEED WHEN REC MONITOR MUTE SWITCH(S607) TURNS OFF, |
SWITCH
(S602)
TURNS
OR
WHEN
REC
MONITOR
MUTE
SWITCH(S607)
TURNS
|
19cm (7 1/2) MODE ON AND MONITOR SWITCH(SI04) TURNS TAPE DIRECTION }
IN PLAYBACK MODE i Fr
!
|
———_-—-—)
Sees Ce [pS See ea ee ee ee Se 5
SWITCHING AEP, UK PX MODEL
|
9509
G
|
| |
| (Bean ON: WHEN ) |
| (MONITOR SWITCH(SI04) TURNS TAPE DIRECTION IN PLAYBACK: MODE
|
(eo ee a ed J
SONY-00527 / DRUCK 3

1-3.
NOTE ON REPAIRING
NOTE ON REPAIRING
1.
This set does not change playback level when
TAPE SELECT switches are changed.
The LINE OUT signal is cut when REC MONI-
TOR MUTE switch (S607) on the rear panel is
turned ON except when MONITOR switch is
in TAPE position in playback mode.
If TIMER switch is previously set to ON
position, it may happen to erase test tapes
because the set becomes automatically in the
auto playback (awakening) or auto record mode
determined by REC MODE switch position
when POWER switch is turned ON.
PB LEVEL controls on the front panel control
LINE OUT and HEADPHONES levels, and also
VU meters indicate the amount of PB LEVEL
controlling. When PB LEVEL is in the center-
click positions, LINE OUT levels are standard
0.44V (-5dB) and VU meters indicate ‘‘0”’.
When PB LEVEL controls are in their full-
clockwise stops, LINE OUT levels are 0.775V
(0 dB).
. Three kinds of hexagonal-socket screwdrivers
are needed for the following adjustment/
removal.
Screwdriver Adjustment/removal
Tension-arm pin
O + 1.27 Intermediate pin
ane Switch knob
Switch lever
Head azimuth
OT Ls FG-holding boss
ee Control knob
Motor pulley
SONY-00527 / DRUCK 4
| TC-765 1TC-765 |
Tape BIAS/EQ recommendations
The following list shows the recommended
settings, which have been determined through
critical listening tests and electrical character-
istic measurements on commercially available
tapes. The setting can be changed according to
the personal preference. For Sony tapes, be
sure to use the recommended settings to obtain
the optimum tape characteristics.
NORMAL SPECIAL
BASF LH, LHS SCOTCH #211,
SONY PR AGFA PE, PEM #212, #213
_|MEMOREX AMPEX 406, 407
SONY SLH SONY DUAD
SCOTCH CLASSIC |SCOTCH #206,
TDK AUDUA #207
MAXELL UD
SCOTCH #250
SCOTCH #218
SECTION 2
DISASSEMBLY
(to Mechanical Adjustment)
(to VU Meter and Variable Resistor Replacement)
(to Fuse Replacement)
(to Audio Amp Board Check)
(to Tape Speed and Forward Torque Adjustments)
(to B+ and Supply Reel Back Tension Adjustments)
(to System Control Board Checking)
Reel Panel Removal:
Amp Panel Removal:
Perforated Panel (top) Removal:
Perforated Panel (bottom) Removal:
Side Board (right) Removal:
Side Board (left) Removal:
Rear Board Removal:
>
0,90
8,0
0,9
0,0
®,®
®,®
©, ®
® ©
CS)
RK3x8
washer 12)
reel panel washer RK 3x8
reel panel
washer 0
reel sher
washer eel panel washe
reel panel washer 5)
RK3x8 f
°|
amp panel
perforated panel (top)
@ 84x10
ral
@ PS4xi0'
perforated panel
(bottom)
foot ass’y
rear board

SONY-00527 / DRUCK 5
TENSION ARM BASE REMOVAL
Microswitch Installation
Turn the tension lever and adjust
the position of the microswitch for
the specified clearance when
switches.
microswitch (S605)
tension lever
HEAD COVER REMOVAL
RK3x8
@ washer.
OPS3x6
@ tension arm
@ pinch roller -
® 83x8
@® lever caps
(Use hexagonal screwdriver.
OL 1.27 mm)
Note: When reattaching the pinch rollers,
be sure to reattach the one with
“1” mark at the right side.
@ tension roller cap
(Hold the guide roller ass’y
and remove the cap by
turning counterclockwise.)
E25
plastic washer (3mm dia.)
(4) tension roller ass‘y
@O kK2x5
@ spacer
@ tension arm
© B3x5
@Q tension arm base
@ vee! panel
RK3x8
washer }@
washer
© pinch roller screw
!
@ pinch roller cap
() plastic washer (4mm dia.}
!
pinch roller with “1” mark
'p tension arm
{E} head cover
| TC-765 TC-765 |
REEL TABLE REMOVAL
/
0 P3x8 —_¢ 49 table
MOTOR PULLEY INSTALLATION
Use a hexagonal screwdriver.
©) 1.5mm
motor pulley
brake solenoid holder
chassis
ELECTROSTATIC DISCHARGE BRUSH
INSTALLATION
0.5-0.8mm
drive belt
~ electrostatic disch arge
brush

SECTION 3
MECHANICAL ADJUSTMENT
3-1. MECHANICAL ADJUSTMENTS
Tape Path Adjustment
1. In playback mode, travel a blank tape SLH-S1,
and adjust the positions of the tension-arm
guide and intermediate pin.
adjustment screws (hexagonal socket)
tension arm
guide
guide roller intermediate pin
Tape should travel
in the center of
this width.
After the adjustment, tighten the adjustment
screws.
Travel a blank tape SLH7-740 and adjust the
position of the tape guides to eliminate tape
curls.
2.
0.025mm
tape guide
tape guide
Travel a blank tape SLH-S1 and adjust the
height of each head for the specified clearances.
To adjust the erase head height, select appro-
priate spacer.
To adjust the record and playback heads, turn
the height/zenith adjustment screws in the same
angle and direction.
height/zenith adjustment screws
After the adjustment, apply a suitable locking
compound to the adjusted screws.
SONY-00527 / DRUCK 6
Reel Table Height Adjustment
| TC-765 TC-765 |
— playback and rewind modes —
1.
Loosen the adjustment screws and adjust the
height of the reel tables for the specified height.
If the tape touches the reel in playback, fast
forward and rewind modes, recheck the tension
arms, standard reels and the tape.
Pinch Roller Lever Position Adjustment
Remove the head cover.
Reattach both the pinch rollers.
Place the set in the playback mode. Check that
the solenoid is in on condition (energized).
Loosen the adjustment screw and push the
slide adjustment plate in the arrowed direction
for the specified clearance between the pinch
roller levers A and B, and tighten the adjust-
ment screw.
After the adjustment, apply a suitable locking
compound to the adjustment screw.
Pinch roller lever B
pinch roller {right}
sliding adjustment plate
adjustment screw
Note: Adjustment screw positions for the 2T
PB and 4T PB heads are the same as the
2T REC head.
Azimuth adjustment screws are so con-
structed to react each other. Take care
in adjusting azimuth adjustment screw.
Tape should travel in the center of this width.
7" standard tape reels
height/zenith adjustment screws
5+0.5mm
(123/39)
reel tables
SC4x6
chassis
adjustment screws
(hexagonal socket}
angle adjustment
screws azimuth adjustment screws
Brake Adjustment (1) brake band shoe
adjustment screw brake band
Adjust both the supply- and take-up-side brakes.
brake solenoid brake band guide
In stop mode, 0.5—0.7mm clearance should
exist between the brake-band guide and brake
band.
In playback mode (the brake solenoid should
be in ON condition), loosen the adjustment
screw and adjust the position of the solenoid
link in the arrowed direction so that the brake
band and brake-band guide uniformely touch.
solenoid link @ In playback mode, the
brake band should
uniformely touch the
brake band guide at
brake drum here.
ge
brake band
0.5~0.7mm
(35/6q")
In playback mode, this
clearance should even.
Note: If the brake-release stroke is long, the
brake band may bend at the position
shown with *. Be sure not to bend the
brake band.
After the adjustment, apply a suitable locking
compound to the adjustment screw.
Brake Adjustment (2) and Brake Torque
Adjustment
Adjust both the supply- and take-up-side brakes.
In stop mode, loosen the adjustment screw
and adjust the position of the brake stopper for
the specified clearance between the brake
stopper and brake lever.
brake stopper
brake lever
After the adjustment, tighten the adjustment
screw and apply a suitable locking compound
to the screw. Adjust hooking
position.
Measure both the forward and backward brake
torques. Adjust spring-hook position for the
specified torques.
backward
1,800—2,500g-cm
(25-34 oz-inch)
600—700 g-cm
(8.5—9.5 oz-inch)
backward torque: adjustment screw
forward
brake arm
forward torque:
reel table

TC-765
Pinch Roller Pressure Check
— playback mode —
1. Place the dial-cord ring between the pinch
roller and pinch-roller cap.
pinch roller pinch-roller cap
t
dial cord (0.5mm dia.)
In playback mode, pull the spring scale on the
center line made by the centers of the capstan
and pinch roller.
3. Slowly return the pinch roller and read the
spring scale just when the pinch roller starts to
rotate.
i :
SF)
®
OOOO
ae = Senn eee
pinch roller
spring scale
800 g—1,200 g,
(1lb 120z—2 lb 10 0z) \
pressure difference Pull.
between the take-up
and supply sides:
within 200g (7 02)
Forward Torque Adjustment
; ; hub for measurement
Remove the side board (right).
Apply the rated ac voltage to the AC IN.
Set the TAPE SPEED switch to 19 cm/s and
REEL SIZE switch to 10%.
In playback mode, adjust RV703 for the
specified torques.
Set REEL SIZE switch to 7 and check torques.
2 Set the tension
REEL
SIZE
switch
arm
to
ON
position
using a rubber band
etc.
"
soz | 520-580g0m | 260-320 gem PRES Cees
(7.3-8.0 oz inch} | (3.6-4.4 oz inch}
380-440 g-cm 180—240 g-cm
(5.3-6.1 oz-inch} | (2.5—3.3 oz-inch}

TC-765 |
Supply Reel Back Tension Adjustment
Note: This adjustment requires a ultra-low
frequency audio signal generator. If the
signal generator is not available, do not
attempt this adjustment.
Remove the side board (left).
Apply the rated ac voltage to AC IN.
Set RV702 to the fully-counterclockwise stop.
Put a torque meter on the supply reel tape.
Unsolder the RED and WHT lead wires from
the FG at the system control board.
Set the signal generator’s frequency to 20.2 Hz
and attenuator to -20dB.
Connect the signal generator to the points from
where the two lead wires are unsoldered in
step 5.
Set REEL SIZE switch to 10% and TAPE
SPEED switch to 19 cm.
In playback mode, adjust RV702 for specified
torque.
Back tension torque
150 g:cm (2.1 oz inch)
120 g-cm (1.65 oz inch)
Change the audio signal generator’s frequency
to 7.14Hz and check the torque meter reeding.
Torque meter reeding
280-340 g-cm
(3.9—4.7 oz-inch)
220—280 g:cm
(3. 1—3.8 oz inch]
Fast Forward and Rewind Back Tesnion Check
Apply the rated ac voltage to AC IN.
Turn either the left- or right-side tension arm
on using a rubber band.
Put a torque meter on the supply reel table.
In fast forward mode, pull the torque meter in
the arrowed direction at a speed of 19—9.5 cm/s
and read the fast forward back tension on the
torque meter.
Put a torque meter on the take-up reel table.
In rewind mode, pull the torque meter and
read the rewind back tension as in step 3.
supply reel table take-up reel table
torque meter
Set the tension _
arm to ON position
using a rubber band.
e200 0000 o
REEL SIZE switch
sore
710-150 9-cm 80-120 g-:cm
(1.6-2.0 oz-inch) | (1.15-1.6 oz-inch)
70—110g-cm 50-90 9:cm
(1.0—1.5 ozinch}) | (0.7—1.2 oz inch}