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—

3-2. ELECTRICAL ADJUSTMENTS
5. After the’ adjust tS,
" _. pound.to the adjusted parts. Oe ae
Test Equipment/Tools Required:
audio oscillator (af osc)
VTVM
digital frequency counter
speed checker (SONY LFM-30)
attenuator (600 22)
¥%, W resistors, 600 2, 10 kQ, 100 k22
blank tape {
SONY test tapes:
J-9-F 1
J-19-F2
SPC-47
Standard Levels:
Input |
MIC
LINE IN
LINE OUT
Impedance
600 22
10 kQ2
Load Impedance
100 kQ2
pply locking «
SONY SLH-S1 (SPECIAL)
SONY NPS-1 (NORMAL)
Signal level
—60 dB (0.77 mV)
—10 dB (0.25 V)
Signal level
0 dB (0.775 V)
TC-388-4
Normal REC VOL Control Position:
REC VOL (MIC)
TAPE SPEED switch:
TAPE SELECT switch:
LINE OUT VOL control:
REC VOL (LINE):
FRONT MIC ATT switch:
PAN POT switch:
REC MODE buttons:
MONITOR switch:
19 cm/s
NORMAL
MAX
MIN
0 dB
OFF
pressed
TAPE
Mode: record and simultaneous playback
af osc
#) attenuator
blank tape
‘NPS-1
MIC --
LINE OUT
Turn REC VOL (MIC) control for 0 dB (0.775 V) VITVM
reading.
REC VOL (LINE)
TAPE SPEED switch:
TAPE SELECT switch:
LINE OUT VOL control:
REC VOL (MIC):
PAN POT switch:
REC MODE buttons:
MONITOR switch:
19 cm/s
NORMAL
MAX
MIN
OFF
pressed
TAPE
Mode: record and simultaneous playback
af osc
©
O
LINE IN
blank tape
NPS-1
LINE OUT
Turn REC VOL (LINE) control for 0 dB (0.775 V) VITVM
reading.
—15—

TC-388-4
Tape Path Adjustment and Head Height Rough 2. Tape Speed Adjustment
Adjustment
Settings:
TAPE SPEED switch: 19 cm/s
A) Tape Path Adjustment TAPE SELECT switch: NORMAL
LINE OUT VOL control: MAX
MONITOR switch: TAPE
. Adjust. tape guide (C) so that upper edge of the tape is PAN POT switch: OFF
aligned on upper edge of the erase head core. REC MODE buttons: released
Procedure:
. Loosen the set screw.
. Turn tape guide (C) 35° clockwise.
te ( Procedure:
. Fix the set screw.
Mode: playback
Head Rough Height Adjustments speed checker
Pere . SPC-47
. Adjust the screws indicated by * by turning alternately (4 kHz, 0 dB)
in the same direction so that upper edges of the erase,
record and the playback heads are aligned on the upper
edge of the tape.
. Turn the screws indicated by * 15° clockwise.
<4 acid cpaaenss OUT
SPC-47
(4
kHz,
0
dB)
digital
frequency
counter
tape guide (C)
set screw
‘0.025 mm 0.025 mm: tape guide
RH Hf
LINE OUT
lass
jams
Specification:
speed checker digital frequency counter
-1L.5~415% 3940 ~ 4060
If necessary, replace motor pulley.
Motor Pulley
Frequency
Part No.
3-518-068-61
3-518-068-51
3-518-068-41
3-518-068-01
3-518-068-11
3-518-068-21
3-518-068-31 slower

TC- 388-4
3. Playback Head Azimuth Adjustment 4. Record Head Height Adjustment
Settings: Settings:
TAPE SPEED switch: 19 cm/s TAPE SPEED switch: 19 cm/s
TAPE SELECT switch: NORMAL TAPE SELECT switch: SPECIAL
LINE OUT VOL control: MAX LINE OUT VOL control: MAX
MONITOR switch: TAPE PAN POT switch: OFF
PAN POT switch: OFF . REC MODE buttons: pressed
REC MODE buttons: released MONITOR switch: TAPE
REC VOL (LINE) control: normal position
Procedure: (See Page 15.)
Mode: playback
J-19-F2 Procedure:
3rd tone, 10 kHz
Mode: record and simultaneous playback
— j - f
pal blank tape
H-S1
LINE OUT C) 10 kQQ BEOY PES.
Adjust the azimuth adjusting screw for the highest VTVM fe) "1
reading. ati,
Adjustment Location:
k ,
R-CH (FRONT) LINE OUT
Adjust the three screws for the maximum R-CH (FRONT)
VTVM reading.
azimuth adjusting screw Adjustment Location:
Several peaks may appear, take the
highest.
. If the highest peak readings for all the
channels cannot be obtained at the
same screw position, take the mid be-
tween the both extreme positions of
the screws. At that time, ensure that
the difference between the maximum
and the minimum readings is not
more than 1 dB on the VTVM.
. If you turn the azimuth adjusting
screw more than one turn, perform
tape path adjustment (See Page 16).
. When touching the supply reel table
lightly, ensure that VTVM reading is
not increased more than 1 dB.
Zenith and azimuth
height adjusting adjusting
screws screw
Ba by ees

TC-388-4
5. Record Head Azimuth Adjustment
Settings:
TAPE SPEED switch:
TAPE SELECT switch:
LINE OUT VOL control:
PAN POT switch:
REC MODE buttons:
MONITOR switch:
REC VOL (LINE) control:
19 cm/s
SPECIAL
MAX
OFF
pressed
TAPE
normal position
6. Phasing Adjustment
Settings:
TAPE SPEED switch:
TAPE SELECT switch:
LINE OUT VOL control:
MONITOR switch:
PAN POT switch:
REC MODE buttons:
19 cm/s
NORMAL
MAX
TAPE
OFF
released
Procedure:
Mode: play back
(See Page 15.)
Procedure: J-19-F2
1st tone, 400 Hz
Mode: record and simultaneous playback 3rd tone, 10 kHz
R: LINE OUT 100 kQ
HEADPHONE 8 {2
af osc
O
blank tape
SONY SLH-S1
LINE OUT
HEADPHONE
1§ kHz, —30 dB (25mV) __
—_——
LINE OUT
Adjust the azimuth adjusting screw for the highest VTVM
reading.
Adjustment Location: ;
Check the following:
On the oscilloscope
in phase
2nd tone
(400 Hz)
3rd tone
(10 kHz)
in phase
: pT If necessary, finely adjust the playback head azimuth
azimuth adjusting screw adjusting screw. (See Page 17.)
Note: 1. If the highest peak reading for all the
channels cannot be obtained at the
same screw position, take the mid be-
tween the both extreme positions of
the screws and the difference between
each extreme peak level and the
adjusted output level should be within
1 dB difference. If the difference is
more than 1 dB, change the record
head.
. If you turn the azimuth adjusting
screw more than one turn, perform
record head height adjustment (See
Page 17).

TC-388-4
7. Playback Output Level Adjustment 8. Playback Equalizer Adjustment
Settings: Settings:
TAPE SPEED switch: 19 cm/s TAPE SPEED switch: 19 cm/s and 9.5 cm/s
TAPE SELECT switch: NORMAL TAPE SELECT switch: NORMAL
LINE OUT VOL control: MAX LINE OUT VOL control: MAX
MONITOR switch: TAPE MONITOR switch: TAPE
PAN POT switch: OFF PAN POT switch: OFF
REC MODE buttons: released REC MODE buttons: released
Procedure: Procedure:
Mode: playback 1. Mode: playback [TAPE SPEED switch: 19 cm/s (7% ips)]
J-19-F2
2nd tone (400 Hz) —10 dB
J-19-F2
Ist tone 400 Hz {0 dB)
—
LINE OUT
LINE OUT Make sure that VI VM reading is —10 dB (0.25 V).
. Mode: playback
J-19-F2
Adjust
R164,
264,
364,
464
for
0
dB
(0.775
V)
VIVM
3rd
tone
(10
kHz)
—10
dB
reading.
Adjustment Location: LINE OUT
Adjust the resistors R157, 257, 357, 457 for —10.5 dB
(0.23 V) VI'VM reading.
. Play back test tape J-19-F2 and ensure that each tone
output level deviation against 2nd tone is as follows.
. Frequency {Hz}
Level Deviation from eg “ast sft _2+1.5 dB) +2+2dB
2nd tone (400 Hz) 0.5 +1 dB| -0.5 £2 dB] -0.5 $1.5 dB | -2 41.5
. Play back test tape J-9-F1 and ensure that each tone
output level deviation against 3rd tone is as follows.
[TAPE SPEED switch: 9.5 cm/s (3% ips) ]
Level Deviation from
—1+2 dB} —-14#1. +0.5 £1,5 dB| +1.5 +2 dB
3rd tone (400 Hz) Lee siaeaotiae ees
Note: When this adjustment changes the play-
R164 R264 R364 R464 back level, readjust the play back level.
(L-CH) — (R-CH) (L-CH) — (R-CH)
— FRONT — — BACK —
| Adjustment Location:
*
R157 R257
{L-CH) (R-CH)
— FRONT —

TC-388-4
9. Level Meter Calibration 10. Trap Coil Adjustment
Settings: Settings:
TAPE SPEED switch: 19 cm/s TAPE SPEED switch: 19 cm/s
TAPE SELECT switch: NORMAL TAPE SELECT switch: NORMAL
LINE OUT VOL control: MAX LINE OUT VOL control: MAX
MONITOR
switch:
TAPE
PAN
POT
switch:
OFF
PAN POT switch: OFF REC MODE buttons: pressed
REC
MODE
buttons:
pressed
REC
VOL
(MIC):
MIN
|
REC VOL (LINE): normal position REC VOL (LINE): MIN
(See Page 15.)
Procedure: Procedure:
Mode: record Mode: record
REC MODE circuit board
|
“6
nC
Oil
if
Ss
(OV)
L608
my é
y : ae
>, 4
r
> 6
LINE OUT
1 kHz, —10 dB {0.25 V}
Adjust the resistors R174, 274, 374, 474 so that the pointer
of level meter is at 0 VU on the scale.
Adjustment Location:
Adjust the trap coils L605, 606, 607, 608 for minimum
VTVM reading.
Adjustment Location:
R174 R274 R374 R474
(L-CH) {R-CH) (L-CH) {R-CH)
|
= = = = L605 L606 L607 L608
mee ae (L-CH) (R-CH) (L-CH) (R-CHi
— FRONT — — BACK —

11. Record Bias Adjustment
Settings:
TAPE SPEED switch:
TAPE SELECT switch:
LINE OUT VOL control: MAX
MONITOR switch: TAPE
PAN POT switch: OFF
REC MODE buttons: pressed
REC VOL (LINE): normal position
(See Page 15.)
19 cm/s
SPECIAL
Procedure:
1. Mode: record and simultaneous playback
af osc
pi ane
‘oa KQ
peal
ore ollo00 0 Sk 000% 00° of j enit |
600 ea
LINE IN
1 kHz, -10dB8 ee Ww os
LINE OUT
Adjust the trimmer capacitors C609, 610, 611, 612 for
maximum VTVM reading.
. Turn the trimmer capacitor clockwise for 0.5 dB below
the maximum reading.
Adjustment Location:
C609 C610 C611 C612
(L-CH) (R-CH) (L-CH) [(R-CH)
— FRONT — — BACK —
| TC-388-4 TC-388-4 |
12. Record Level Adjustment 13. Record Equalizer Adjustment (SPECIAL)
Settings:
TAPE SPEED switch:
TAPE SELECT switch:
LINE OUT VOL control: MAX
MONITOR switch: TAPE
PAN POT switch: OFF
REC MODE buttons: pressed
REC VOL (LINE): normal position
(See Page 15.)
Settings:
19 cm/s and 9.5 cm/s
SPECIAL
19 cm/s and 9.5 cm/s
SPECIAL and NORMAL
TAPE SPEED switch:
TAPE SELECT switch:
LINE OUT VOL control: MAX
MONITOR switch: TAPE
PAN POT switch: OFF
REC MODE buttons: pressed
REC VOL (LINE): normal position
(See Page 15.)
Procedure:
Procedure:
1. Mode: record and simultaneous playback 1. Mode: record and simultaneous playback
[TAPE
SPEED
switch:
19
cm/s
(7%
ips)]
af
ose
oer ao
a kQ
acne
alld blank tape
S100 0% [oxe) 1,090!
“ KQ SES! ce
eee LINE IN
STTS000% [oxe) 1,000 6
se a VTVM
Ie,
“1008
(0.25
V)_
Leon
100
kQ2
[7]
100
k&2
OTe
OT
TLE
LINE OUT
VTVM
reading
Input
i ]
Signa level
Adjust
LINE OUT
—40 dB ~30dB
1 kH
2 | 7 mv) (25 mV)
—40 dB
(7.7 mV)
-30 dB
Adjust the resistors R123, 223, 323, 423 for 0 dB (0.775 V) (25 mV)
VTVM reading.
. Check the frequency response:
TAPE SPEED
Output Level Deviation
Signal
ae from 1 kHz signal
{input level
—40 dB, 7.7 mV)
SPECIAL
0 dB +1 dB
(0.69 ~ 0.87 V)
——|
«0dB+2dB
(0.62 ~ 0.97 V)
NORMAL
19 cm/s {7% ips) | 9.5 cm/s (3% ips)
* 0 dB +1dB
30 Hz +3 dB +3 dB
(0.69 ~ 0.87 V)
200 Hz +3 :dB +3 dB
«x 0dB+2dB 6 kHz +3dB +3dB
(0.62 ~ 0.97 V) 1 +3dB +3dB
9.5 cm/s
(3% ips)
+3 dB
+3dB
* check only
Adjustment Location:
Note: If necessary, readjust the record bias
adjustment (See Page 21).
Adjustment Location:
R323 R423
(L-CH) (R-CH)
— BACK —
R123 R223
(L-CH]) (R-CH)
— FRONT —
L303 L403
{L-CH) (R-CH)
— BACK —
L103 L203
{L-CH) (R-CH)}
— FRONT —
14. Record Equalizer Adjustment (NORMAL)
Settings:
TAPE SPEED switch: 19 cm/s and 9.5 cm/s
TAPE SELECT switch: NORMAL
LINE OUT VOL control: MAX
MONITOR switch: TAPE
PAN POT switch: OFF
REC MODE buttons: pressed
REC VOL (LINE): normal position
(See Page 15.)
Procedure:
1. Mode: record and simultaneous playback
. ose
blank tape
a Pra) NPS-1
ae
ol, SHe00 0% 000% e) of
600 |
LINE IN
LINE OUT
‘ input ss VTVM
Signal level Adjust reading
-40 dB —30 dB
acu i Cee Te (25 mV)
L102
—40 dB 202 -30 dB
(7.7 mV) 302 (25 mV)
402
2. Check the frequency response:
Output Levet Deviation
from 1 kHz signal
9.5 cm/s (3% ips)
+3 4B
+3 dB
Signal
{input fevel
—40 dB, 7.7 mV}
| 19 cm/s (7% ips)
30 Hz | +3 dB
200 Hz +3 dB
6 kHz +3 dB +3 4B
I 10 kHz +3aB
15 kHz +3 4B
20 kHz
23 kHz |
Note: If necessary, readjust the record bias
adjustment (See Page 21).
Adjustment Location:
£202
(R-CH)
— FRONT —
L102
{L-CH)
= 22:—

-4 1C-388-4 |
13. Record Equalizer Adjustment (SPECIAL)
Settings:
TAPE SPEED switch: 19 cm/s and 9.5 cm/s
TAPE SELECT switch: SPECIAL
LINE OUT VOL control: MAX
MONITOR switch: TAPE
PAN POT switch: OFF
REC MODE buttons: pressed
REC VOL (LINE): normal position
(See Fage 15.)
Procedure:
1. Mode: record and simultaneous playback
af osc
pipe ras
10 a
——
ore ! 1.000% oo” 1,099
600 ba
LINE IN
pe LINE OUT
Input Adjust VTVM
levet reading
Pane
-40 dB —30 dB
1 kH st
7 | (1.7 mv) (25 mV)
—40 dB -30 dB
(7.7 mV) (25 mV)
2. Check the frequency response:
Output Level Deviation
i 4
Signal from 1 kHz signal
{input level
—40 dB, 7.7 mV)
19 cm/s (7% ips) | 9.5 cm/s (3% ips)
30 Hz +3 dB
Note: If necessary, readjust the record bias
adjustment (See Page 21).
Adjustment Location:
L103 1.203 | 1303
(L-CH) (R-CH) (L-CH) (R-CH)
— FRONT —
— BACK —
Record Equalizer. Adjustment (NORMAL)
Settings:
TAPE SPEED switch:
TAPE SELECT switch:
LINE OUT VOL control:
MONITOR switch:
PAN POT switch:
REC MODE buttons:
REC VOL (LINE):
Procedure:
af ose
19 cm/s and 9.5 cm/s
NORMAL
MAX
TAPE
OFF
pressed
- normal position
(See Page 15.)
co kQ,
+
ore olo00 OI 000% one) el
600 =
LINE iN
. Mode: record and simultaneous playback
blank tape
NPS-1
=I
LINE OUT
. Input <
Signal level Adjust reading
~40 dB —30 dB
kHz (7.7mV) fo (25 mV)
L102
--40 dB 202 -30 dB
antes (7.7 mV) 302 (25 mV)
402
. Check the frequency response:
Signal
linput level
Output Level Deviation
from 1 kHz signal
—40 dB, 7.7 mv)
19 cm/s (7% ips) | 9.5 cm/s (3% ips)
ie
30 Hz +3 dB
200 Hz
+3 dB
+3 dB
+3 dB
+3 dB
3d
B
+3d
B
Note: If necessary, readjust the record bias
adjustment (See Page 21).
Adjustment Location:
L302
15. Dummy Coil Adjustment
Settings:
TAPE SPEED switch: 19 cm/s ,
TAPE SELECT switch: SPECIAL
LINE OUT VOL control: MAX
MONITOR switch: TAPE
PAN POT switch: OFF
REC MODE buttons: pressed
Procedure:
1. Mode: record
digital frequency
counter
Memorize the counter reading.
Release REC MODE Adjust the Coils so that the
buttons of the following | trequency is the same as step 1
channels.
FRONT L-CH
FRONT RCH ©
BACK L-CH
BACK R-CH
2. (1) Mode: 4-channel record and simultaneous playback
(2) Mode: 2-channel record and simultaneous playback
(3) Mode: 1-channel record and simultaneous playback
af osc
blank tape
‘aa kQ SLH-St
—a,
TP O00 FF (oxe) 1,000 of
600 a
LINE IN
1 kHz, —40 dB (7.7 mV)
20 kHz, —40 dB (7.7 mV) Loess
VTVM
100 kQ
OTHE:
LINE Oe
Make sure of the following:
Record and simultaneous fe] levet
playback utput feve
4-channel [ 0.dB (0.775 V)
2-channel | 0 +2 4B (0.62 ~0.97 V)
1-channel 0 +2 dB (0.62 ~ 0.97 V)
Adjustment Location:
— FRONT - — BACK —
(L-CH) (R-CH){L-CH) (R-CH)
L601 L602 L603 L604
16. Trap Coil (Bias Leakage) Adjustment
Settings:
TAPE SPEED switch:
TAPE SELECT switch:
LINE OUT VOL control:
PAN POT switch:
REC MODE buttons:
REC VOL (LINE):
MONITOR switch:
Procedure:
19 cm/s
NORMAL
MAX
OFF
pressed (FRONT buttons
or BACK buttons)
normal position (See Page 15.)
SOURCE
1. (1) Mode: 2-channel record (FRONT L-, R-CH)
(2) Mode: 2-channel record (BACK __L-, R-CH)
VTVM
100 kQ. ical
unit tC
LINE OUT
FRONT L-, R-CH L151, 251
minimum
BACK _ L-, R-CH L351, 451
2. Make sure of the following:
Record
VTVM reading
4-channel
l-channel
Less than —40 dB (7.7 mV)
Adjustment Location:
L351 £451
{L-CH) {R-CH)
— BACK —
TC-388-4
{
H
I
:
t
H

SECTION 4
DIAGRAMS
TC-388-4
| TC-388-4 #TC-
4-1.
SCHEMATIC
DIAGRAM
FRONT
RECORD
AMP
CIRCUIT
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7
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2908
RECORD LAMP
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TC-388-4 TC-388-4
FRONT RECORD AMP
FRONT PLAYBACK AMP CIRCUIT BOARD _ 7 : CIRCUIT BOARD
MONITOR CIRCUIT BOARD | ICIS! TA—7122A QISI 25C634A —Q152 2SC634A IcI52 TA-7I22AP —QIS3 2SC634A
SOURCE-<+eTAPE S)
LINE OUT
S2-1
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PB
TRAP
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C53 RIS
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PP138-4204 (1) Ct57
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(Reference numbers start from 251.) ACIRCUIT BOARD
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BACK PLAYBACK AMP |CIRCUIT BOARD | _ 7 , Tk
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All
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and
capacitors
are
in
{2
and
LF
unless
< Y po te) —————— otherwise specified.
Hl
@ Ket +4 a STOP FF, REW (A) @ Letter in { ) suffixed to variable resistor value
@- aa ? a 23 FWD | indicates characteristics.
(9) 8 24 a a3 24 re 0 ate e mr : Chassis ground
1 SS
(0) L 26 - 26> X26 @ Vatues for transformer windings are DC resistance.
f 7 7
15 | 6 -—___—_—_——_“4 14> | _ 14> 4 T a 71 @ (N): Low noise resistor
; |____¢a2)
7 1 O00 | ee y @ Voltage values shown are measured with a VOM
ee | tt eis 18 24 26 22 | 23 vv vsri METER LAMP [ ° \ (DC 20 kQ/V, AC 8 k22/V} and VTVM. Variations
a 7 £13) TAPE SPEED SWITCH CIRCUIT BOARD SPEICIAL~** NORMAL “PLY PL2 PLZ PL4 I rn 1C-624H1 ray be noted due to normal production tolerances.
15
-
£ 2
7
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playback
mode
voltage
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\7 4 es = 080! ; d s72 (0) g G c | | { }: record mode voltage (VT VM}
| a
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$8
PAUSE
MUTING
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35
|
|
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|
AC
[sv] R802 > B03 Jgcme—e-o-9,5°%s 5.6V | I Ref. No. Switch
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BIAS ADJ C80. . o ie p903 D901 1 3 record/playbac playback
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TTT TT 4.701720) k
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23 23" | cgoy 6902 |cao3I 904, [50V pone s8 PAUSE MUTING OFF
BIAS AD 1000 220 +1000L_--.G-t “47 SIBOI-O2 s9 MUTING OFF
C2
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35V
35V
7
35V
50V
$10
POWER
OFF
14
>—______
14
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7
$11
motor
shut-off
OFF
: F | VOLTAGE SELECTOR $12 bias timing OFF
“ POWER SUPPLY CIRCUIT BOARD 1\Gow 20] | $101, 201, 203
14 Sar” §301, 401, 303 | REC MODE playback
PO)
0 —— ind Oo $102, 103, 202
I So, 5303, 402, 403 | REC MODE playback
v 1S |
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|
|
C702
|
|
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|
|
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OR — 26 —