Panasonic RS-612US-E User manual

ORDER
NO.
ARD-7707065C
Service
Manual
Cassette Deck
10050093 1004988 23
SM=-RS612
RS-612
S-E
SERVICE MANUAL [ J
Front
Loading
Stereo
Cassette
Deck
with
Dolby*
Noise-Reduction
System,
Timer
Stand-By,
and
Bias
and
Equalization
Switches
RS-630U
MECHANISM
SERIES
Specifications
(Catalog
specifications
for
sales)
Power
requirement:
AC;
90~109/110~125/200~219/220
Fast
forward
and
~250V,
50/60Hz
rewind
time:
Approx.
90
seconds
with
C-60
cassette
tape
Power
consumption;
10
W
Input:
MIC;
sensitivity
0.25
mV/applicable
microphone
Motor:
1-electronic
speed
contro!
motor
impedance
4002~20KQ
.
Track
system:
4-track,
2-channel
stereo
recording
and
playback
LINE
;
sensitivity
60
mV/input
impedance
90
KQ
Tape
speed:
4.8cm/s
DIN;
sensitivity
0.25
mV/input
impedance
1.8KQ.
Wow
and
flutter:
0.12%
(WRMS),
+£0.25%
(DIN)
LINE;
output
level
420
mV/load
impedance
,
22
KQ
over
Frequency
response:
CrO2z
tape;
30~15,000Hz
:
40~14,000Hz
(DIN)
Head:
2-head
system
Normal
tape;
30~
13,000Hz
l-super
permalloy
head
for
record/playback
40
~
12.000
Hz
(DIN)
1-double-gap
ferrite
head
for
erasure
Signal-to-noise
ratio:
Dolby
NR
in;
65
dB
(above
5
kHz)
Dimensions:
41.0cm(W)
x
13.6cm(H)
x
24.4cm(D)
Dolby
NR
out;
55dB
Weight:
4kg
(signal level = max. recording level)
Specifications
are
subject
to
change
without
notice.
a
B
a
‘a
a
National
Panasonic
pareeniiy
Cleattic
Medina
Co.
Ue

LOCATION OF CONTROLS
AND COMPONENTS
QDO® ® @ ©)
©
OD ®O®D 1 dU 1913 1
Fig. 1
@ Door open button @ Rewind button @D Recording indication lamp
@ Power switch (® Fast forward button 48) Dolby noise-reduction switch
@ Cassette compartment door a) Playback button (9 Bias selector
@ Tape counter and reset button a2 Stop button @0 Equalizer selector
) Level/VU meter 3) Pause button @) Input selector
© Headphones jack Timer stand-by button @2 Line output jacks
@® Eject button 5) Microphone jacks @3) Record/playback connection socket
Record button d6) Record level adjustment @ Line input jacks
DISASSEMBLY INSTRUCTIONS
Fig. 3
To remove Remove: -—-. : Shown in fig. -—— .
Case cover
Bottom cover
Main P-C.B.
Mechanism

ADJUSTMENTS
Before measuring and adjusting “Overall frequency response’, “Overall distortion” and “Overall S/N ratio”, confirm that the characteris-
tics of 5 items below are within standard which have much relation to or influence on electrical performances above.
1. Head azimuth adjustment. 2. Bias current. 3. Playback gain. 4. Overall gain.
5. Playback frequency response.
I. TEST INSTRUMENTS
1. Prepare test instruments which are equivalent in accuracy to those shown below.
2. The test instruments should be inspected and corrected by specialists once every 6 months, because a long period of use without
maintenance may increase errors in indication.
3. Warm-up the test instruments for 30 minutes and the set to be measured for 10 minutes before taking the measurements. If not,
there may arise an error or difference between the initial value and the stabilized value measured after “aging”.
4. Specifications of test instruments.
(1) Audio frequency oscillator
a. Oscillation froquency: 5Hz~ 500 kHz (5 ranges)
b. Frequency tolerance: +(3% +1Hz)
c. Sine wave
* Output voltage (at 25°C): 5 Vrms + 10% (without load)
2.5Vrms + 10% (with 6002 load)
* Output frequency response: Within £0.2dB, 20Hz~ 20 kHz
Within +0.5dB, 5Hz~ 500 kHz
« Distortion factor: Not more than 0.05%, 200 Hz ~~ 20 kHz
Not more than 0.5%, 5Hz~ 500 kHz
* Output impedance: 6002 unbalanced, within + 15%
* Output attenuator: OdB, 20dB, Error: within +0.2dB
d. Temperature in use of set: Temperature = 0 ~ 40°C, Humidity =90% or less
(2) Automatic-stop distortion meter (with vacuum tube voltmeter)
A. Distortion factor measurement
a. Frequency (fundamental wave): 400Hz, 1kHz +10%
b. Measurement: ; 0.1~ 100% (6 ranges)
c. Input: 50mV ~50V
d. Fundamental wave attenuation: 60dB8 or more
B. Level measurement
a, Measurement: 1mV (—60dB) ~30V (30dB) (9 ranges)
b. Frequency response (1 kHz basis): 20Hz~ 100kHz +0.3dB
c. Input impedance: 1MQ +10%, less than 50 pF
d. Error in indicated value: Within £3% at 1kHz
C. Output terminal
a. Frequency response: 10Hz~100kHz £1dB
100kHz~1MHz +3dB
b. Output voitage: Vrms += 10% (1kHz sine wave)

(3) Attenuator
a. Input impedance: 6002 unbalanced
b. Maximum attenuation: 121dB
c. Minimum attenuation: 0.1dB
servis
(4) Oscilloscope
a. Cathode ray tube: Effective ranges 8 x 8cm
b. Vertical axis
* Input sensitivity : 30 mV ~ 30 V/cm
* Frequency band: DC ~2MHz
* Transient time: 180ns.
* Input impedance: 1MQ, 35 pF
c. Horizontal axis
« Tuning range: 30Hz ~ 2 MHz
* Sweep time: lus~100ms/cm
* External sweep: 1Vp-p/cm or more
(5) Digital electronic counter
a. Number of figure: 4 (decimal system)
b. Input sensitivity: 100 mVrms
c. Input impedance: 1MQ, 40 pF
d. Frequency measurement range: 10 Hz ~ 100 kHz
e. Counting time: 0.1, 1, 10s
(6) Wow meter
a. Measured center frequency range: 3kHz 4%
b. Input level range: 30mV~3V
c. Input impedance: About 50 KQ unbalanced
d. Measurement: 0.01~3% (5 ranges)
e. Indicator error: Maximum error in indicated value +5% in
each range.
f. Frequency response: Conforming to weighting curve characteristics
(WRMS), JIS C5551.
Flat characteristics (RMS)
0.5~200Hz, within —3dB (4Hz basis)
g. Meter indication system: Effective value indication, conforming to
JIS C5551.
h. Meter response characteristic: About 5~ 7 sec.
i. Oscillation frequency : 3 frequencies (3kHz, 3kKHz +3%)
J. Temperature range: O0~40°C

ll.
MEASUREMENT
CONDITIONS
1. Standard measurement conditions
«
Ambient
temperature:
10~30°C
(50~86*)
*
Ambient
humidity
:
30~90%
RH
* Power voltage accuracy: +3%
2. Position of tape recorder
+
When
measuring,
place
the
unit
under
test
in
a
horizontal
position.
3. Oscillator output voltage adjustment
*
Connect
the
equipments
as
shown
in
the
following
and
adjust
the
oscillator
output
control
knob
for
1V
(f=1kHz)
through
the
attenuator
while
keeping
the
attenuator
at
OdB.
+
When
supplying
a
signal
to
the
tape
recorder
amplifier,
adjust
the
input
level
using
the
attenuator.
Output control knob
Resistor 600Q
Audio
frequency
oscillator
j
Attenuator
i
Vacuum
tube
voltmeter
Oscilloscope
lil. TEST TAPE
Test tape life
The
more
frequently
the
test
tape
is
used,
the
more
the
tape
characteristics
will
deteriorate
(e.g.
lowering
of
recorded
level,
worsening
of
frequency
response
particularly
in
high-frequency
range,
and
an
increase
in
wow
due
to
tape
elongation)
until
meas-
ured
values
become
unreliable.
Even
in
such
a
case
when
a
tape
is
not
used,
but
stored,
for
a
long
period
of
time,
tape
shows
deterioration
in
performance
because
of
self
damagenetization
due
to
storage
conditions,
etc.
Please
refer
to
the
tape
life
specification
and
use
care
not
to
use
a
tape
longer
than
its
rated
life
when
servicing
Frequence
of
use:
Not
more
than
20
times
for
each
tape
length.
Storage period: Not more than 6 months.
* Test tape
PARTS
NO.
PARTS
NAME
|
SPECIFICATIONS
REMARKS
STANDARD
REC.
5
TIMES
REPETITIVE
RECORDING
LEVEL
&
FREQ.
|
TAPE
SPEED:
1-7/8IPS.
(4.8CM/S),
RESPONSE
TAPE
#
FULL
TRACK
(10
MIN.)
OdB: STANDARD REC. LEVEL (160pWb/mm)
—10dB
WOW & TAPE TAPE SPEED: 1-7/8IPS. (4.8CM/S),
SPEED
TAPE
3kHz
|
FULL
TRACK
(45MIN)
OdB: 250pWb/mm
-10 dB
|
TAPE
SPEED:
1-7/8IPS.
(48CM/S).
AZIMUTH
TAPE
6.3kHz
FULL
TRACK
(15MIN)
0d8: 250pWb/mm
REFERENCE BLANK
TAPE
(NORMAL)
UNRECORDED
TAPE
(20MIN.)
!
REFERENCE BLANK
ESO
|
|
UNRECORDED
TAPE
(20MIN.)

IV. MEASUREMENT & ADJUSTMENT METHOD
NOTE:
1. Make sure heads are clean. 4. Dolby NR switch: OUT
2. Make sure capstan and pressure roller are clean. 5. Bias selector: LOW
3. Judgeable room temperature: 20+5°C (68 +9°F) 6. Equalizer selector: 120uS
ITEM MEASUREMENT & ADJUSTMENT REMARKS
Pressure of pressure roller | 1. Place UNIT into playback mode. * Playback mode
Equipment: 2. Hook the tension gauge to pressure roller lever and pull it in the direc-
tion of the arrow as shown in fig. 6.
. Measure the tension at the moment when the pressure roller moves
away from the capstan.
Standard Value: 400+ 50 gr |!
* Tension gauge (max. 500 gr)
Adjustment method
O Bend the part (A) of the pressure roller spring in either direction shown
by the arrow until the correct pressure is attained.
spring
Fig. 6
Takeup tension 1. Mount cassette torque meter on UNIT. * Playback mode
Equipment: 2. Place UNIT into playback mode and read takeup torque.
* Cassette torque meter 3. Measure several times and determine the mean value
(SRK-CT or RP8063) r
| Standard Value: 55+ 15 gr-cm
* Playback mode
Head azimuth adjustment Record/playback head adjustment
Equipment: 1. Test equipment connection is shown below.
* VTVM
* Oscilloscope
* Test tape (azimuth)---C-AA
R/P head
LINE OUT iS
Test tape Playback mode VIVM Oscilloscope
Fig. 7
. Play azimuth tape (C-AA 6.3 kHz).
3. Adjust record/playback head angle adjustment screw (B) in fig. 8 so Fig. 8
that output level at LINE OUT becomes maximum.
4. Measure both channels, and adjust levels for equal output
_ After adjustment lock head adjustment screw with lacquer.

Tape speed
Equipment:
* Test tape---C-WAT
* Digital electronic couriter or
frequency counter (RP8067)
MEASUREMENT & ADJUSTMENT
Tape speed accuracy
1. Test equipment connection is shown below.
LINE OUT
Test tape Playback mode
Fig. 9
quency counter.
3. Measure this frequency.
Tape speed accuracy = 0 x 100) %
where, f = measured value
5. Take measurement at middle section of tape.
]
Standard Value: 1.5%
Adjustment method
1. Play the test tape (middle).
quency becomes 3,000 Hz.
Tape speed fluctuation
values and calculate as follows:
Tape speed fluctuation = (Sat- x 100} %
fi =maximum value
f2 = minimum value
Standard Value: 1% |
Digital electric counter
. Play test tape (C-WAT 3,000Hz), and supply playback signal to fre-
4. On the basis of 3,000Hz, determine value by following formula:
2. Adjust the tape speed adjustment VR shown in fig. 20 so that fre-
Make measurements in same manner as above (beginning, middle arid
end of tape), and determine difference between maximum and minimum
REMARKS
* Playback mode
Wow and flutter
Equipment:
* Wow meter
* Test tape---C-WAT
1. Test equipment connection is shown below
LINE OUT
Test tape Playback mode Wow meter
Fig. 10
wow meter.
can be weighted by JIS network (WRMS).
. Measure at middle section of test tape.
r
Standard Value: 0.17% (WRMS) |
.
Use
wow
test
tape
(3,000Hz)
and
measure
its
playback
signal
on
3. Wow and flutter is expressed in percentage and that measurement
* Playback mode

Playback frequency
_ Test equipment connection is as same as “Head azimuth adjustment”
MEASUREMENT & ADJUSTMENT REMARKS
* Playback mode
response
Equipment:
*VTVM
* Oscilloscope
* Test tape---C-FH
Playback gain
Equipment:
*VTVM
* Oscilloscope
* Test tape---C-FH
but use the test tape (C-FH) instead of head azimuth tape (See fig.
11).
. Place UNIT into playback mode.
. Play frequency response test tape (C-FH).
. Measure output level at 10kHz, 8kHz, 4kKHz, 1kHz, 125Hz and 63Hz
and compare each output level with standard frequency 333Hz, at
LINE OUT.
. Make measurement for both channels.
Make sure that the measured value is within the range specified in the
frequency response chart.
Playback frequency response chart
400H2
125Hz — 250Hz 6.3kHz 10kHz
Fig. 11
Adjustment
1. If the measured value decreases at high frequency range.
* Short the connection point (A) or unsolder connection point (C)
See fig. 19 on page 12.
lf the measured value increases at high frequency range
* Short the connection point (B) or (C).
. Test equipment connection is shown in fig. 7.
Play standard recording level portion on test tape (C-FH 333 Hz), and
using VTVM measure the output level at LINE OUT jack
Make measurement for both channels.
* Playback mode
| Standard Value: 0.42V (—7dB) |
Adjustment
1. If measured value is not standard, adjust VR3 (L-CH), VR4 (R-CH)
(See fig. 20 on page 12)
2. After adjustment, check “Playback frequency response” again
Playback S/N ratio
Equipment:
* VTVM
* Oscilloscope
* Test tape---C-FH
+ Empty cassette
2. Play standard recording level test tape (C-FH 333Hz) and read out-
. Test equipment connection is shown tn fig. 7.
put level on VTVM.
Refer to “Playback gain adjustment”.
. Place empty cassette (which has been cut) and play again.
_ Measure noise level at this time using VTVM, and determine ratio of
this level to test tape output signal voltage (333 Hz)
|
|
* Playback mode
[FS es CpG = a }
| Standard Value: Greater than 46dB |
i ah H

MEASUREMENT & ADJUSTMENT
An exampie calculation is shown below.
A: Es = playback output signal voltage of test tape (333Hz)
B: En=playback output noise level
Es =0.42V (—7dB)
En=2.1mV (—53 dB)
. Es 0.42V
S/N ratio = En = 3 OmV = 200
20 logio 200 = 46dB
S/N ratio = Es(dB) — En(dB) = —7 —(—53) =46dB
REMARKS
Bias current
Equipment:
*VTVM
* Oscilloscope
1. Test equipment connection is shown below
TPL{L-CH)
TP2{R-CH)
Record mode
R5(L-CH)
R6(R-CH)
VTVM Oscilloscope
Fig. 12
2. Place UNIT into record mode, and bias selector to “LOW”.
3. Read voltage on VTVM and calculate bias current by following for-
mula:
Value read on VTVM (V)
10 (Q)
Bias current (A) =
rl
Standard value:
! 500! fea%A (LOW position) |
600 + 290#A
—150uA (HIGH position)
4. Adjust L3 (L-CH) and L4 (R-CH) (See adjustment part location on
page 12)
5. Then changing the bias selector to “HIGH”, confirm that bias current
become greater by 25% than that for normal.
* Record mode
* Be sure the ground end of
the meter is connected to
the ground end of the
resistor.
* When bias current is the
adjusted on one channel
only, note that bias current
on the other channel may
vary
* When L3 or L4 is the
replaced, preset core
position to bottom side of
coil and then readjust
optimum bias current.
Erase current
Equipment:
*VTVM
* Oscilloscope
* Resistor (0.19)
|
1
1. Connect 0.12 resistor between ground side terminal of erase head
ground lead wire removed (See fig. 14).
2. Connect VTVM to both ends of 0.1 resistor
Erase head
Record mode
VTVM Oscilloscope
Fig. 13
3. Place UNIT into record mode, and measure voltage across the 0.122
resistor.
4. Determine erase current with the following formula:
Erase current (A) =
| Standard value: |
100£40mA (LOW position)
| 120450 mA (HIGH position)
+ Record mode
Erase head
Fig. 14

ITEM
Overall gain
Equipment:
* AF oscillator
* VTVM
* ATT
* Oscilloscope
* Test tape
(reference biank tape)
C-RA for Normal
Level meter
Equipment :
* VTVM
* Oscilloscope
* AF oscillator
* ATT
MEASUREMENT & ADJUSTMENT
1. Test equipment connection is shown in fig. 15.
Record mode
LINE IN
AF oscillator
Test tape
R/P head
Playback mode VTVM Oscilloscope
Test tape
Fig. 15
. Place UNIT into record mode, and equalizer selector to 1204S, bias
selector to LOW (for normal tape).
Supply 1 kHz signal (—24dB) from AF oscillator, through ATT, to
LINE IN.
. Adjust ATT until monitor level at LINE OUT becomes 0.42 V (—7 dB).
. Using test tape (C-RA), make recording
. Playback recorded tape, and make sure the value at LINE OUT on
VTVM becomes 0.42 V.
If measured value is not 0.42 V, adjust VR5 (L-CH), VR6 (R-CH) (See
fig. 20 on page 12).
. Repeat from step (2).
1. Supply 1kHz signal (~24dB) from AF oscillator, through ATT, to
LINE IN jack.
2. Place UNIT into record mode.
3. Adjust ATT until monitor level at LINE OUT becomes 0.42 V,
4. Short or open the connection point {D) and (E) so that VU meter indi-
cates O+ 1 VU (See fig. 19 on page 12).
Overall distortion
Equipment:
* Distortion meter
* AF oscillator
* ATT
* Oscilloscope
* Test tape
(reference blank tape)
C-RA for Normal
C-RF for CrOs
REMARKS
+ Record/playback mode
* Record level contro
«MAX
* Input selector---LINE IN
* Standard input level:
MIC +++ +++ —72+3dB
LINE IN —24+3dB
DIN +++ —362+3dB
* Record mode
1. Test equipment connection is shown in fig. 16.
Ww
LINE IN
R/P head
“ aTT 6002 Record
mode Test tape
LINE OUT
AF oscillator
R/P head
Playback mode
Distortion
meter
Fig. 16
Test tape
Supply 1kHz signal to LINE IN and adjust ATT so that output level
at LINE OUT indicates 0.42 V (— 7 dB).
Make recording.
Playback and measure distortion factor of output signal.
* Record level control
--- MAX
* input selector---LINE IN