Pioneer RT-707 User manual

3-MOTOR 4-HEAD TAPE DECK
RT-707
SERVICE
MANUAL
WMPIONEER

MODEL RT-707 COMES IN TWO VERSIONS DISTINGUISHED AS FOLLOWS:
RT-707
r T >
Type
|
Voltage
Remarks
KU | 120V only U.S.A. model
Kc
120V
only
Canada
mode!
CONTENTS
1.
SPECIFICATIONS
........
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2. CONNECTION DIAGRAM ......... 0. cece cece cece cece eee e eee e ee eeneeeeee 4
3.
FRONT
PANEL
FACILITIES
.......
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5
4.
BLOCK
DIAGRAM
.....
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7
5. LEVEL DIAGRAM .... 0... ccc ete eee e eee eeeeeneeeeees 9
6.
CIRCUIT
DESCRIPTIONS
6:1! “Power Supply ses ccs ean ie eames Shei 2S ends Ae dae oh aaeee oeteasten 10
6.2
Control
Circuit
10
6.3 Direction Switch Circuit .... 2.2... ccc cee eee e eens 13
6.4 Switching Circuit, Muting Circuit... 2.2... 6. cece eee tee eee 14
6.5 Playback Amplifier... 2.2.0.6... cece cece cece eee ee eee eee e eee enee 15
6.6 Bias Oscillator . . 16
6.7. Recording Amplifier 16
6.8
Frequency
Generator
........
6.
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17
7. DISASSEMBLY
TA (BONNE 6.5.5 sci ke Sees ee dace Seis Rea wis We deals Gade aeie sue tek B 21
7.2 Rear Panel .. 21
7.3 Bottom Plate 22
7.4 Front Panel 22
8. PARTS LOCATIONS
8.1
Front
Panel
View
...........
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23
8.2 Front View With Front Panel Removed ............ 00. cece ee cece cece eee 25
8.3. Top View With Bonnet Removed ........ 27
8.4 Bottom View With Bottom Panel Removed 29
8.5) Rear Panel View oieiecc sci6ib aid oboe sia de Relea ele niece 0 a icia eb/6is, aoe valde a wees es 31
9. MECHANICAL ADJUSTMENTS
9.1 Reel Base Height Adjustment ........... 2.0... c cece cece cece cece eeenees 33
9.2: ‘Brake Adjustment: ooo e0.3.3 ic cided cspees cee ees hid eek Sis dee eew eae é 33

10.
11.
12.
13.
14.
9.3. Takeup Torque, Back Tension Adjustment ................. 00: c eee eee 34
9.4
Pinch
Roller
Pressure
Adjustment
35
O15, Pause Adjustments. 24.4 2c.00 25 toed etapa dae ARES eae ayeid weeterd serene ge 36
9.6
Tape
Speed
Adjustment
..............
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36
HEAD ADJUSTMENTS
10.1
Head
Rough
Adjustment
...............-08-
:
vee
37
10.2
Playback
Head
Adjustment
38
10.3
Record
Head
Adjustment
..........0
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38
ELECTRICAL ADJUSTMENTS
11.1.
Playback
Level
Adjustment
2.0.0...
0...
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eneeaes
39
11.2
Playback
Equalizer
Adjustment
39
11.3
Level
Meter
OVU
Adjustment
39
11.4
Dummy
Coil
Adjustment
..........0.
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115
Bias
Trap
Adjustment
......
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11.6
Recording
Bias
Adjustment
.......
40
11.7.
Record/Play
Frequency
Response
41
11.8
Recording
Level
Adjustment
...........0
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EXPEODED
VIEW...
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42
SCHEMATIC DIAGRAMS, P.C. BOARD PATTERNS AND PARTS LIST
13.1. Miscellaneous Parts List .... 2.2.0... e eee e eee ee eee teens 2+. 59
13.2 External Appearance of Transistors, ICs and Circuit Diagrams of IC 60
13.3 Connection Diagram .... 2.0... . cece ce cee eee eee cence nee eeeneenes 61
13.4
Schematic
Diagram
.......
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13.5
Playback
Amplifier
Assembly
(RWF-069)
..........
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65
13.6
Meter
Amplifier
Assembly
(RWX-155).......
71
13.7.
Power
and
Oscillation
Assembly
(RWR-053)
73
13.8
Indicator
Assembly
(RWX-142)
......
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13.9 Fuse Assembly (RWX-141) ....
13.10
Equalizer
Amplifier
Assembly
(RWX-154)
13.11
Head
Amplifier
Assembly
(RWF-070)
...........
0.0
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13.12
Connector
Assembly
L
(RWX-151)
22...
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13.13
Connector
Assembly
R
(RWX-152)
.........
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13.14
Function
Switch
Assembly
(RWS-052)
..........
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13.15
MIC
Amplifier
Assembly
(RWF-065)
..........
0...
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13.16
Control
Assembly
(RWG-070)
.......
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13.17
Servo
Amplifier
Assembly
(RWG-076)
.......
13.18
Switch
Assembly
(RWS-058....
.
KC
type)
(RWS-059.....
KU
type)
PACKING)
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106

1. SPECIFICATIONS
Type acchanes op Bass 4-track, 2-channel stereo tape deck
(Recording, playback with reverse
playback)
. Solenoid drive, Pushbutton direct
change system, Timer can be set for
recording and playback.
HeadSis asters toate e Recording Head ; 1
Erase Heads ; 1
Forward playback Head ; 1
Reverse playback Heai
Motors... 02.22.0005 Capstan drive moto
(FG-system, AC servo, direct drive)
Reel base drive motors ; 2
(6-pole inner rotor induction type)
Acceptable Reel Size . Tin (17m)
Tape Speed 19cm/s (7-1/2ips), 9.Scm/s (3-3/4ips)
40.5%
Less than 100 sec. with 7-inch
reel and 370m tape
Wow and Flutter... .. . . Less than 0.05% WRMS (19cm/s)
Less
than
0.08%
WRMS
(9.5cm/s)
More than 58dB
Fast Forward/Rewind Times ... .
Signal-to-Noise Ratio.
Total
Harmonic
Distortion...
..
.
Less
than
1%
(19cm/s)
Frequency
Response
i
eee
eerie
weir
20Hz
to
28,000Hz
(30Hz
to
24,000Hz
+3dB)
SSM:
5 kis
toast
20Hz
to
20,000Hz
(30Hz
to
16,000Hz
+34B)
ome
More
than
S0dB
Channel
Separation.
.
More
than
S0dB
Erasure
Rate
.
More
than
704B
Recording
Bias
Frequency
.
.
125kHz
Equalization.
.........
NAB
Standards
Inputs
(Sensitivity/Maximum
allowable
level/Input
impedance)
MIC;
0.25mV/125mV/27k2,
6mm
diam.
jacks
(suitable
microphone,
2502
to
30k22)
LINE;
50mV/25V/100k2,
DIN;
16mV/8V/1.3k22,
DIN
standards
Outputs
(Reference
level/Maximum
level/Load
impedance)
LINE;
450mV/700mV/SOk2,
DIN;
450mV,
700mV/50k2,
DIN
standards
HEADPHONES;
70mV/822,
6mm
diam.
jack
Semiconductors.
. .
+
67
transistors
(4
FET’s),
5
IC’s,
47
diodes
(1
thyristor,
2
LED's,
4
Zener
diodes,
2
varistors,
)
Crosstalk
Accessory Functions
©
Pitch
control
(more
than
+6%
of
rated
tape
speed)
@ Auto reverse playback (with sensing tape: manual reverse is
possible)
© Auto repeat (counter-interlocked)
© Recording mode switches (L, R independent)
© Tape selectors: BIAS (STD/LH); EQ (STD/LH)
© MIC/LINE mixing
© Output volume controls
‘© Pause indicator lamp
Power Requirements... . . AC 120V 60Hz
Power Consumption . 120 watts, Max.
AC Outlets,
Dimensions . . . .
. » Unswitched (300W max.) x 1
+ 480(W) x 230(H) x 356(D)mm
18-29/32 x 9-1/16 x 14in
Weight... 22.2.0 000- Without package; 20.0kg 441b loz
With package; 23.5kg 511b 1302
RT-707
Accessories .......... © Tin metal reel (Pioneer PR-85) x 1
Connecting cord with pin plugsx2
Head cleaning kit x 1
Sensing tape x 1
Splicing tape x 1
Operating instructions x 1
NOTE:
Specifications and the design subject to possible modification
without notice due to improvements.

2. CONNECTION DIAGRAM
LINE
output level
controls
I
|
SS
DQUOQUNAON000 00)
QQQA0UI0N00U0U1
Ac OUTLET
MAX MIN
OUTPUT LEVEL
AC OUTLET
This is the power socket (maxi-
mum power capacity: 300W).
You can connect the power plug
on another tape deck or amplifier
to this socket,
These controls can be used to
adjust the LINE output levels.
Turn them clockwise to increase
the levels, They have a center
click position where the standard
output level (450mV with 0dB
displayed on the level meter) of a
standard tape can be obtained.
terminal
To the power
outlet or AC
outlet on the
stereo amplifier
Ground wire
Tape connectors of
RT-707's playback /
the stereo amplifier
recording connectors
TAPE
OUTPUT
INPUT
Connections for
recording a
mol
|
IN/OUT
Left channel
DIN connector
Connections
for
playback
Right
channel
Left channel
REC/PLAY connector
(DIN
standard)
of
sec-
‘ond stereo amplifier
REC/PLAY
001006
¢@670090
Recording/
playback
cord (DIN
standard)

3. FRONT PANEL FACILITIES
POWER SWITCH
Push this switch and power is supplied to the tape deck. Push for a
second time to turn the power off.
SPEED SWITCH -
This switch selects the tape speed. Push for a 9.5cm/s speed; push
again for a 19cm/s speed (released position).
19cm/s: Used for recording music programs, etc.
9,5cm/s: Used for recording lengthy conversations, etc.
PAUSE LAMP:
This green lamp lights up when the PAUSE button is pressed to
indicate the tape has stopped temporarily.
PHONES JACK
This is the output jack for stereo headphones. Signals selected by
the MONITOR switch are available here. Use it when you want to
monitor the recording or listen to a performance directly taped
from the RT-707. The output level is not variable.
MIC JACKS €)
These
are
the
input
jacks
for
microphone
recording.
The
L
(left)
and
R
(right)
channels
can
be
used
independently.
Only
the
micro-
phones’
input
signals
are
recorded
if
the
REC/PLAY
connector
(DIN
specifications)
on
the
rear
panel
and
the
MIC
jacks
are
connected
at
the
same
time,
As
long
as
the
microphones
have
a
standard
6mm
diameter
plug,
you
can
use
either
a
low
impedance
(600-ohms)
or high impedance
(10 — SOkohms)
type.
MIC
RECORDING
LEVEL
CONTROLS
Use
these
controls
to
adjust
the
recording
level
when
you
are
recording
with
a
microphone
(or
microphones)
or
when
you
are
using the rear panel REC/PLAY
comnector
(DIN standard).
Use
the
outer
control
for
the
right
and
the
inner
control
for
the
left
channel.
Input
signals
from
both
the
MIC
jacks
and
the
REC/PLAY
connector
cannot
be
recorded
simultaneously.
LINE RECORDING LEVEL CONTROLS
Adjust the recording input level from the LINE INPUT terminals
‘on the rear panel. The level increases as the controls are turned to
the
right.
The
outer
control
is
for the
right
channel
and
the
inner,
for the left.
RECORDING LAMP (REC)
This red lamp lights up during recording. Check that it has lit up
before recording.
MONITOR SWITCH
Use this switch to monitor your recording.
TAPE: Allows you to listen to the recorded signals.
SOURCE: You can listen to the signals before recording if this
position is selected (press switch once).
If this switch is switched alternately to SOURCE and TAPE during
recording, you can compare the sound signals beforé and after
recording.
BIAS SWITCH
This
selects
the
recording
bias
current
according
to
the
type
of
tape
used
for
recording.
Push
for
LH
tapes;
push
again
for
STD
tapes (released position).
STD:
For
standard
tapes.
LH:
For
low
noise
and
high
output
tapes.
EQ SWITCH
This
selects
the
recording
equalization
characteristics
according
to
the
type
of
tape
used.
Select
same
position
for
playback
as
for
recording
according
to
the
characteristics
of
the
recording
tape.
Push for LH; push again for STD (released).
STD: For standard tapes.
1H: — For low noise and high output tapes.
TAPE COUNTER
This indicates how much tape has been recorded or played back
and how much there is left over.
REPEAT BUTTON
This button allows you to reverse the tape forward for reverse
playback automatically. If you remember to worrk the tape
counter and REPEAT button, then the tape will automatically be
reversed and the tape deck will be set to forward playback when
the “0000” display on the tape counter gives way to "9999"
during reverse playback. Be sure to release this button when you
do not require repeated playback.
COUNTER RESET BUTTON
Push this button to reset the tape counter to “0000"
LEVEL METERS
These allow you to read out the levels during recording and play-
back. When the MONITOR switch is set to SOURCE, they
indicate the input signal level, and when set to TAPE, they
indicate the playback output level.
APSTAN
This rotates when the power is switched on, Together with the
pinch roller, it keeps the tape at its rated speed.
PITCH CONTROL KNOB
You can use this to make the tape travel 6% faster or slower than
the normal tape speed during playback. When set to the central
position, the tape speed is 19cm/s or 9.5cm/s (standard values).
Turn the control to the left and the speed drops and the musical
steps are lowered; conversely, turn it to the right, and the speed
rises and the musical steps are raised. This control cannot be used
during recording.
RT-707
REC MODE SWITCHES (L. R)
Depress
these
switches
when
recording.
L: Use this switch for L (left) channel recording.
R: Use this switch for R (right) channel recording.
For stereo recording, make sure that you depress both switches.
7 TAPE DIRECTION SELECTOR BUTTONS
These buttons allow you to select the direction of tape play during
playback. When depressed, the button’s lamp will light up to
indicate the direction of tape play.
Forward playback: The tape runs from left to right.
Reverse playback: The tape runs from right to left.
When you are recording, you cannot change the direction of tape
play even by depressing this button. The tape will always run ina
forward direction.
PAUSE BUTTON
This
temporarily
stops
the
tape
during
tape
play.
When
pressed
during
recording
or
playback,
the
tape
merely
stops.
When
pressed
again,
the
tape
starts
to
run.
This
button
does
not
work
during
fast forward or rewind.
FUNCTION BUTTONS
44 REWIND: This cause the tape to be wound at a high speed
from the right to the left reel.
>P FAST FORWARD: This causes the tape to be wound at a
high speed from the left to the right reel.
PLAY: For tape playback, or recording, push this button.
REC: To record, press this button together with the PLAY
button.
@™ STOP: This stops the tape and releases the other function
buttons.
NOTE:
© The function buttons will not return to their preset positions
if the power is turned off.
© The tape will always run in a forward direction when the
POWER switch is depressed to the ON position.
© If you depress both the PLAY and REC buttons with the
tape set to the reverse playback direction, then the tape will
sometimes move slightly backwards and then start to run
forwards. Therefore, when recording, make sure that you set
the DIRECTION button to the forward playback position.
© There is no need to press the (j™) stop button if you want
to change over from one function to another.

4. BLOCK DIAGRAM
HEADPHONE Amp.
METER DRIVE Amp.
PB. HEAD >
(FWwO)
NOTE:
The
number
which
are
circled
in
the
block
diagram
indicated
the
points
which
are
to
be
measured
in
the
level
diagram.
@
HEAD
PHONES
ca
LINE OUTPUT
o]
MIC INPUT
DIN
LINE
INPUT
i
©
CONTROL Ass'y
INDICATOR
a
ig
5
Ped
0
|
|
Su
Si2|
gp.
ac
‘“
Su-3
a
s
baa
io Sto q™ Seg
foe ee
AC 120V
CF sO Hz
SWITCHES
St
Se
S3
Sa
Se
St
Se
Sa
Sis
Se:
: POWER
: SPEED
+ MONITOR
= BIAS
Ss:
E.G
RECORD LEFT
» RECORD RIGHT
: REW
: FWD
Sto =
Sit
Sr:
Sa:
Su:
PLAY
REC
PAUSE
Fwo
REVERSE
REPEAT
SHUT OFF
RELAIES
RY301 :
RY202 :
RY en
RY
oz
:
LAMPS
Pu
Plz:
Pla:
Pla:
REC LEFT
REC RIGHT
:
PLAY
DIRECTION
: LEVEL METER LEFT
LEVEL METER RIGHT
FwD INDICATOR
REVERSE \NDICATOR

RT-707
5. LEVEL DIAGRAM
NOTES:
OdBu=1V
Frequency: 1kHz
(PLAYBACK)
The
level
measurement
points
are
indicated
on
the
block
diagram.
dBy
a4
©
vaby
©
-7aBv
@-1468v
-2074
LEVEL
- 60
(RECORDING }
©-10aBv
-20dBv
20
(© -3048
-30
@
}OdBv
@-a1aBv
-40
® -46dBv
LEVEL
~90

6. CIRCUIT DESCRIPTIONS
The block diagram is shown on page 7.
Model RT-707 is an open reel tape deck charac-
terized by direct drive 4-track 2-channel configu-
ration, 3 motors, 4 heads autoreverse
The sensor touch pushbuttons used in most 3-
motor tape decks necessitate a relatively large num-
ber Of relays in the transport control electronics;
the RT-707, however, uses locking type pushbut-
tons which permit simplified circuit construction
and also facilitate automatic unattended recording
in conjunction with a timer.
6.1 POWER SUPPLY
When the power switch S, is switched on, AC100V
is supplied to the capstan motor from the secon-
dary side of the power transformer, and the motor
begins to rotate. A DC voltage rectified in Dgo,
D4o2, stabilized in the stabilizer formed by Q4o1,
Q4o2 and ZD4o,, is supplied to the control circuit
(Fig. 1).
6.2 CONTROL CIRCUIT
The control circuit is shown in Fig. 2. Table 1
indicates the transistor states for the different
transport modes.
@ Play Function (Fig. 2)
1.
When
the
play
button
S,0-,
is
pushed,
ground
connection
of
R497
is interrupted
and
the
base
circuit
of
Q4o,
is opened.
No
current
can
flow
through
Q4o4,
and
it enters
OFF
state.
2.
+B
voltage
causes
current
to
flow
along
the
route
Daos > Qaog > R413 > Raio,
whereby
Qao5
is turned
ON.
3.
As
R47
is
connected
between
base
and
emitter
of
Qos,
this
transistor
is
turned
ON.
The
collector
current
of
Qu4o9
activates
brake
solenoid
SL,,
pinch
solenoid
SL,
and
play
relay
RY...
4.
+B
current
also
flows
along
path
Dao;
>
Qyos
>
Rai
>Raio,
whereby
Q4o;
becomes
ON.
5.
As
Rais
is
connected
between
base
and
emitter
of
Q4i0
,
base
current
can
flow
and
the
tran-
sistor
becomes
ON.
Q4io
collector
current
activates
PAUSE
solenoid
SL;.
Operation
of
brake
solenoid
SL,
releases
the
brakes
of
the
supply
motor
(SM)
and
take-up
motor
(TM).
Operation
of
the
pinch
solenoid
SL,
causes
the
pinch
roller
ta
be
pressed
against
the
capstan.
Operation
of
the
play
relay
RY¢o;
enables
AC
70V
from
the
secondary
side
of
the
power
transformer
(see
Fig.
1)
to
be
applied
to
the
supply
and
take-up
motors
through
slide
resistors
R,
and
R;.
Power
switch
}
Si
|
ACI20V -~ ?
60Hz
;
a
Ry6o1-2 ~ a
10
Fig. 1

@ Rewind (& Fast Forward) Function (Fig. 2)
1.
When the rewind button S3_-; is pushed, +B cur-
rent flows along the path brake solenoid SL, >
Dao7 > Ss-3, and SL, operates, releasing the
supply and take-up reel brakes.
As shown in Fig. 1, AC100V is applied to the
supply motor via F.F. button S,., and Rewind
button S,-, , and tape rewind begins.
. AC100V also flows to the take-up motor via
F.F. button S,., > rewind button S,., > slide
resistor R, > play relay RY¢o, . The slide resis-
tor serves to apply the proper amount of back
tension to the take-up motor in rewind mode.
. In F.F. mode, on the other hand, AC100V
from the secondary side of the power trans-
former is applied to the take-up motor through
F.F. button So.,.
AC100V also flows to the supply motor via
the route formed by S,.; > play relay RY¢o: >
slide resistor R,. The slide resistor serves to
apply the proper amount of back tension to
the supply motor in fast forward mode.
RT-707
© Solenoid Voltage Control Circuit (Fig. 2)
When transport functions are switched, operating
current of the solenoids must be temporarily in-
creased to effect the switching action, but current
must be reduced again immediately to avoid over-
heating of the solenoids.
1. When, for example, the play button is pushed,
a surge of charge current (base current from
Q407) flows to Caog, and Qao7 is turned ON.
2. Brake solenoid SL,, pinch solenoid SL,, play
relay RY go, and pause solenoid SL; are con-
nected as loads to Q4o3. As explained under
PLAY FUNCTION, above, these solenoids
operate in play mode, whereby the Q4o7 emit-
ter current becomes the Q4os base current,
turning Q4o3 ON.
8. As soon as C4og has been charged, bias of Qso7
returns to the normal operating value deter-
mined by stabilization in Rais;, ZDao2-
Table 1
| Transport Mode Transistors in ON state Transistors in OFF state
| STOP Q4o4 Q403, Q405+ Qa06, Qa09s Qaro
PLAY Q403, Qaos, Qa06, Q409, Qaio_| Qaoa
FF/REW Qaos Q4031 Q4051 Qa06 Qao9» Qaio
PAUSE Qaos; Qaos, Qaoss Qsi0 Qsoa, Qso9
Capstan Motor
Solenoid
use Solencid
Sle : Pir
RY¢o1: Play Relay
59.3 510-2 cal t
Fig. 2
44