Sony TC-388-4 User manual

Power Requirements:
Power Consumption:
Tape Speed:
Recording Time:
Reels:
Recording System:
Frequency Response:
Distortion:
SPECIFICATIONS
120V AC, 60 Hz (USA Model)
120V AC, 60 Hz (100, 110, 127,
220, 240 V AC, 50 Hz adjustable
by the Sony personnel) (PX Model)
40 W (USA Model)
32 W (PX Model)
19 cm/s (7/2 ips), 9.5 cm/s (3% ips)
45 min. at 19 cm/s (7 ips)
quadraphonic recording with 1,800
ft tape
17.8 cm (7 inches) or smaller
4-track quadraphonic, stereo and
mono system
With Sony SLH tape
20 ~ 30,000 Hz at 19 cm/s (7/2 ips)
20 ~ 23,000 Hz (+3 dB) at 19 cm/s
(7/2 ips)
30 ~ 19,000 Hz at 9.5 cm/s (3% ips)
With standard tape
20 ~ 25,000 Hz at 19 cm/s (7'/2 ips}
30 ~ 17,000 Hz at 9.5 cm/s (3% ips)
1.2%
Wow and Flutter:
S/N Ratio:
Inputs:
Outputs:
Dimentions:
Weight:
0.09 % at 19 cm/s (7 ips)
0.12% at 9.5 cm/s (35/4 ips)
55 dB with Sony SLH tape
Microphone inputs ...........: 4
Sensitivity 0.2 mV (—72 dB)
Accept low impedance microphones
Line inputs 2.0... eee 40
Sensitivity 0.06 V (—22 dB)
Impedance 100 kQ
Line OUTPUTS .......... eee 4
Output level 0.775 V (0 dB) at load
impedance 100 KQ with line output
volume control set to MAX
Suitable load impedance higher than
10kQ2
Headphone outputs........... 2
Accept an 822 stereo headphones
422 (w) x 505 (h) x 220 (d) mm
16°78 (w) x 197 (h) x 87/4 (d) inches
14.5 kg (31 Ib 14 oz)
SERVICE MANUAL

TC-388-4 |
TABLE OF CONTENTS
Section Title Page
DPE Cihicationst<s we Be seesaw 2s Oa, eR eh oe eta ee tat Il
7. OUTLINE
1-1. PAN POT (Panoramic Potentiometer)................. 3
1-2. MUTING/PAUSE Lever .... 2.20.00... 2 ee ee ee ee 3
1-3. Block Diagram ...... 2... 2... ee 3
1-4. External View . 2... 2. 2 ee 4
le5.°. Internal’ Views: #08 3: a ke Oa) AS ee hs ple ee ee ed 4
2. DISASSEMBLY ¢.4- sc6 0006 wee ee ee ee a ee Se 8
3. ADJUSTMENTS
3-1. Mechanical Adjustments .... 2.2.2.2... 00000 eee eee 9
3-2. Electrical Adjustments... 2... 0... ee 15
4. DIAGRAMS
4-1. Schematic Diagram... ... 2... 2... 0... ee ee 24
4-2. Mounting Diagrams. ...........0 0.2.00 2 eee eee eee 27
4-3... Level. Diagrams: 3. .30200cn ee A a a ee PS 33
5. PACKING AND EXPLODED VIEWS ................... 34
6. ELECTRICAL PARTS LIST ............-2....0-02004. 45
7. HARDWARE! :. 5: ares alg ae be eed hk ee Geral & Db ek ere 50

TC-388-4
SECTION 1
OUTLINE
1-1. PAN POT (Panoramic Potentiometer)
With PAN POT switch turned ON, the BACK
channels are mixed into the FRONT channels to
reproduce the two-channel stereo sounds and PAN
POT controls can shift a sound image on a reproduced
stereo sound field. The two FRONT channels are used
for reproducing astereo sound field and the two BACK
channels for reproducing a sound image and shifting it.
r- FL EK annn ——
REC/VOL MIC ioe
MAIN
VOL C402
1-3. BLOCK DIAGRAM
“REC FRONT L-CH —————————
J5-1
LINE
IN
PAN POT SW
ON, S3
— REC FRONT R-CH —~
*—_— FEC BACK CH ——+
|S af
MIC
10302
153 Q—---
NE IN? 7 PB FRONT L-CH ——______.,
S2| MONITOR
PB LEVEL
LINE OUT
Val
1-2. MUTING/PAUSE LEVER
With MUTING/PAUSE lever depressed halfway,
the tape transport is not in pause mode but the record
signals are muted. With the lever farther depressed
and locked, the tape transport is in pause mode.
With the lever depressed halfway, S8 is turned ON
and the base of Q801 is positive-biased, Q801 turns
ON and applies B+ voltage to each base of Q101,
Q201, Q301 and Q401 to mute each channel record
signal. The rise time of muting is 0.1 seconds, which
is determined by the time until C802 is charged up to
1.2 volts through R802. With the lever released, S8 is
turned OFF and C802 discharges. The decay time of
muting is 0.6 seconds, which is determined by the
time until the voltage across C802 decreases into
1.2 volts.
RECORD ;
LEVEL
L = RH
Osc § 5
0701, a702 ~~ EH
0901. TI{PT)
D902
$10
—_— POWER
2 oS AC IN
|
ss |
l
re | (C624H1
Oo
oA
‘ . HEADPHONE
J6-1
©) LINE OUT
Ref. No. Switch Mode
$2 MONITOR TAPE
83 PAN POT OFF
S4 MIC ATT 0 dB
$8 PAUSE MUTING OFF

TC-388-4
1-4. EXTERNAL VIEW
3-472-264-00
3-536-258-00
Knob,
TAPE
SPEED
Support,
head
cover
1-578-152-47
Lamp, pause muting (PL10) X-3536-208-2
3-472-263-00
Knob
Ass’y,
FF/FWD/REW
Knob, MUTING/PAUSE
X-3518-012-0 X-3536-209-2
Cover Ass’y, head
Button Ass’y, REC
1-514-817-41 (PX Model)
1-516-023-11 (USA Model}
1-514-448-00
Switch,
slide;
HEADPHONE
(S5)
Switch,
slide;
POWER
(S10)
1-516-447-00 1-516-024-00
Switch,
lever
slide;
TAPE
——_
Switch,
slide;
PAN
POT
{S3)}
SELECT ($7)
Eadingts aa 1-516-446-00
WELEO WeVeT NOE) Switch, lever: MONITOR (S2)
FRONT MIC ATT (S4)
1-5. INTERNAL VIEWS
1-506-3 12-00
Connector, joint terminal (CNP1}
1-507-323-00
Connector, joint terminal (CNJ1}
X-3536-216-1
Complete Circuit Board,
X-3536-220-1 TAPE SPEED switch
Complete Circuit Board,
power supply
Integrated Circuit, BX-252
{C901}
X-3536-222-1
Complete Circuit Board, bias osc

TC-388-4
X-3536-218-1 X-3536-214-1
Complete Circuit Board, MIC jack Complete Circuit Board, MONITOR
X-3536-217-1
Complete Circuit Board,
PAN POT switch
X-3536-215-1
Complete Circuit Board,
pan pot
X-3536-227-1
Complete Circuit Board,
REC MODE
X-3536-226-1
Complete
Circuit
Board,
:
front
record
X-3536-225-1
Complete Circuit Board,
back record
X-3536-223-1 : X-3536-224-1
Complete Circuit Board, front playback Complete Circuit Board, back playback
3-518-069-00
Belt, motor pulley 3-472-332-00
Beit, take-up
1-520-1 79-00
Meter, level (ME1 ~4)

'C-388-4
8-825-527-00 8-824-729-40 8-829-342-40
Head, erase Head, record Head, playback
EF137-2904H RP138-2904 PP138-4204

TC-388-4 TC-388-4
|
SECTION
2
DISASSEMBLY
2-1. AMP PANEL REMOVAL
Remove four screws indicated by e@.
AB3x 16 AB3x 1h
2-2. REEL PANEL REMOVAL
1) Remove two screws indicated by * and remove
X-3536-201-0
head
cover.
Lever
Ass’y,
pause
MUTING/
PAUSE
knob
2)
Remove
two
head
cover
supports.
1-514-697-00
[
head
cover
support]
ta
7
3)
Remove
MUTING/PAUSE
knob
by
turning
it
Switch,
leaf;
PAUSE
AB3x
12
:
AB3x
12
counterclock
wise.
MU
:
:
Sena
nNGIee
@RK3x6
@RK
3x
12
4)
Remove
five
screws
indicated
by
4.
@RK
3x
12
@
RK
3x
12
2-3. CABINET REMOVAL
Remove eight screws.
1-514-039-12
Switch, micro; motor shut-off (S11)
cabinet
PS4x 14 | Ps
j; oo ©@&
sax 14

SECTION 3
ADJUSTMENTS
3-1. MECHANICAL ADJUSTMENTS
Tension Arm (A) Adjustment
— playback mode —
Perform this adjustment after turning supply reel
table counterclockwise by hand.
supply reel table
Adjust by turning
the
screw.
—
tension
arm
pin
tape guide (C)
tension arm (A)
locus drawn
: ; be se
by thepin 7.5 ~8.5mm pte
Movement Che re)
Note: Ensure that the tape uniformly comes in
contact with the tension arm pin at the
beginning and end of the tape. (If
necessary, adjust by bending tension arm
pin.)
tension arm pin
tape
tension arm (A)
TC-388-4
Capstan Idler Adjustment
Perform this adjustment after motor pulley height
check (See Page 12).
— playback mode —
motor pulley — es BE
‘to.be-flush 9.5 embs (34a ips)
m/s
1 To be some clearance.
(7/2 ips)
capstan idler
Adjust the height of
the jdler.by loosening.
the screw. ca
Note: 1. Perform this adjustment for both
vertical and horizontal positions.
2. After the adjustment, apply locking
compound to the screw.
3. Make sure that capstan idler does not
contact motor pulley and flywheel in
stop mode.
TC-388-4
Pause Mechanism Adjustment
— playback mode —
@) With pause lever pulled, adjust pause adjusting plate
position by loosening screw (A) so that clearance
between pinch roller and capstan is 0.5 ~ 1 mm (1/32).
Take-up Torque Adjustment
— playback mode at 9.5 cm/s (3% ips) tape speed —
Take-up torque
decrease MO" increase
S
Pause rod
plate
tension arm (A)
Pause lever
Note: 1. When pulling pause lever in stop
mode, ensure that pause lever is not
locked.
2. When pulling pause lever in playback
mode, ensure that brake operates.
pause adjusting
Spring
Scale
Note: After the adjustment, apply locking
compound to the screw.
Tension Arm (A) Back-tension Adjustment
Perform this adjustment after tension arm (A)
adjustment (See Page 9).
: Use a7’ reel tape. ae : cee ie
- playback mode: 45~ 58g 2°.
whe OS LEO LOL OR)?
fast forward mode: 18 ~ 21g 0°
supply reel
© (0.53. ~0.71 02)
spring
beginning
; Adjus t by changing tha- tension arm pin
hook position-of spring.
Note: lf the specified back tension is not
obtained by the spring hook positioning,
perform tension arm (A) adjustment
(See Page 9).
2A =

TC-388-4 T1C-388-4
Fast Forward Pulley and Driving idler Adjustment
— stop mode —
Reel Table Height Adjustment
— playback, rewind and fast forward mode —
Bias Timing Switch (S12) Position Adjustment
supply reel
table
fast forward pulley
driving idler
take-up
hs C2 ree/
-to.be flush
25.1 mm (1")
35mm.
(14s os) stop mode
idler am
F— -Loosen-the screws and,
adjust microswitch | =
bracket position. .°:.
If necessary, adjust by bending idler arm.
(S12)
‘Adjust by changing the washer
"$0 that the tape does not come |
’ in.contact with the flange of
microswitch bracket
the reel... Note: Ensure the following:
1. Bias timing switch is actuated in
Washer
playback
mode.
2. When changing the mode from record
to stop slowly, REC button is released
after the bias timing switch is released.
Part No.
3-701-443-01
Thickness (mm)
0.13
0.25
0.50
3-701-443-11
3-701-44 3-21
Motor Pulley Height Check
Note: After the adjustment, perform back
tension and take-up torque adjustments.
(See Page 10).
motor pulley
Brake Torque Adjustment (supply reel table)
— stop mode —
750 ~ 250 9- cm
(2.1 ~ 3.5 oz- inch)
teats
1,300
~
1,700
g-
cm
direction
D
|
(18
~
24
oz:
inch)
supply reel direction C
table braking
torque
7 mm { Yea")
Adjustable for direction D only.
Idler Arm Stroke Check
— playback mode at 9.5 cm/s (3% ips) tape speed —
Fast Forward and Rewind Torque Adjustments
— rewind and fast forward mode —
Adjust by positioning fast forward idler
limiter Spring 0%.
O
supply reel
table
0.3 ~0.5 mm Yan")
Adjust by bending.
Adj ust by changing
‘hooking position: -
Of spring.
Note: The torque should be measured just
when driving idler stops rotating.
—11-
2249
=
Brake Adjustment (take-up reel table)
1. Brake Shoe Adjustment
— rewind mode —
take-up reel
table
‘Adjust by turning
‘this. screw.
2. Brake Torque Adjustment
— stop mode —
350 ~ 450 g- cm
(4.9 ~ 6.2 oz: inch)
1,300 ~ 1,700 g- cm
(18 ~ 24 oz: inch)
direction B
take-up ree!
table braking
torque
direction A
brake lever (A)
Adjust by. bending
this portion.
take-up reel
table
strong
“strong.
L- (Cut one turn of.
| “the spring off.)
ldirection A}
lever weak oo"
“(Bend the tab:

TC-388-4
Pinch Roller Stroke Adjustment
Remove head deck by removing four screws indicated
by Aon Page 41.
— stop mode —
eo he screw and adjust
faint: lever Position. er
Fix the: screw While pushing ©
< “joint lever as shown by. arrow. :
retractive lever
Joint lever
washer
fs
pinch roller shaft
1 at
3~4mm (Ys ~ 432")
retractive lever
head deck — bottom view —
Note: 1. Put dummy capstan * into capstan
bearing and ensure that pinch roller
shaft moves by 3~4 mm(4 ~ 32”)
on the retractive lever when changing
the mode from stop to playback.
2. Ensure that washer of pinch roller
shaft does not contact the part
indicated by * when changing the
mode from playback to fast forward
slowly.
3. Apply locking compound to the
screw,
* Dummy Capstan (capstan shaft)
Prepare a flywheel ass’y (X-3472-003-0) and
remove capstan shaft from it by patting the
head of the capstan shaft with the hammer,
taking care not to bend the shaft.
Bottom view of head deck
~13-—
TC-388-4
Pinch Roller Pressure Check
1. Put dummy capstan > into capstan bearing and 2. Measure the pressure.
ensure the following. — playback mode —
— playback mode —
pinch roller lever (B) Pinch roller
dummy capstan
pinch roller lever (A)
head deck — bottom view —
retractive lever
Note: The pressure should be measured just
when the pinch roller releases from
capstan.
% Dummy capstan (capstan shaft)
Prepare a flywheel ass’y (X-3472-003-0) and
remove capstan shaft from it by patting the
head of the capstan shaft with the hammer,
taking care not to bend the shaft.
Shut-off Mechanism Adjustment
— stop mode —
head deck
(bottom view)
shut-off lever (H)
© Fath mm 433" ye
ae With: shut-off niaehaniarn:
shut-off lever
bracket
shut-off mechanism
release
Note: After the adjustment, apply locking
compound to the screws.
—~14—