Pioneer PL-707 User manual

Service
c/Manual
CIRCUIT & MECHANISM ——
DESCRIPTIONS in
. RDER NO.
REPAIR & ADJUSTMENTS RHP 2 56-0
STEREO TURNTABLE
L-70O7
MODEL
PL-707
COMES
IN
FOUR
VERSIONS
DISTINGUISHED
AS
FOLLOWS:
K
AC120V only U.S.A. model (Without cartridge)
AC220V, 240V (switchable) United Kingdom model
AC110V, 120V, 220V, 240V (switchable) General export model
| He AC220V, 240V (switchable) European continent model
@
This
service
manual
is
applicable
to
the
KUT
type.
For
servicing
of
the
other
types,
please
refer
to
page
56.
©
Ce
manuel d’instruction
se
refére
au
mode
de
réglage,
en
francais.
@
Este
manual
de
servicio
traat
del
método
de
ajuste
escrito
en
espajiol.
CONTENTS
1. SPECIFICATIONS .......... 00000 c ee eee 2 10. P.C. BOARDS CONNECTION DIAGRAM .... 36
2. FRONT PANEL FACILITIES............. 3 11. SCHEMATIC DIAGRAM .............05- 39
3. BLOCK DIAGRAM ...............0005 5 12. ELECTRICAL PARTS LIST.............. 42
4. MECHANISM DESCRIPTION ...........-. 7 13. TROUBLESHOOTING ............2.000. 44
5. CIRCUIT DESCRIPTIONS ............... 13 14. ADJUSTMENTS .............0 ccc e eee 50
6. DISASSEMBLY ...........0..000eeeeee 23 REGLAGE 42d catia ena ed Seaawes 52
7. PARTS LOCATION ........0. 00 cee eeee 27 BIUSTE: vc Son ed eo wh Oo cary aa eas 54
8. EXPLODED VIEW AND PARTS LIST...... 29 15. FOR HE,HB AND S TYPES oo. - cece eee 56
SB: PACKING |G. cask ob ore best os Sue wes 35 16. SAFETY INFORMATION .............-- 58
PIONEER ELECTRONIC CORPORATION 4-1, Meguro 1-Chome, Meguro-ku, Tokyo 153, Japan
PIONEER ELECTRONICS (USA) INC. 1925 E. Dominguez St., Long Beach, California 90810 U.S.A.
PIONEER ELECTRONIC (EUROPE) N.V. Keetbergiasn 1,2740 Beveren, Belgium
PIONEER ELECTRONICS AUSTRALIA PTY. LTD. 178-184 Boundary Road, Braeside, Victoria 3195, Australia
FZ © APR. 1983 Printed in Japan 9) ’

1. SPECIFICATIONS
Motor and Turntable
Drive System .0......ccceece neces een seeeeseeceeeeeeseees Direct-drive
Motor . Quartz PLL Hail motor
Turntable Platter ........ 310 mm diam. aluminum alloy die-cast
Speeds 33-1/3 and 45 rpm
Wow and Flutter .. Less than *0.012% (WRMS)
0.025% (WRMS)
+ 0.035% WTD Peak (DIN)
Values marked with an ‘’*” designate the wow and flutter for
motor, and do not include the cartridge or tonearm load.
Signat-to-Noise-Ratio ..............06 More than 80 dB (DIN-B)
(with Pioneer cartridge model PC-6MC)
Tonearm
NY PO: iar iiceeesanstcesetees Static-balance type, Straight pipe arm
Effective Arm Length -. 235 mm
OVEINANG iiss siicasccsceecatats conned decsuceseetbenavevdesees 15mm
Usable Cartridge Weight ... 3g (min.) to 8 g (max.}
PC-6MC Specifications
Type ... Moving coil type
Stylus... 0.3x0. 7m mil diamond (PN-6 MC)
Output Voltage oo. cee eceeeessanenneeneasanasaeeees 2.2mVv
(1 kHz, § cm/s LAT. Peak)
Tracking Force ..........02..-2...c0eeee ee 1.7 g to 2.3 g (proper 2g}
Frequency Response
Recommended Load ..
Weight
+ 10 to 35,000 Hz
- 50kQ
Subfunctions
Auto lead in, Auto return, Auto cut, Repeat, Quick play, Quick
stop, Anti-skating, Arm elevation, Tracking-force direct-read-
out, Tonearm height adjusting device (+ 3 mm}, Insulator
height adjusting device, Free stop hinges.
Miscellaneous
Power Requirements
HE, HB, HP models .20....... cc. eesceeenesee eee AC 220 V/240 V
(switchable), 50, 60 Hz
KUT, KCT models AC 120 V, 60 Hz
S,S/G models ................4 AC 110 V/120 V/220 V/240 V
(switchable), 50, 60 Hz
Power Consumption
HE, HB, HP models . OW
KUT, KCT models . 10W
S, S/G models .... a. 7W
Dimensions ...........c:0ccceeeees 460 (W) x 164 (H) x 409 (D) mm
18-1/8 (W) x 6-1/2 (H) x 16-1/8 (D) in.
WIGKt oie. cseediccueetestiagesseucesibandestesecess 8.1 kg/17 Ib 14 oz
Accessories
EP Adapter .. psveelaceniviseee Macetisaentccatoned
Operating instructions tee baal,
Catridge mounting parts (For KUT and KCT models)
Serews: (IL): G%e5 at aoe iyo, Deeg aeh o hace Gu cea 2
Screws: (M)) 4 pis Tak GATE Saw eee wae edd ee ae 2
Screws (S) isco ek aS whe ba ed ok Sew Seale 2
Washers ss \hiciss ce gow s Rieriiede'e Kegele oe ee 2
NUS chic oe casas uepehare OA on eormeban nna 2 2
NOTE:
Specifications and design subject to possible modification without
- notice, due to improvements.

2. FRONT PANEL FACILITIES
@ POWER SWITCH
Press this switch to turn the power on and off.
{ON} (depressed position) : Power is switched ON.
{OFF] {released position) : Power is switched OFF.
When the POWER switch is set to ON, the following swit-
ches are set automatically.
¢ SPEED switch — [33]
¢ RECORD SIZE switch — [30]
© REPEAT switch — [OFF]
=) (eS)
©
~y
2 @)
«
ae
@ SPEED SWITCH
Set this switch in accordance with the speed of the record
which is to be played.
[33] indicator lights:
For playing 33-1/3 rpm records.
[45] indicator lights:
For playing 45 rpm records.
@ RECORD SIZE SWITCH
Set this switch in accordance with the size of the record
which is to be played.
[12°30] indicator lights:
For playing 30 cm (12”} records.
[10°25] indicator lights:
For playing 25 cm (10°) records.
[7°17] indicator lights:
For playing 17 cm (7”) records.
@ REPEAT SWITCH
Press this switch so that the indicator lights for repeat play.
@ ARM ELEVATION SWITCH
¢ Use the switch to manual play.
* Use the switch to suspend record play temporarily.
© Use the switch when changing the tracks during manual
play.
{ ¥ ] indicator tights:
The tonearm rises (the styius moves away from the record).
l & | indicator lights:
The tonearm descends (the stylus is lowered onto the
record).
@®© START/STOP SWITCH
Press this switch when starting auto play or when stopping
play
@ QUARTZ LOCK INDICATOR
This lights when the platter is rotating at exactly 33-1/3 or 45
revolutions per minute.
SPEED INDICATORS (33, 45)
These indicate the platter speed.
(33] lights:
Platter is rotating at 33-1/3 rpm.
[45] lights:
Platter is rotating at 45 rpm.
@® SIZE INDICATORS (30, 25, 17)
These indicate the record size.
{1230} lights — 30 cm (12)
(10°25] lights — 25 cm (10)
[7°17] lights — 17 cm (7”)
REPEAT INDICATOR (REPEAT)
This indicator lights up when the repeat play function is
utilized.
@ ARM ELEVATION INDICATOR ( ¥-¥ )
These indicators indicate whether the tonearm is the raised
(up) or jowered (down) position.
( ¥ J lights:
The tonearm rises (the stylus moves away from the record}.
[ & } lights:
The tonearm descends (the stylus is lowered onto the
record).
@ START/STOP INDICATOR
This lights when the START/STOP switch has been
pressed and auto piay has been started.
© This lights when the START/STOP switch is pressed to
suspend play.
@ CARTRIDGE (PC-6MC)
NOTE:
A cartridge is not provided with the KUT and KCT models and so
your own cartridge should be mounted, following the instructions
laid down in CARTRIDGE MOUNTING.
@ HEADSHELL
@® ANTI-SKATE CONTROL
This is rotated when performing the anti-skating adjustment.
ARM REST
This serves to hold and clamp the tonearm. When moving
the tonearm, release the clamp.
@ TONEARM
TRACKING FORCE ADJUSTMENT
WEIGHT
This is used when adjusting the tracking force.
PLATTER
PLATTER SHAFT
@ RUBBER MAT
@ EP ADAPTER
This is used when playing records without a “middle.”
@ CABINET
@ DUST COVER

3. BLOCK DIAGRAM
PHONO MOTOR CONTROL SECTION
WAVEFORMS ING THRU @ ARE PARSED THROUGH
SUFFER Aue,
Al1C1 PA2007 &21C2 PA2008
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Let
APHASE
LB2
.
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) Lat
Lae
*
7’
zav
"AIC 4 TD62503P!
. 2:
STANDARD STANDARD 332¢rpm—-55. Hz 45-om—~75Hz: (QUARTZ LOCK SIGNAL tovces | MOTOR Con
r 33/45
GENERATOR $A1C« TOCTS03P syle asi (QUARTZ LOCK SIGNA’
33/45,
STOP SIGNAL’
TONEARM SENSOR SECTION CONTROL SECTION TONEARM MOTOR DRIVE SECTION
B: IC: PD6003 B:IC2 BAs208
ClICl
TCADIBP
POSITION SENSOR
PHONO 8
Swt MOTOR
stop
TONEARM
DRIVE MOTOR
oe aia | QUARTZ
LOCK IND
@:04 |
sv iy as ino
POWER SUPPLY SECTION CONTROL SWITCH SECTION * ; |
B:1C3 r soem
uPCTBMOSH IND
G: 55: SPEED ae 25em IND
288: | sw is "
dee Vem
1 S40 SiZE
6 sw ae Hem IND
—. REP
H:S6: REP REP sw IND REPEAT IND
— |
HOS? EV Ev Sw uP IND DOWN IND
~—7 |
15 START/ STAAT/ 5
C * : START/STOP STOP STOP uP IND
Laced sw IND
POWER TRANSFORMER
START/STOP
IND
SWITCH
St: Mtcro ON: OFF S7 ARM ELEVATION UP--OOWN NOTE
pease
Aas
Gee
Bie
erantseTor
ON-OFF
‘The
jtters
preceding
the
circuit
component
symbols
denote
the
unit
s — — where the component is located.
2 POWER OFF
$3:
PO
ON
OFF
A:
MOTOR
ASS‘Y
(PXM-175)
F.
ORIVER
(F}
ASS'Y
Sa:
SIZE
30cm
25m
-
Tew
‘The
uncerlined
rndicates
the
switch
position.
B
CONTROL
UNIT
(xwM.141)
G:
CONTROL
(A)
UNIT
6
epee
33410
asrpm
C:
PHOTO-TRANSISTOR
UNIT
(xwx-137)
{XWX-134)
O: LED UNIT (xwx.1381 H: CONTROL (8) UNIT
EPEAT ON OFF
S6
:
AEPE,
OFF
E
START
UNIT
(XWX-1361
(xwo-138)

PL-707
4. MECHANISM DESCRIPTION
To facilitate understanding the operation of the
PL-9, the total unit may be broken down into
blocks consisting of the tonearm drive mechanism,
the sensing mechanism serving to sense lead in and
lead out positions of the tonearm, the control
section consisting of the full-auto control IC
PD6003, and the motor section functioning to
drive the turntable platter. >»
Trip wheel
Switch SW1
« The operational and functional relationship
between each block is quite complex, so in order
to understand total system operation, it is first
necessary to thoroughly understand the operat-
ion and function of each block, then carefully
study their interrelationships.
This manual covers the subject in that order.
First, the operation and function of each block
will be described, then a timing chart is presented
to clarify block relationships.
Cam (Sloping area)
Worm-gear
Fig. 4-1 Tonearm drive mechanism
4.1 TONEARM DRIVE MECHANISM
1. The tonearm drive mechanism consists of the
tonearm drive motor, worm-gear, gear (A),
gear (B), trip gear, trip wheel, cam, switch SW1,
and switch SW2. (Fig. 4-1)
2. The gear cluster is shown in Fig. 4-2. When the
cam is held immoveable and gear (A) is rotated
in a counterclockwise direction, asmall amount
of friction is felt, but gear (B) and trip gear
also rotate. Note that rotation of the trip
gear also rotates the trip wheel. (Fig. 4-3)
Also note that when the cam is free to rotate,
friction will cause it to rotate in the same
direction as gear (A) and (B).
8. Refer to Fig. 44. The elevation shaft contacts
the sloping area located around the center
shaft of the cam. Also note the position of
the cam at this time. This is the position the
mechanism will be in prior to starting up the
unit. The tonearm will be on the arm rest,
and arm-elevation will be in the DOWN posit-
ion.
Center shaft Trip wheel
Friction plate
2 ae
Gear (A) i
Aisin
ai
omy
y
Fig. 4-2 Gear cluster
Trip wheel
YW
Prevent the cam from
F /
{uring
Fig. 4-3 Gear cluster operation

PL-707
Elevation shaft
Sloping area
Cam
Tonearm shaft
Fig. 4-4 Lead in operation
Sloping area _|
<p
Elevation shaft
Tonearm shaft
Trip wheel \
Trip gear
Fig. 4-5 Return operation
4. Turn the worm gear by hand imitating what
would occur if the START/STOP button were
depressed causing the motor to rotate the gear.
Worm gear rotation causes gear (A) to rotate,
and the gears shown in Fig. 4-2 and 4-3 of item
2 above all turn in a clockwise direction.
5. The elevation shaft raises as the gear/cam
assembly rotates, and this in turn causes the
tonearm to raise. The two switches, SW2
and SW1 are also tumed OFF.
6. As the assembly rotates further, the trip wheel
and PU plate attached ‘to the tonearm shaft
come into contact, creating the same condition
as occurred in item 2 where the cam was
held in an immoveable position. Continued
rotation of the trip wheel causes the PU plate
attached to the tonearm shaft to tum.
7. Rotation of the PU plate moves the tonearm
to the point specified by the sensing and
control mechanisms (covered in the following
paragraphs). When the tonearm reaches that
specified point, the motor reverses itself, and
the cam switches SW1 and SW2 ON in
sequence. Arm-elevation goes to the DOWN
position and playback starts.
8. In practice, each of the above operational
steps are controlled either directly or indirectly
from the control section or by the forward or
reverse rotation of the motor. The control
section picks up its operational cues by detect-
ing the ON or OFF status of switch SW1 and
SW2, and these switches are controlled by the
movement of the mechanism positioning the
cam.
4.2 SENSING MECHANISM
As shown in Fig. 4-6, the shutter fixed to the
tonearm is positioned to travel in the space be-
tween the phototransistors and LEDs mounted on
Phototransistor board
Phototransistor
>
S > End sensor (A), (B)
ais Lowering position detector
Shutter
Fig. 4-6 Sensing mechanism
their respective boards. The shutter has three
0.7mm slits cut out of its outer circumference
at the position the outer edge of a 30cm, 25cm, or
17cm record disc would be located. The slit, or
opening located inside of those three slits is the
end sensor slit (Fig. 4-7).
Stit (30 cm)
Slit (25 em)
End sensor slit
Fig 4-7 Shutter
= Lowering Position Detector
1. This unit is mechanically designed to allow the
shutter to pass between two boards mounting
the sensing elements or photocoupler. The
photocoupler consists of an LED and photo-
transistor.
2. The shutter moves with the tonearm, and a
signal is transmitted to the control section
by the light emitted from the LED (normally
interrupted by the opaque portion of the
shutter) being passed through the 30cm,
25cm, or 17cm slit and triggering the pho-
totransistor ON.
Function
End Sensor
As the tonearm travels toward the inside of
the record disc and reaches the end sensor
zone (end sensor slit), the light transmitted
by the LED is passed through the end sensor
slit and turns the phototransistor ON, then
OFF. This causes the pulse signal transmitted
by end sensor A and B to go 90° out of phase.
2. The pulse frequency is compared with the
rotational speed (movement) of the tonearm,
and then sent to the control section as the re-
cord disc lead-out groove sensor signal.
i
Arm Rest Position Sensor
When the three sensors consisting of the lower-
ing position sensor and end sensor (A) and
(B) are all simultaneously picking up transmit-
ted light, control determines that the tonearm
is at the arm rest position.
2. This status is used to control starting and
stopping of the turntable motor during manual
operations, or, in the auto-return mode, simply
perceives that the tonearm has returned to the
arm rest.
He
Function
Repeat display output
CW rotation output
{EV-UP display output
START-STOP display output SW2 input
Speed selector output
Turntable motor stop output
Ryo
. |30cm display output
25cm display output
Size selector switch input
R. : |17em display output
End sensor B input
End sensor A input
R, [Repeat switch input
Lowering position sensor input!
T
R, | EV switch input
22
R. | START-STOP switch input
{
|
‘
i
R, R. |Speed selector switch input
tC PD6003 pins
R, R. | CCW rotation output
PD6003 Pin Function Table
Fig. 4-8 PD6003

; PL-707
4.3 CONTROL SECTION
The functions of the full-auto control IC
PD6003 are described in this section. The table
shown in Fig. 4-8 lists the function performed
by
each pin of PD6003. Please refer to this table
as the detailed explanation progresses.
1.
When the tonearm is at the arm rest position,
pressing the START/STOP button causes the
turntable motor to start rotating and illumin-
ates the LED built into the START/STOP
button and the EV UP display LED. At the
same time the tonearm drive motor moves the
tonearm toward the lead in groove of the
record.
The tonearm drive motor continues rotating
until it reaches the point where the signal from
the lowering position sensor is picked up.
When that point is reached, the drive motor is
reversed, lowering the tonearm.
End sensor A and B is used to detect the end of
playback, but if the START/STOP button is
depressed during playback, the tonearm drive
motor starts rotating in the return direction
and tonearm returm operation is started. When
the tonearm reaches the point directly above
the arm rest, the tonearm drive motor starts
rotating in the reverse direction and lowers the
tonearm on the arm rest.
If the operation in the above step is carried out
with the repeat switch ON, the tonearm again
will returm to the lead in groove. If the repeat
switch is OFF, the tumtable motor will stop at
this point.
4.4 ACTUAL OPERATION (PLAYBACK OF A
1.
2.
10
33 rpm, 17cm RECORD DISC)
Automatic Lead in
Depress the button and turn the power switch
ON. Set the speed for the record to be played
(33 rpm). When the 33 rpm button is depressed,
an instruction signal from the motor assembly
will illuminate the 33 rpm display LED, D22.
Next, set the proper size for the record to be
played (17cm in this case). When the size
selector switch is depressed twice, the 11 pin
of PD6003 will go to a low level, and the 17cm
display LED, D26 will be illuminated.
With the turntable thus set up, depressing the
START/STOP button causes the 15 pin of
PD6003 to go to a low level. Also 6 pin
goes to a low level, illuminating the START/
STOP display LED, D30. At the same time, pin
17 goes to a low level and pin 18 goes high,
starting rotation of the tonearm drive motor
in the mechanism section.
The worm gear is coupled to the rotating
motor by belt, and the worm gear turns gear
(A) (and cam) in a clockwise direction. The
tonearm is lifted by the arm-elevation mech-
anism, and switch SW2 and SW1 go OFF.
Gear (A) (and the cam) continue rotating until
finally, the cam makes contact with the PU
plate fixed to the tonearm shaft. When the
cam contacts the PU plate, it stops rotating.
However, the trip wheel continues rotation
along with gear (B).
Fig. 4-9 Mechanism section
The trip wheel is making contact with the arm
rotation stopper, and the rotating trip wheel
causes the PU plate to turn. The tuming PU
plate moves the tonearm toward the center
of the platter.
As the tonearm moves, so does the shutter
attached to the tonearm shaft. The tonearm
(and shutter) go past the 30cm and 25cm
lowering position until it reaches the 17cm
record disc lead-in groove where the third
pulse signal from the lowering position sensor
{light from LED passes through the slit in the
shutter fixed to tonearm shaft turning pho-
totransistor ON) causes the 26 pin of PD6003
to go to a low level. (Pulse signals are also
produced at 30cm and 25cm positions.)
10.
This causes the PD6003 17 pin to go low, and
the 18 pin to go to a high level, and after the
tonearm drive motor stops, it commences
reverse rotation. As it rotates, the arm-elevat-
ion shaft riding on the sloping area of the cam
moves down off the slope and playback starts.
When the tonearm drive motor rotating in re-
verse (switch SW1 ON) tums switch SW2 ON,
the PD6003 6 pin goes to a high level, extin-
guishing the START/STOP display LED, D30.
The tumtable will not go into the auto-stop
until the START/STOP display LED is ex-
tinguished even though the START/STOP
button is depressed. Also, when both the
tonearm dirve motor and switch SW2 are
ON, PD6003 17 and 18 pin both go high,
stopping the drive motor.
If the tonearm does not move off the arm rest
within 8 seconds after the START/STOP
button is depressed (tonearm clamped in arm
rest), the START/STOP display indicator starts
flashing. If this status (flashing) continues for
another 11 seconds, the start instruction is
cancelled and the tonearm lowers in the arm
rest.
The elevation -up display LED, D28 illuminates
when the START/STOP button is depressed,
and when the tonearm moves to the record
disc and lowers down, D14 is extinguished.
PD6003 senses the first pulse as the 30cm
position, the second as the 25cm, and the
third as the 17cm record size position. When
it determines that the tonearm has reached the
proper lowering position, pin 5 goes to a high
level, extinguishing the display.
Switch SW2
Switch SW1
vee
Gear (A)
Fig. 4-10 Switch SW1, 2 position
PL-707
Arm-elevation UP and DOWN
. When the arm-elevation switch is depressed
during record playback, arm-elevation goes UP
and playback is temporarily stopped.
When the arm-elevation switch is depressed,
the 13 pin of PD6003 goes to a low level.
Pin 5 also goes low, and illuminating the
elevation display LED, D28.
At the same time, pin 17 goes to a low level
and pin 18 goes high, starting tonearm drive
motor rotation. This causes the cam to turn,
and the elevation shaft to ride up on the slop-
ing section of the cam. This action causes the
arm-elevation to go to the UP position, stop-
ping record playback. :
The tonearm drive motor continues to move
the cam until the position is reached where
SW1 is turned OFF (tonearm still in UP posit-
ion).
To restart playback, the arm-elevation switch
is depressed again. This causes the 13 pin of
PD6003 to go to a low level. The 5 pin goes
high, extinguishing the elevation display LED,
D14.
At the same time, pin 17 goes high and pin
18 goes low, causing the tonearm drive motor
to rotate in an opposite direction of that in
the UP position. As the cam turns, the elevat-
ion shaft drops down off the slope, lowering
the tonearm and starting playback again.
The tonearm drive motor continues to move
the cam until the position is reached where
SW2 is turned ON (tonearm still in DOWN
position).
i
(signal pin from lowering position sensor)
For manual playback operation, depress the
arm-elevation switch to raise the tonearm up
off the arm rest (UP), then move it to the
desired point over the record by hand. De-
pressing the arm-elevation switch again will
then lower (DOWN) the tonearm onto the re-
cord. Operationally, this follows the se
quence listed in items 2 through 7 above.
Also during manual play, when the tone-
arm is manually moved toward the center of
the record (off the arm rest), the platter
commences rotation. When the tonearm is
moved off the arm rest, PD6003 26 pin
goes to a high level, and the 8 pin goes to a
low level, starting the motor rotation.
414

PL-707
= Auto-return
1. When record playback is over, the tonearm
stylus goes from the band of audio grooves
into the lead out groove, and the pulse width
of the signal output from end sensor A and B
become more narrow. This informs PD6003
that record playback has ended.
The phase of the pulse from end sensor
A and B is set so that B leads A by 90°,
however this phase offset is not used for
detection of the end of playback, but to
prevent any unintentional operations from
sources such as record disc eccentricity.
2. When playback completion is detected, PD6003
pin 17 goes to a high level and pin 18 goes
low, starting the tonearm drive motor rotating.
As rotation moves the cam, the slope causes
the arm-elevation to go UP, raising the tonearm.
3. As the cam continues rotating, it strikes the
PU plate. This stops cam movement, but the
trip wheel continues rotating and turns the PU
plate. This results in the tonearm being return-
ed to a position above the arm rest.
4. At this position, light strikes the lowering
position detector and end sensor A and B (all
three at once), and pin 24, 25, and 26 of
PD6003 go to a low level.
5. One to two seconds later, PD6003 pin 17 goes
low and pin 18 goes high, and after the tone-
arm drive motor stops, it reverses rotation and
sends the arm-elevation back down the cam
slope. This lowers the tonearm on the arm rest
ending playback. 5
6. At the same time, the cam tums switch SW1
ON (switch SW2 is already ON). When both
switches come ON, both pin 17 and 18
(PD6003) go to a high level, stopping the
tonearm drive motor. Also, when the tonearm
reaches the arm rest position, pin 8 goes high,
lowering the tonearm and causing pin 5 to go
high. This causes the platter to stop rotating
and extinguishes the elevation-up display
LED, D28.
12
Auto-stop
When it is desired to stop record playback in
the middle of the record, depress the START/
STOP button. As the START/STOP button
is depressed, PD6003 pin 15 goes to a low level.
Pin 17 goes high and pin 18 goes low, starting
rotation of the tonearm drive motor. Rotation
causes the arm-elevation to ride up on the slope
of the turning cam raising the tonearm.
Also 6 pin goes to a low level, thereby illumi-
nating the START/STOP display LED, D30.
From here the operation is the same as that
for auto-return (above), items 3 through 6.
The START/STOP display LED, D30 are
extinguished by the tonearm drive motor
reversing rotation and tuming switch SW1 ON
and sending PD6003 pin 6 to a high level.
Auto-repeat
To repeat playback of the same record, depress
the repeat button. This causes PD6003 pin 12
to go to a low level. At the same time, pin 4
also goes low, illuminating the repeat display
LED, D27.
When the repeat button has been depressed,
after autoretum operations have returned and
lowered the tonearm on the arm rest, the
unit again goes into autolead in operations and
continues playback. (The platter motor con-
tinues to rotate.)
5. CIRCUIT DESCRIPTIONS
5.1 SIMPLE SIGNAL PATH
The PL-707 motor drive circuit consists of the
control IC PA2007, reference phase generator
IC PD1003, motor drive IC PA2008, and IC
TD62504P functioning to produce the various
operational switch signals.
The signal picked up from the speed sensor
section is amplified by the FG amp, then convert-
ed to the speed sensor signal voltage (DC) by the
F/V converter.
Reference phase voltage is obtained by extract-
ing the reference phase from PD1003 pin 15, pass-
ing it through the 1/2 divider, then sending it
through the P/V converter to be used as reference
phase voltage (DC).
The speed sensor signal voltage and reference
phase voltage are each passed through a buffer
amp and resistance and combined (compared).
The resulting voltage is taken from the IC PA2008
pin 6 and input into the absolute value amp, and
is used to contro] the 4-phase drive circuit motor
rotation voltage, maintaining the motor at a fixed
speed.
5.2 SPEED SENSOR SECTION
1. The speed sensor board consists of a single
printed circuit.
2. Above this, rotates a rotor with 400 magnet-
ized poles on its lower face. Output varies
in accordance with the rotational speed of the
rotor.
3. The output (frequency) from the speed sensor
board is 111Hz for 33 1/3 rpm and 150Hz for
45 rpm.
4, The output signal is sent to PA2007 as a
balanced input.
5.3 FG AMP
In order to square the waveform of the signal
obtained from the speed sensor section (output:
0.5 — 2.0 mV rms) prior to inputting it into the
F/V converter, it is amplified 69dB across a band
width of 20 to 160Hz.
5.4 F/V CONVERTER
1. Since the rotational speed is detected at a fixed
frequency, the frequency must be converted
to a voltage (DC). This function is performed
by the F/V converter.
2. Previously (in PA2004) this was done by a
2-frequency F/V converter, however, increasing
control gain of PA2007 allows a signa!-frequen-
cy F/V to be used.
PL-707
3. F/V converter gain does not change even with
rpm changes.
4. Switching reference frequency is shown in Fig.
5-1.
When the switch is OFF, speed is set to 33 1/3
rpm, and when the switch is ON, the variable
resistor used by 33 1/3 rpm is connected
parallel to the 45 rpm variable resistor. The
resulting total impedance establishes rotat-
ional speed. Thus, each time 33 1/3 rpm is
adjusted, 45 rpm must also be adjusted. This
arrangement prevents any rotational instabi-
lity that might result from both switches being
temporarily OF F when speed changes are made
by switching from 33 1/3 — 45 rpm.
5. Co, Ct, Rt, and Rfv are each connected to
ground, but the grounding point is very close
to that of PA2007. Also, Rt is a 0.01 uF
ceramic capacitor for noise and oscillation
removal, and it is grounded in close prox-
imity to PA2007 too.
Rt
45 r.p.m 33 1/3 r.p.m
ay
Fig. 5-1 Switching reference frequency
5.5 REFERENCE PHASE GENERATOR IC
PD1003
1. When power is tumed ON, the X’tal oscillator
block generates a 6.144 MHz signal by using
the externally connected crystal oscillator.
2. This is reduced to 6kHz by divider circuit 1
(1/1024), then this divided signal is input to
divider circuit 2.
3. The 6kHz signal input to divider circuit 2 is
further divided 1/27 for 33 1/3 rpm operation,
and 1/20 for 45 rpm, then transmitted from
pin 15 to PA2007 pin 8.
331/3 rpm: 222.2Hz
45 rpm: 300Hz
13

PL-707
5.6 1/2 DIVIDER AND P/V CONVERTER
The signal received at the 8 pin (item above) is Nom) Phase-locked area
further divided by 1/2 by the 1/2 divider, then
input to the P/V converter. The P/V converter
serves to convert the reference phase taken from
the 1/2 divider to DC voltage. Ne
The reference phase converted into DC voltage
is combined (by the buffer amp and resistor)
with the DC voltage from the F/V converter (and
used for rotation speed) and transmitted from pin
11 as a motor rotation speed control, signal to IC
PA2008 pin 6, then finally to the absolute value
amp (Fig. 5-2).
F-V
Rt
10k Vout
P-Vv
Fig. 5-2 (F—V) + (PV) circuit
F-v
output
—~ ret
Phase-locked area
discrimination
threshold
Vo
ier ——= f(z)
Fig. 5-4 F/V converter output
F-Vour
LOCK LED
Fig, 5-5 Phase-locked discrimination theoretical circuit
5.7 PHASE-LOCK DISCRIMINATOR CIRCUIT
When phase control is in effect, the output
characteristics of the F/V converter appear as in
Fig. 5-3. The portion that shows no change in 1.
speed when load torque is varied up and down can
be considered as the phase-locked area, and the
portion where large rotational speed changes occur
(as in Fig. 5-4) is outside the phase-locked area.
Thus, F/V converter output can be input into 2
an absolute value comparator having an upper and
lower threshold. A theoretical diagram of such
acircuit is shown in Fig. 5-5.
Noise
(Vout)
8.0
/
Vref = 5.0 Operating point
3.5
to (Hz)
Noise
Fig. 5-3 Input/output characteristics
5.8 STOP DISCRIMINATOR CIRCUIT
Depressing the START/STOP button of the
PL-707 transmits a stop signal generating a
reverse torque and applying a brake to the
motor. Motor rotation stops almost immedi-
ately.
The stop discriminator circuit functions to
detect low or high rotation speed through the
charge/discharge status of capacitors and
resistors connected to IC PA2007 pin 10
(To/STOP), and when rotation drops below
a certain speed, motor torque is dropped to
zero. A theoretical circuit diagram is shown
in Fig. 5-6.
After that, the platter turns a small amount
due to inertia, then stops.
R/S FF }
Normally
mon-conducting
»az008 —
TD62503P H
stary/
pa2007 Stop discriminator
circuit
Comparator
reference
voltage
f av
ND
PAZO08
Absolute vaiue amp
Fig. 5-6 Stop discriminator theoretical circuit
5.9 ABSOLUTE VALUE AMP AND ROTAT-
ION DIRECTION INDICATOR CIRCUIT
1. The signal at the 6 pin (control input) is com-
pared with the signal at the 5 pin (reference
voltage) and the difference in voltage is used
to generate current in the motor winding.
The input/output characteristics are shown
in Fig. 5-7.
2. The control input is higher than the reference
voltage (Vref 5V) when the rotation of the
platter is higher than specified speed. When
this occurs, the absolute value amp sends an
indication (instruction) to the rotation direct-
ion indicator circuit to generate reverse torque
in order to drop the speed of the motor.
3. The control input is lower than the reference
voltage (Vref 5V) when the rotation of the
platter is lower than specified speed. When
this occurs, the absolute value amp sends an
indication (instruction) to the rotation direct-
ion indicator circuit to generate forward torque
in order to increase the speed of the motor.
control current
Reverse torque region | Forward torque region
No-load operating
No-load operating point :
point
{ Vref -—Vin)
Fig. 5-7 Input/output characteristics
5.10 DRIVE CIRCUIT
1. The HA and HB Hall elements (6 magnetized
pole pieces fixed to the circumference of the
motor) are attached electrically 90° out of
Phase with each other. These elements are
used to sense the rotational position of the
motor.
2. The position sensing signal produced by the
Hall elements are each output to the block
diagram position signal synthesizing circuit,
and their waveforms are shaped as shown in
Fig. 5-8.
3. The staircase waves are each input into the
block diagram 4-phase drive circuit, and as
shown in Fig. 5-8, LA and LB alternate back
and forth in a 90° duty cycle (voltage) to turn
the motor.
4. LA and LB amplitude is in proportion to the
output of the absolute value amp.
90°| 90°{ 90
Ha
48
Fig. 5-8 Drive circuit waveforms
15

PL-707
5.
1.
18
11 REVERSE ROTATION SENSING CIRCUIT
The motor used in the PL-9 is the dual-direct-
ion drive circuit type, and if manually forced
in the reverse direction, it will continue to
apply a forward torque in an attempt to restore
forward rotation as long as it does not exceed
specified rotation speed.
However, when reverse rotation exceeds 45 or
33 1/3 rpm, the rotation direction indicator
circuit detects this as an overrun in the forward
direction and applies reverse torque in an
attempt to bring it to specified rotation speed.
Reverse torque applied to the platter already
rotating in reverse will further increase the
speed and the turntable will run out of control.
The reverse rotation guard circuit prevents the
platter from running out of control.
The equivalent circuit of the reverse rotation
sensing circuit consists of a D type flip-flop
(D input output at Q by CK triggering).
Dtype FF Absolute value amp
Both
directions
Singie
direction
Fig. 5-9 Reverse rotation sensor equivalent circuit
Motor
current control
Control current
Reverse
torque
Forward torque
Forward direction mode
Le aE rl
ele eit
Triggering edge
Pes eas
OH ter
Both directions operating
L
Fig. 5-10 Forward direction mode
Contro! current
Forward
rque
Reverse torq torque
Reverse direction mode
—_—-
ee ee pe
galerie
ax
One side directions operating
‘
Fig. 5-11 Reverse direction mode