Technics RS-M14 User manual

ORDER NO. ARD-8004036C
Service Manual
Cassette Deck
RS-M14
( Silver load
Black Face
Metal Tape Compatible Stereo Cassette Deck
with Peak-Hold FL Meters, Soft-Touch Controls and
Rewind Auto-Play Convenience
DO [sacevavsrem)
This is the Service Manual for the
following areas.
wees For all European areas
except United Kingdom.
s+ For United Kingdom.
cei ass For Asia, Latin America,
Middle East and Africa
areas.
Al see sires For Australia.
a For Asian PX.
naib ants For European PX.
RS-M24 MECHANISM SERIES
Specifications
Track system: 4-track 2-channel stereo recording and playback Outputs: LINE; output level 420 mV, output impedance
Tape
speed:
4.8cm/s
1.5kQ
or
less,
load
impedance
22kQ
over
Wow and flutter: 0.05% (WRMS), +0.14% (DIN) oh output level 80mV, load imped-
; 2 ance
Prequeney esponces Metal Tapes oe na + (DIN) Rec/Pb connection: 5P DIN type;
CrOo/Fe-Cr tape: 20-18 000Hz input sensitivity 0.25 mV, impedance 5.3kQ
: pe; 3016 O00Hz (DIN) output level 420 mV, impedance 5.2kQ
Normal tape: 20—17,000Hz Bias frequency: 80 kHz
30—15,000Hz (DIN) Motor: Electrical DC governor motor
Signal-to-noise
ratio:
Dolby
NR
in;
67
dB
(above
5kHz)
Heads
:
2-head
system;
1-MX head for record/playback
Dolby NR out: 57 dB (signal level=max. record- i disubiecera tents heatl tov amseults
ing level, Fe-Cr/CrOz type tape)
Fast forward and Power requirements: AC; 110/125/220/240V, 50-60Hz
rewind time: Approx. 90 seconds with C-60 cassette tape Power consumption: 15 W (for European areas and Australia)
Inputs: MIC; sensitivity 0.25 mV, input impedance 25kQ 13 W (for Asia, Latin America, Middle East, Africa
over applicable microphone impedance 4002— areas and PX.)
Dimensions: 43,0cm(W) X 11.9cm(H) x 24.6cm(D)
LINE; sensitivity 60mV, input impedance 40kQ2 Weight: 4.3kg
Specifications are subject to change without notice.
* ‘Dolby’ and the double-D symbol are trademarks of Dolby Laboratories.
@ Panasonic Tokyo
ec | 2 1CS Matsushita Electric Industrial Co., Ltd. Matsushita Electric Trading Co., Ltd.
17-15, 6-chome, Shinbashi, Minato-ku, Tokyo 105 Japan P.O. Box 288, Central Osaka Japan

RS-M14
CONTENTS
ITEM | PAGE
LOCATION
OF
CONTROLS
AND
COMPONENTS
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DISASSEMBLY
INSTRUCTIONS
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DISASSEMBLY
NOTES
(MECHANISM
UNIT)
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ASSEMBLY INSTRUCTIONS: se: s2ssssee2sssais coscsssnasgencmeseersanancs sas anos cemncmemonscemaeananmaeacneas 4
ADJUSTMENT
PARTS
LOGATION:
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MEASUREMENT
AND
ADJUSTMENT
METHODS
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6
ELECTRICAL
PARTS
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WIRING CONNECTION DIAGRAM AND CIRCUIT BOARDS '::+erseccereeceeceeteecenteeeeeeeaeeneees 10
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MECHAMICAL
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LOCATION OF CONTROLS
AND COMPONENTS
@ Power switch
@ Cassette holder
@® _ Headphones jack
@ Eject button
® Record button
© Rewind/review button
@ Fast forward/cue button
Playback button
@ Stop button
Pause button
@ Input selector
@ Dolby noise-reduction switch
@) Tape selector
(tape select-normal/Fe-Cr/CrO2/metal)
Record muting button
@® Input level controls
Tape counter and reset button
@ Record indication lamp
FL (fluorescent level) meter
Microphone jacks
@ Line output jacks
@) Record/playback connection socket
@ Line input jacks
@ Voltage selector

RS-M14
DISASSEMBLY
INSTRUCTIONS
* The head azimuth can be
adjusted
by
removing
the
(C)
cassette lid.
To
remove
——
. :
|
Shown
in
fig.
——.
Case
cover
°
4
screws
3
—
Bottom cover ° 3 screws
* 2 control knobs
Front panel ° Cassette lid
° 4 screws
WwW] ks
&
ol
° 4 red screws
° Tape select knob
* 3 push buttons
° 4 screws
Main circuit board
¢ Cassette holder
° 2 black screws
¢ 4 screws
Chassis cover assembly and
mechanism unit
CO}INNNINNN®D
Operation button assembly ° 2 screws

RS-M14
DISASSEMBLY NOTES
© Precautions for removal of the motor
When
removing
the
motor,
follow
the
procedure
given
below.
1.
Remove
screw
(A),
and
then
detach
flywheel
retainer
(M44)
by
pulling
it
in
the
direction
of
the
arrow
as
in
fig.
9.
2.
After
removing
screws
(B),
detach
takeup
belt
(M78)
and
capstan
belt
(M76),
and
then
sub
chassis
assembly
(M72)
can
be
rernoved.
(fig.
9,
10)
3.
When
screws
(C)
is
removed
after
detaching
fast
forward
belt
(M77),
motor
assembly
(M71)
can
be
removed.
(fig. 10)
Fast Forward
Belt(M77) Screw(C)
Sez"
2 | iy
ee Tews
Sub Chassis Assembly (M72)
Fig. 10
©
Head
base
plate
(M57)
and
upper
base
plate
(M83)
removing
procedure
1.
With
screw
(D)
removed,
head
base
plate
pressure
spring
(M66)
can
be
detached.
In
this
case,
take
care
not
to
lose
steel
ball
(M65).
(fig.
11)
2.
With
head
release
spring
(M68)
removed,
head
base
plate
(M57)
can
be
detached.
(fig.
11,
12)
In
this
case,
take
care
not
to
lose
steel
ball
(M65)
and
roller
(M64).
3.
After
removing
pressure
roller
release
spring
(M25),
remove
pressure
roller
assembly
(M40).
(fig.
12)
4,
Remove
screw
(E),
and
then
upper
base
plate
(M83)
can
be
detached.
(fig.
12)
(MECHANISM UNIT)
Sub
Chassis
Assembly
(M72)
Takeup
Belt
(M78)
Screw
(A)
Capstan
Belt
(M76)
/
Flywheel Retainer(M44) ;
Flywheel a 1
Retaimer (m44)—
|
1
!
|
|
|
!
1
|
|
I
|
|
!
Head Base Plate
Pressure
Spring(M66)
Head
Base
Plate(M57)
|
Screw(D)
Steel
Ball(M65)
Head
Release
Spring(M68)
Fig. 11
Steel Ball(M65) Roller(M64) Pressure Roller
Release Spring (M25)
Upper Base
Plate(M83)
Screw(E)
Pressure
Roller
Assembly
(M40)
Fig. 12

MECHANISM SECTION
1. For repair, measurement or adjustment with the mechanism
removed from the unit be sure to ground the lower base
plate of the mechanism.
2. For grounding, connect a extension cord to the mechanism's
lower base plate and the Lug terminal from main
circuit board.
3. Without grounding, the amplifier does not operate properly.
Fig. 13
ASSEMBLY INSTRUCTIONS
; Capstan Belt (M76)
e
Belt
mounting
Fast
Forward
Belt
(M77)
Takeup Belt (M78)
Check that each belt is free of damage or grease on the
surface, after that, set the belt as illustrated, and mount it on
the lower base plate (M84) after that, set the takeup belt
(M78) on the fast forward connection pulley assembly
(M82).
é
Fig. 14
@ Positioning the takeup reel table assembly 1 RS dakodties
Detection Lever M50: Takeup Reel
When
installing
the
takeup
reel
table
assembly,
be
sure
to
Table
Assembly
mount
the
auto-stop
friction
hub
(shown
in
fig.
16),
as
illustrated
in
fig.
15.
If the takeup reel table is positioned incorrectly at any place
other than that shown in fig. 15, the auto-stop mechanism
remains operative at all times.
Auto-Stop
Auto-Sto
. .
i
Pp
Friction
Hub
Friction
Hub
Fig. 16
@
How
to
install
the
flywheel
retainer
PAS
WAS
REbAIRE
1. Insert the thrust retainer into the hole @) of the flywheel Hole ®
retainer as shown in fig. 17.
2. Hold the thrust retainer with the thumb as shown in ;
fig. 18. GS ) Thrust Retainer
Flywheel
Hold this part with the thumb
Fig. 17 Fig. 18

3. Engage the parts @) and © of the flywheel retainer with
the lower base plate as shown in fig. 19.
4. Shift down the flywheel retainer, supported at points ©,
in the direction of the arrow as illustrated. (fig. 20)
5. Attach the screw (A) in the position as shown in fig. 9.
e Mounting the operation button assembly
Before mounting the operation button assembly on the
mechanism body, be sure to lift the main control lever in the
direction of the arrow using a screwdriver, as shown in fig.
21, until it locks in place.
M8: Main Control Lever
Hub of the
Playback
Button Assembly.
Screwdriver
If it is not mounted in this manner, the hub of the playback —
button assembly during playback catches on the main control
lever, making it impossible to release playback mode. Spt eOM EET ON Meaty
Fig. 21
Tape Speed Adjustment VR.
TP3 TP4 TP2 TP5 TP6 TP8~ TP7
VR7
VR8&
TPl
L2
L1
VR6
tp ii. %
i \
R6 6) /
ee
poe
ra Ss TP9 TP10
/ TP12
4 R62! VR5 VR402 VR1 VR2 VR401
NY F
5 Fig. 22

MEASUREMENT AND
ADJUSTMENT
METHODS
NOTES: Keep good condition, set lever switches and controls in the following positions, unless otherwise specified.
@ Make sure heads are clean.
@ Make sure capstan and pressure roller are clean.
© Judgeable room temperature: 20-£5°C (68+9°F)
e Dolby NR switch: OUT
ITEM MEASUREMENT & ADJUSTMENT
® Head position
adjustment
Condition:
* Playback and pause mode
® Head azimuth
adjustment
Condition:
* Playback mode
Equipment:
*VTVM — * Oscilloscope
* Test tape (azimuth)
---QZZCFM
* Test tape (tape path viewer)
@ Tape speed
Condition:
* Playback mode
Equipment:
* Digital electronic counter or
frequency counter
* Test tape --- QZZCWAT
“2. Playback this tape.
® Tape selector: Normal position
@ Input selector: Line in
@ Input level controls: Maximum
Screw (A) —
Head Adjusting Plate
Capstan
)
(B)
4
Pressure Roller
(The head adjusting plate is provided to adjust the tape
touch of the head in cue or review mode.)
1. Press the playback button and pause button.
2. Measure the space between the pinch roller and the
capstan.
Standard value: 0.5+0.3mm
Space (adjustable)
3. If the measured value is not within the standard value,
untighten screw (A), and slide the head adjusting plate
in the direction of arrow (B) for adjustment.
Record/playback head azimuth adjustment
1. Test equipment connection is shown in fig. 24.
2. Playback azimuth tape (QZZCFM 8 kHz).
3. Adjust record/playback head angle adjustment screw (B)
LINE OUT
Playback
mode
VTVM
Oscilloscope
in fig. 25 so that output level at LINE OUT becomes “*™* Fig. 24
maximum.
4. Measure both channels, and adjust levels for equal output.
5. After adjustment lock head adjustment screw with lacquer.
Record/playback mode Erase head
Erase head azimuth adjustment
1. Test equipment connection is the same above but use the
tape path viewer (QZZCRD) instead of test tape (QZZCFM).
fh fe
(B)
Fig. 25 Fig. 26
3. Adjust screw (C) shown in fig. 26 so that the tape may not
get curled or malformed by tape guide of the erase head.
. After adjustment, lock head adjust screw with lacquer.
Tape speed accuracy
1. Test equipment connection is shown in fig. 27.
2. Playback test tape (QZZCWAT 3,000Hz), and supply
playback signal to frequency counter.
3. Measure this frequency.
4. On the basis of 3,000Hz, determine value by following
formula:
Test tape Playback mode Digital electronic counter
Fig. 27
f — 3,000
3,000
. Take measurement at middle section of tape.
Tape speed accuracy = x 100(%) where, f= measured value
Standard value: 1.5%
Adjustment method
1. Playback the test tape (middle).
2. Adjust so that frequency becomes 3,000 Hz.
3. Tape speed adjustment VR shown in fig. 22.

ITEM MEASUREMENT & ADJUSTMENT
® Playback frequency
response
Condition:
* Playback mode
* Tape selector
~ ++»Normal position
Equipment:
*VTVM — * Oscilloscope
* Test tape--- QZZCFM
@ Playback gain
Condition:
* Playback mode
* Tape selector
--- Normal position
Equipment:
*VTVM — * Oscilloscope
* Test tape--- QZZCFM
Tape speed fluctuation
Make measurements in same manner as above (beginning, middle and end of tape), and determine the
difference between maximum and minimum values and calculate as follows:
f= F2_ 5 100 (96)
————— f1=maximum value, f2 = minimum value
3,000
Tape speed fluctuation =
Standard value: Less than 1%
Note:
Please use non metal type screwdriver when you adjust tape speed accuracy on this unit.
Pe
Playback frequency response chart
12.5kHz
1. Test equipment connection is shown in
fig. 24.
2. Place UNIT into playback mode.
3. Playback the frequency response test
tape (QZZCFM).
. Measure output level at 315Hz, 12.5kHz,
8kHz, 4kHz, 1kHz, 250Hz, 125Hz and
63 Hz, and compare each output level
with the standard frequency 315 Hz, at
LINE OUT.
. Make measurement for both channels.
. Make sure that the measured value is
within the range specified in the frequency response chart.
63Hz 125Hz
200Hz 500Hz 1KHz
500Hz 1kHz
Fig. 28
63Hz125Hz 200 Hz
. Test equipment connection is shown in fig. 24.
. Playback standard recording level portion on test tape (QZZCFM 315Hz), and using VT VM measure
the output level at LINE OUT.
. Make measurement for both channels.
| Standard value: around 0.39V
Adjustment
1. If measured value is not within standard, adjust VR1 (L-CH), VR2 (R-CH) (See fig. 22 on page 5).
2. After adjustment, check “Playback frequency response” again.
@ Bias leakage
Condition:
* Record mode
* Input level controls --- MAX
* Tape selector
--» Metal position
Equipment:
*VTVM — * Oscilloscope
@ Erase current
Condition:
* Record mode
* Tape selector
--» Metal position
Equipment:
*VTVM — * Oscilloscope
1. Test equipment connection is shown in fig. 29. page
2. Place UNIT into record mode.
3. Adjust trap coil L1 (L-CH), L2 (R-CH) so that measured
value on VTVM becomes minimum.
4. Take adjustment for both channels.
TPS(L-CH)
Record /playback
head
Record mode
Fig. 29 Vtvm_ Oscilloscope
1. Test equipment connection is shown in fig. 30.
2. Press the record and pause buttons.
3. Set the tape selector to metal position.
4. Read voltage on VT VM and calculate erase current by
following formula:
Erase head
Voltage across both ends of R301
1(Q)
Era
rrent
(A)
=
VIVM
Oscillos
se
curre
t
(
)
VTVM
Oscilloscope
Fig. 30
Standard value: 155+15mA (Metal position) |
5. If measured value is not within standard, adjust as follows.
Adjustment
1. Open the point (A) and short the point (B) on the main circuit board in the wiring connection diagram
(See page 10).

Ee he ae
ITEM MEASUREMENT & ADJUSTMENT
2. Make measurement for erase current.
3. Make sure that the measured value is within the erase current of 140mA to 170 mA.
4. lf it is beyond the value, carry out the following adjustments:
@® Bias current
Condition:
* Record mode
* Tape selector
-- Normal position
--Fe-Cr position
--CrOz position
-- Metal position
Equipment:
*VTVM * Oscilloscope
@ Overall gain
Condition:
* Record/playback mode
* Input level controls --- MAX
* Standard input level;
MIC +++++++- —72+4dB
LINE IN--- —-2444dB
Equipment:
*VTVM * AF oscillator
* ATT * Oscilloscope
* Resistor (600 2)
* Test tape
(reference blank tape)
--QZZCRA for Normal
® Overall frequency
response
Condition:
* Record/playback mode
* Tape selector
-- Normal position
--Fe-Cr position
--CrO2 position
-- Metal position
* Input level controls --- MAX
Equipment:
*VTVM * AF oscillator
* ATT * Oscilloscope
* Resistor (600 2)
* Test tape
(reference blank tape)
--QZZCRA for Normal
--QZZCRY for Fe-Cr
--QZZCRX for CrOz
--QZZCRZ for Metal
. Test equipment connection is shown in fig. 31.
. Place UNIT into record mode, and tape selector to normal
. Read voltage on VT VM and calculate bias current by
4
3;
6
Note:
Before measuring and adjusting, make sure of
the playback frequency response (For the
. Place UNIT into record mode, and tape selector to normal
p
° If the erase current is less than 140 mA, short the point (A).
° If the erase current is more than 170mA, open the points (A) and (B).
VR7 (L-CH)
VR8 (R-CH)
oa Record/playback
head
position.
Record mode
TP1(L-CH) ;
TP2IR-CH)
R1 (L-CH)
R2 (R-CH)
following formula:
Value read on VTVM (V) VTVM_ Oscilloscope
10 (Q)
Bias current (A) =
Fig. 31
Standard value: around 410A (Normal position) :
. If measured value is not within standard, adjust VR7 (L-CH) and VR8 (R-CH) (See fig. 22 on page 5).
Set the tape selector to each position.
. Make sure that the measured value is within standard.
Standard value: around 440A (Fe-Cr position), around 545A (CrO2 position),
around 800A (Metal position)
est equipment connection is shown in fig. 32. Kasnitiaiies
head i
osition.
. Supply 1kHz signal (—24dB) from AF oscillator, through
ATT to LINE IN.
djust ATT until monitor level at LINE OUT becomes Record/playback
39V.
head
Record mode
Test tape
AF oscillator
A
0.
. Using test tape, make recording.
. Playback recorded tape, and make sure - value at LINE
—7 dB).
. If measured value is not 0.39 V, adjust VR5 (L-CH), VR6
(R-CH) (See fig. 22 on page 5).
. Repeat from step (2).
Playback mode yTVM Oscilloscope
Fig. 32
OUT
on
VTVM
becomes
0.39
V
(
Test
tape
Overall frequency response chart (Normal)
10kHz
seit 100s 640 Hz 2kHz 4kHz
method of measurement, please refer to the
playback frequency response).
1.
2.
3.
. Supply 1kHz signal from AF oscillator
. Record each frequency 1 kHz, 50Hz,
Test equipment connection is shown in
fig. 32.
Place the normal test tape (QZZCRA) in
the cassette holder.
Place UNIT into record mode, and tape
selector to normal position.
: 100Hz Fig, Hz 2kHz
33
50Hz
Overall ee response chart
(Fe-Cr, CrO2, Metal)
2kHz
12kHz
through
ATT
to
LINE
IN.
200
Hz
640
Hz
. Adjust ATT so that input level is —20dB
below standard recording level (standard
recording level=0 VU).
. At this time, LINE OUT level indicates
0.039V.
200 Hz. 640 Hz
200Hz, 4kHz, 8kHz and 10kHz (12kHz
Fig. 34
for
Fe-Cr,
CrOz
and
metal).
mee
50Hz
. Playback and express in dB the difference between ‘plavbaek output level of each frequency based on
playback output level of 1 kHz.

. Make sure that the measured value is within the range specified in the overall frequency response chart
(Shown in fig. 33).
. Change test tape to Fe-Cr (QZZCRY), CrO2 (QZZCRX) and metal (QZZCRZ).
. Set the tape selector to each position.
. Measure in the same manner from step (3) to step (8).
. Make sure that the measured value is within the range specified in the overall frequency response chart
for Fe-Cr, CrO2 and metal tape (Shown in fig. 34).
Adjustment — Using bias current
1. When the frequency response between the middle and high
frequency range becomes higher than the standard value, as *
shown by the solid line in fig. 35’ increase, refer to bias
current adjustment.
. When it becomes lower, as shown by dotted line, refer to
bias current adjustment.
Note:
For the method of bias current measurement, refer to “Bias
current adjustment” on page 8.
1kHz = 2kHz ; 8kHz 12kHz
@ Fluorescent meter . Test equipment connection is shown in fig. 32.
Condition: . As shown in‘tig. 36, connecting the base of Q402 and
* Record mode ground stops the oscillation of the astable multivibrator
* Input level controls --- MAX comprising Q402 and Q403.
* Tape selector . Supply 1kHz signal (—24 dB) to the LINE IN then press
.-- Normal position the record button.
. Adjust the ATT so that the output level at LINE OUT
becomes 0.39V (The input level at this condition is termed
the standard input level).
. Adjustment at “—20 dB”:
A. Adjust the ATT so that the input level is —20dB below
standard recording level. ao
B. Adjust VR401 so that the —20dB segment at
ights
up
in
the
~200.8dB
range
(L-CH
—.
SU/IIIMIUIIIIIIIIIIIIIIIIIIIIIIUIIUI1111111111HIHI1
only) (See fig. 37). ray
. Adjustment at “OdB”: 2 6+ 4°25 0 2 00 +66
A. Adjust the ATT so that the output level at Fig. 37
LINE OUT becomes 0.39 V. ei scence
(The input level at this condition is termed MYTYTETTYYT TTY = (+108)
the standard input level.) STMT UU MT
. Adjust VR402 so that the +1dB segment a; el a oe ak an
lights up in the O+0.2dB range of the pan lhe abated
standard input level (See fig. 38). ":
. Repeat twice between steps (5) and (6) above. Mmm ccc cece
. Adjust ATT and check that all segments lights shaven asuaaaviasiauiatas Sarasa
up when an input signal level is increased to STILT ATLA UU
10 dB higher than the standard input level (See 20 PEAK) 6 * 42+ 20 2 («6 8» (1048)
Equipment:
*VTVM — * AF oscillator
* ATT * Resistor (600Q)
@ Dolby NR circuit . Test equipment connection is shown in fig. 40.
Condition: . Place UNIT into record mode, set the Dolby NR switch
* Record mode to OUT position and supply to LINE IN to obtain
* Dolby NR switch --- IN/OUT —34.5dB at TP11 (L-CH), TP12 (R-CH) (frequency cron TPL CH)
* Input level controls --- MAX 5kHz). ae ea
. Confirm that the value at IN position is 8(+2.5)dB LINE IN [X (ieee
Equipment:
se
Q
fee
aa
ter
than
the
value
at
OUT
position
of
Dolby
NR
1
*VTVM
+
AF
oscillator
a.
P
y
SOL
OOOO
OQ.
*
ATT
*
Oscilloscope
:
AF
oscillator
ATT
Record
mode
©
VTVM
*
Resistor
(600
Q)
Fig.
40