Sony TC-K370 User manual

TC-K370/RX370
SERVICE MANUAL
AEP Model
UK Model
Australian Model
TC-K370
US Model
Canadian Model
AEP Model
TC-RX370
Photo: TC-K370
* Dolby noise reduction and HX Pro headroom extension manufactured
under license from Dolby Laboratories Licensing Corporation. HX Pro
originated by Bang & Olufsen.
“DOLBY”, the double-D symbol OO and “HX PRO” are trademarks of Dolby
Laboratories Licensing Corporation.
Model Name Using TC-W370/W41 1
Similar Mechanism /WR511/WR570
TC-K370 | TCM-190VB12C
TC-RX370 | TCM-190RB12C
SPECIFICATIONS Tape Transport
Mechanism Type
4-track 2-channel stereo
Approx. 90 sec. (with Sony C-60
Recording system
Fast-winding time
Outputs
Line outputs Rated output level] 0.32 V ata load
cassette)
(phono
jacks)
impedance
of
Bias
AC
bias
47
k
ohms
Motors
Capstan
motor
x
1
(DC
motor)
Load impedance | Over 10 k ohms
Headphones 0.3 mW at a load
(stereo phone impedance of
jack) 32 ohms
Reel motor x 1 (DC motor)
Signal-to-noise ratio (at peak level)
Dolby NR switch OFF B-Type | C-Type
Cassette ON ON
Output level
General
Type | (Sony HF-S)
| Type lV (Sony METAL-SLT) | 58dB | 66dB | 73dB
Type |! (Sony UX-S) 57dB | 65dB
5a | oae | 7008.
Total harmonic distortion
1% (with Sony METAL-SLT cassette)
Frequency response (DOLBY NR OFF)
Type IV cassette
(Sony METAL-SLT)
| (Sony HF-S)
Wow and flutter
Inputs
recording]
Type Il cassette
30 - 15,000 Hz (+3 dB, IEC)
(Sony UX-S)
Type | cassette 30 - 14,000 Hz (+3 dB, IEC)
30 - 15,000 Hz (+3 dB, IEC)
30 - 13,000 Hz [+3 dB, OVU (-4 dB)
socal
40.13% W. Peak (IEC)
0.07% WRMS (NAB)
+0.18% W. Peak (DIN)
_ Line inputs
(phono jacks)
77.5 mV
input impedance | 47 k ohms
Sensitivity
Power requirements
Power consumption
Dimensions
Weight
US, Canadian model :120V AC, 60Hz
AEP, Germany, Australian model:
220-230V AC, (or 240V AC adjustable
by Sony personnel) 50 /60Hz
UK model :240V ‘AC, (or 220V AC adjustable
by Sony personnel) 50/60Hz
20 W
Approx. 430 x 123 x 287 mm (w/h/d)
(17 x 4% x 113% inches)
including projecting parts and controls
Approx. 3.9 kg (8 Ibs 10 02)
Supplied accessory Audio connecting cords (2)
Design and specifications subject to change without notice.
STEREO CASSETTE DECK
ONY.

TC-
K370/RX370
SAFETY CHECK-OUT
After correcting the original service problem,
perform the following safety check before releasing
the set to the customer:
Check the antenna terminals, metal trim, ‘“‘metallized”’
knobs, screws, and all other exposed metal parts for
AC leakage. Check leakage as described below.
LEAKAGE TEST
The AC leakage from any exposed metal part to
earth ground and from all exposed metal parts to any
exposed metal part having a return to chassis, must
not exceed 0.5 mA (500 microampers). Leakage
current can be measured by any one of three
methods.
Ls
A commercial leakage tester, such as the
Simpson 229 or RCA WT-S540A. Follow the
manufacturers’ instructions to use these instru-
ments.
A battery-operated AC milliammeter. The Data
Precision 245 digital multimeter is suitable for
this job.
Measuring the voltage drop across a resistor by
means of a VOM or battery-operated AC volt-
meter. The “limit”? indication is 0.75 V, so
analog meters must have an accurate low-
voltage scale. The Simpson 250 and Sanwa
SH-63Trd are examples of a passive VOM that
is suitable. Nearly all battery operated digital
multimeters that have a 2 V AC range are
suitable. (See Fig. A)
To Exposed Metal
Parts on Set
AC
vo/tmeter
(0.75 V)
= Earth Ground
Fig. A. Using an AC voltmeter to check AC leakage.
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY MARK A OR DOTTED
LINE WITH MARK A ON THE SCHEMATIC DIAGRAMS
AND IN THE PARTS LIST ARE CRITICAL TO SAFE
OPERATION. REPLACE THESE COMPONENTS WITH
SONY PARTS WHOSE PART NUMBERS APPEAR AS
SHOWN IN THIS MANUAL OR IN SUPPLEMENTS PUB-
LISHED BY SONY.
TABLE OF CONTENTS
Sectton Title
SECTION
1.
GENERAL:
-
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SECTION:
2.
DISASSENBEY@
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Bis
SECTION
3.
ADJUSTMENTS:
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2
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SECTION 4. DIAGRAMS
4-1].
Circuit
Boards
Locations
="
*
"s+
5
4-2. Semiconductor Lead Layouts -**«*° =
4-3,
Printed
Wiring
Boards:
«++
*
ees
4-4,
Schematic
Diagrams
«=
ss
sss
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SECTION 5. EXPLODED VIEWS
5-1.
Chassis
Sections
**
* *
ss
ss
e
8s
5-2.
Front
Panel
Section:
«*
sss
es
8
5-3.
Mechanism
Section-l*
**
*
sss
es
5-4.
Mechanism
Section-2*
**
s
**
"
"85
SECTION
6.
ELECTRICAL
PARTS
LIST:
»-
+--+
«+55
MODEL IDENTIFICATION
(Specification Label)
TC-K370
TC-RX370
SONY:
STEREO CASSETTE DECK
LLL
MODEL NO,
US, Canadian model: ACI20V 60Hz 20W
UK, Australian model: AC240V ~50/60Hz
Germany, AEP model: AC220-230V ~ 50/60Hz
ATTENTION AU COMPOSANT AYANT RAPPORT
A LA SECURITE!
LES COMPOSANTS IDENTIFIES PAR UNE MARQUE /\
SUR LES DIAGRAMMES SCHEMATIQUES ET LA LISTE
DES PIECES SONT CRITIQUES POUR LA SECURITE
DE FONCTIONNEMENT. NE REMPLACER CES COM.
POSANTS QUE PAR DES PIECES SONY DONT LES
NUMEROS SONT DONNES DANS CE MANUEL OU
DANS LES SUPPLEMENTS PUBLIES PAR SONY.

TC-K370/RX370
SECTION 1
GENERAL
TC-K370
“Remote control sensor
Capteur de télécommande
|
]
be = 3
For details, refer to the page number indicated in@
{1} POWER switch > (rightward fast winding) button
¥t PAUSE button
{2} Cassette holder O REC MUTE (record muting) button @
ae @ REC (recording) button
{81 TAPE COUNTER sont
an iu: & EJECT button
14) RESET button Ones
: 2 HEADPHONES jack (stereo phone jack) @
(5) PEAK LEVEL METER ®
- *Remote control sensor
6! REC (recording) LEVEL control @ @® You can remotely control this cassette deck with:
a, — A remote commander that came with a Sony amplifier or
(7: BALANCE control @ receiver if it has the fd mark and cassette deck control
= capability.
(8! BIAS control © — An optional Sony remote commander with the EJ mark
'§} DOLBY NR (noise reduction switch) © @ and cassette deck control capability.
(10 Tape operation buttons
#4 (Jeftward fast winding) button
B (stop) button
b- (play) button
TC-RX370
“Remote control sensor
Capteur de télécommande
For details, refer to the page number indicated in @
[a
POWER switch O REC MUTE (record muting) button @
@ REC (recording) button
(2) Cassette holder
(14; & EJECT button
[3] TAPE COUNTER f A ‘
(19 HEADPHONES jack (stereo phone jack)
(4] RESET button 3 DIRECTION mode switch © @
{5}
St PEAK EVER METER © *Remote control sensor
[6] REC (recording) LEVEL control @ ® You can remotely control this cassette deck with:
— A remote commander that came with a Sony amplifier or
[7] BALANCE control ® receiver if it has the E3 mark and cassette deck contro!
x : capability.
[8] BIAS control ® — An optional Sony remote commander with the EJ mark
. . 7 and cassette deck control capability.
[9] DOLBY NR (noise reduction) switch @ @
[1G Tape operation buttons
«44 (leftward fast winding) button
™@ (stop) button
~w@ (reverse play) button
we (play) button
bP (rightward fast winding) button
#8 PAUSE button
This section is extracted
from instruction manual.

TC-K370/RX370 |
SECTION 2
DISASSEMBLY
Note: Follow the disassembly procedure in the numerical order given.
CASE
Unscrew the four case attachment screws M3 X8
and remove the case.
J CN805 @Femove the connectors.
FRONT PANEL
MECHANISM DECK
@Press the eject button. @Pull the counter belt
and put arround the claw.
SS—— @BVTP2.6x8
mechanism deck
Ocassette lid
=p Remove the cassette
holder assembly.
\

HEAD
(TC-K370)
@ screw \
(BVTT2 X 10) (y-
© screw(azimuth
adjustment)
@REC/PB head
HRP107
@ lever (pinch lever FWD) assy
FITTING BASE BLOCK
Oscrews (PTPWH2 X23)
Cee installing, pull the capstan belt and )
put around the claws as shown below.
TC-K370/RX370
(TC-RX370)
© claw
@head base ass’y
HRP102, HE102
O lever
og @ torsion spring
>
@ lever(pinch lever FWDjass‘y
Oconnectors
Oscrews(P2.6 X 2.8)
(When installing, pull the FR belt and put)
around the claws as shown below.

TC-K370/RX370 |
SECTION 3
ADJUSTMENTS
3-1. MECHANICAL ADJUSTMENTS
PRECAUTION
1. Clean the following parts with a denatured alcohol-
moistened swab:
record/playback/erase head (TC-RX370)
capstan idlers
2. Demagnetize the record/playback head with a head
demagnetizer.
(Head demagnetizer do not approach for the erase head.)
3. Do not use a magnetized screwdriver for the adjustment. |
4, After the adjustments, apply suitable locking compound
to the parts adjusted.
5. The adjustments should be perfomed with the rated
power supply voltage unless otherwise noted.
Torque Measurement
Torque Torque meter Meter reading |
30 to 65g ° cm
Forward C Q-102C
(0. 42 to 0.9 oz * inch)
DECK A: 1 to 6g- cm
Forward CQ-102C (0.014 to 0.08 oz + inch)
back tension DECK B : 2 to 9g*cm
(0.03 to 0.12 02° inch)
Reverse Ie 30 to 65g ° cm
C Q-l02RC
| (TC-RX370) (0.42 to 0.9 oz inch)
Reverse 1 to 6g-cm |
back tension C Q-102RC (0.014 to 0.08 oz ° inch)
(TC-RX370)
Sane ieee ee aa it
70 to 120g ° cm
FF, REW CQ-201B
(0. 98 to 1.87 oz ° inch)
3-2. ELECTRICAL ADJUSTMENTS
PRECAUTION
1. The adjustment should be performed in the publication.
(Be sure to make playback adjustment at first.)
2. The adjustment and measurement should be performed
for both L-CH and R-CH.
e Switch position
DOLBY NR switch : OFF
DIR MODE switch :2
e Standard record position
Deliver the standard input signal level to input jack and
set the REC LEVEL control to obtain the standard
output signal level as follows,
—Record Mode—
AF OSC
LINE IN LINE OUT
pinch roller
record/playback(TC-K370) erase head(TC-K370) rubber belts
Standard Input Level
Input terminal LINE IN
source impedance 10kQ
input signal level 0.25V (—10dB)
Standard Output Level
Output terminal LINE OUT
load impedance 47kQ
output signal level 0.44V (—5dB)
Test Tape
P-4-A100 10kHz, ~10dB Azimuth Adjustment
PB Level Adjustment
Tape Speed Adjustment
P-4-L300 315Hz, 0dB
WS-48B 3kHz, 0dB
0dB=0.775V
Record/Playback Head(TC-K370) Azimuth Adjustment
Record/Playback/Erase Head(TC-RX370)
Procedure:
1. Forward Playback Mode
test tape
P-4-A100
(10kHz, —10dB)
LINE OUT
2. Turn the adjustment screw for the maximum output
levels. If these levels do notmatch, turn the adjustment
screw until both of output levels match together within
1dB.
L-CH
peak
within 1dB
R-CH
peak
screw
position
screw
Eur R-CH ce angle

3. Phase check
Playback Mode
test tape
P-4-A100
(10kHz, —10dB) oscilloscope
L-CH 47kQ
eu LINE OUT
Screen pattern
in phase 45° 90° 135° 180°
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good wrong
4, Change the reverse playback mode and repeat the steps
1 to 3, (TC-RX370)
5. After the adjustment, lock the adjustment screw with
suitable locking compound.
Adjustment Location : — record/playback/erase head —
TC-K370
FWD(Adjustment screw)
TC-RX370
Adjustment screw
Tape Speed Adjustment
Procedure:
—Forward Playback Mode—
test tape
WS-48B
(3kHz, OdB) frequency counter
LINE OUT
Perform high speed adjustment before normal speed adjust-
ment.
(high speed adjustment)
1. Set to FWD playback mode.
2. Keep on pressing the HIGH SPEED DUBBING switch.
3. Adjust RV72 so that the frequency counter reading
becomes 6,000+30Hz.
(normal speed adjustment)
1. Set to FWD playback mode.
2. Adjust RV71 so that the frequency counter reading
becomes 3,000+10Hz.
Frequency difference between the beginning and the end of
the tape should be within 3%.
Adjustment Location: AUDIO board
Playback Level Adjustment
Procedure :
—Forward Playback Mode—
test, tape
P-4-L300
(315Hz, OdB)
LINE OUT
Adjust RV11 (L-CH) and RV21 (R-CH) so the VITVM
reading becomes the adjustment limits below.
Adjustment Value :
LINE OUT level: —5+0.5dB (0.412 to 0.461V)
Level Difference between Channels: within 0.5dB
Confirm the LINE OUT level does not change in playback
mode while changing the mode from playback to stop several
times.
Adjustment Location: AUDIO board

Bias Consumption Current Adjustment
This adjustment should be perfomed when replacing the head
assy or the bias oscillating transformer (T81, T91).
Procedure:
( ): R-CH
digital
voltmeter
blank tape
CS-413
set —_
LINE IN
no signal
Connect the digital voltmeter to test point TP81.
Set RV81 (RV91) to mechanical center.
Set to FWD record mode.
Adjust T81(T91) so that the digital voltmeter reading
becomes minimum.
ee Co Se
Adjustment Location: AUDIO board
Record Bias Adjustment
Setting :
REC LEVEL control: standard record position (Refer to
page 6.)
Procedure:
1. Record Mode
etek blank tape
CS-123
EE 5}
1) 315Hz
2) l1OkHz
LINE IN
} 31.6mV (—27.8dB)
2. Playback Mode
LINE OUT
Playbck the signal recorded in step 1.
Confirm that the 10kHz playback output is 0+0.5dB relative
to the 315Hz output. If necessary, adjust RV81 (L-CH), RV91
(R-CH) and repeat the steps given above.
Adjustment Location: AUDIO board
Record Level Adjustment
Setting:
REC LEVEL control: standard record position (Refer to
page 6. )
Procedure:
1. Record Mode
AF OSC
2) attenuator
oneee)
Wpaekenend
O-——-O O
Ld ENDL J
blank tape
CS$-123
LINE IN
315Hz, 31.6mV (—27.8dB)
2. Playback Mode
recorded
portion
LINE OUT
Confirm playback the tape recorded become adjustment level
as follows.
If necessary, adjust RV101 (L-CH), RV201 (R-CH) and repeat
steps 1 and 2.
Adjustment Value :
LINE OUT level: —27.8+0.5dB (29 to 33.4mV)
Adjustment Location: PANEL Board
—Adjustment Parts Location Diagrams—
{PANEL BOARD] (COMPONENT SIDE)
I
4
RV502
|_|
RV503 RV50I
| ie
L J
RVIO!
(L-CH)
RV201
(R-CH)
Record Level

(AUDIO BOARD)
(COMPONENT SIDE)
ae
a
RV81
(L-CH)
Bias
Consumption
Current
0)
|
if
IC81
RVQ1
|
Record
Bias
R-CH
=
=
RV72
AY
(HIGH)
Tabe
Speed
1
4
RV71
iB
a
(NORMAL)
TP81
4
31
oo
Bias
Consumption
T91
Current
(R-CH)
RV21(R-CH) \
RV11(L-CH)
Playback
Level