Pioneer TX-9500II User manual

- -l';)
-4€
n
{t.1i
\t ( A--a'
r-
.. *'!:4.-"'
fe;
f)-
(6.'ot^'o" -"*' "*" IIJSlll
(DrqoNEErl

Type Voltage Remarks
KC 120V
only CSA (Canada)
approved with de-emphasis
selectorswitch
(25psl75psl
KU 120V
only UL (U.S.A.) approved with de-emphasis
selectorswitch
l25trs/75psl
HG 22OY and 240V (Switchabte) SEMKO (Sweden),
NEMKO (Norway), DEMKO (Denmark)
and El (Finland)
approved
S110V,
120V,
22OV
and
240V
(Switchabte) Generalexport model with de-emphasis
selectorswitch
l25ysl50ps/75psl
TX-g'5ClCltr
MODEL
TX-gsOOII
COMES
tNFOUR
VERSIONS
DISTINGUISHED
AS
FOLLOWS:
. Service
informations
forTX-9500II/KU
isdescribed
onpage
5through
52inthismanual.
o Forservacing
of Kc, SandHGtypes
please
refer
to TX-9500II/KUmanual
with theexception
of
descriptions
inthe
"Additional
ServiceManual"
(p.53-p.86).
CONTENTS
1.
2.
3.
4.
5.
CONNECTION
DIAGRAM
SPECIFICATIONS
BLOCK
DIAGRAM
5
6
7
I
FRONT
PANEL
FACILITIES
CIRCUIT
DESCRIPTIONS
5.1 AMTuner
5.2 FM
Tuner
DISASSEMBLY
5.3 REC
LEVEL
CHECK
5.4 Power
Supply
CircuitSignal
Generator
Circuit
11
11
15
6.
7.
15
16
20
21
PARTS
LOCATION
7.1 Front
Panel
View
7.2 Front View with Panel
Removed 17
18
19
7.3 Top
View
7.4 RearPanel
View
8. DIAL
CORD
STRINGING

9. ADJUSTMENTS
9.1 FMSection 22
9.2 AMSection 26
10. EXPLODED
VIEWS
10.1 TopSide 27
1O.2 Bottom
Side. 29
10.3 Nomenclature
of Screws,
Washersand
Nut ... . . . 31
11. PACKING 32
12. SCHEMATIC
DIAGRAMS,
P.C.BOARD
PATTERNS
AND
PARTSLIST
12.1 Schematic
Diagramand
Miscellaneous
PartsList 33
12.2 FMFront
End
(AWB-023)
. 36
12.3 AMFM
lFAssembly
(AWE-070)
... 37
12.4 MPXAF Assembly
(AWD-009) 45
12.5 PowerSupply
Assembly
(AWR'128) 50
Additional
Service
Manual
1. CONTRAST
OF
MISCELLANEOUS
PARTS 54
*
2. KCTYPE
2.1 Schematic
Diagram
and
Miscellaneous
PartsList
2.2 PowerSupply
Assembly
(AWR-I29)
2.3 Packing
3. HGTYPE
3.1 Schematic
Diagramand
Miscellaneous
PartsList
3.2 MPXAF Assembly
(AWD-008)
3.3 Power
Supply
Assembly
(AWR'I30)
3.4 Packing
4. STYPE
4.1 Schematic
Diagramand
Miscellaneous
PartsList
4.2 MPX
AF Assembly
(AWD-010)
4.3 Power Supply
Assembly
(AWR-I31)
.. ..
4.4 Switch Assembly
(AWX-113)
..
4.5 Packing
56
59
61
62
65
70
73
74
77
82
85
86

1.
SPEC|FtCATIONS
Semiconductors 5
15
FETS
lCs
Transistors ......12
Diodes ....19
FM Section
Circuitry . . . MOS FET 2-stageRF ampli-
fier,
5-gang
variable
capacitor,
lF Band
Selector,Wide-band
linear detector, doublebal-
anced
NFB type PLL MPX
built-in p ilot signal auto
cancel
ler.
UsableSensitivity
. . MONO: 8.8dBf
(1.59V)
50dB
Quieting
Sensitivity. . MONO: 13.2dBf
(2.5tN)
STEREO:36.1dBf
(35pV)
Signal-to-Noise
Ratio
at65dBf MONO: 82dB
STEREO:71dB
Distortion
at
65dBf MoNo: wlDE NARRow
100H2 0.05% O.OIY,
l kHz 0.05% O.jlY'
10kHz O.07o/o 0.1Yo
15kHz 0.12Y"
STEREO:
100H2 0.17o O.3Vo
l kHz 0.07o/o 0.25%
lOkHz 0.2Yo 0.5%o
15kHz O.57o
Capture
Ratio.. . 0.8d8 2.0d8
AlternateChannel
Selectivity. . . 35dB 85dB
StereoSeparation.. ..lkHz: 50dB 45dB
50Hz
to 15kHz: 35dB 30dB
Frequency
Response 20Hzto 10kHz+0.2dB
2oHz
to
r
stHzloo']aa
SpuriousResponseRatio
. . 11OdB
lmage
ResponseRatio. . . . 120d8
lF ResponseRatio . 105dB
AMSuppression
Ratio
. . . . 65dB
Muting
Threshold . . 19.2dBf(5
ttY),34.1d8f(28pv)
Subcarrier
Product
Ratio
. . 11dB
SCAReiection
Ratio
. . . . . 62dB
Antennalnput
. ... 30Oohmsbalanced
75ohmsunbalanced
TX-s|5clCltr
AM Section
Circuitry ...lstageRFamplifier3-gang
variablecapacitor
Sensitivity
lHF,ferriteantenna
.. . 300pV
lHF,
external
antenna. . 15pV
Selectivity . . 30dB
Signal-to-Noise
Ratio.. . . . 55dB
lmage
ResponseRatio
. . . . 70dB
lF ResoonseRatio.. .... 65dB
Antenna ... Built-in ferrite loopstick
antenna
Audio Section
Output
(
Level/lm
pedance)
FM
('100%
MOD.) FIXED: 650mV/4.2kO
VARIABLE:50mVto
1.3V/3.6ks2
AM (30%
MOD.) . FIXED: 2OOnYl4.2kQ
VARIABLE:
'l5mV
to
400mV/3.6kO
Miscellaneous
Power
Requirements 120V60Hz
only.
PowerConsumption
. . . . . 25W
Dimensions . a20(W)x150(H)x395(D)
mrr
16-9
|
16x5-7
18x1
5-9l1
6 in
Weight .... WithoutPackage:
9.5kg
(201b
15oz)
WithPackage:
11.0kg
(241b
4 oz)
Furnished
Parts
FMT-typeantenna ....1
Operatinglnstructions ......1
ConnectionCordwithPinPlugs .....I
Hex.Wrench
(used
forfasteningTuning
knob). . . . . . . 1
NOTE:
Specifications
and.the
designsubject
topossible
modifica-
tionwithout
notice.
/r
l

2.CONNECTION
DIAGRAM
FM DE.EMPHASIS
SWITCH
Normafly, set this s,witch to "75tts."
Be sure to set it to "25ps." only when
listening to an FM broadcast (pre-
emphasis:25psl with a Dolby* system.
TX-9500[
GROUND
OSCILLOSCOPE
*
The
word
"Dolby" isatrademarkof Dolbv LaboratoriesInc.
TTYPE
FMANTENNA FMOUTDOOR
(ifstations
are
nearby) ANTENNA
AM ANTENNA
(indoor or outdoorl
>t
DISCRETE
4CHANNEL
FM ADAPTOR
!
{t
I
-)
I
I *-J-=
rl I
i----
AM FERRITE
BAR
ANTENNA
CONVE]\
OUTLET
coupledv
power sr'\,
t- |
tl
t=J
:NlENr
iT (not
Iwith
witch)
"l
lr
_JTII
power
lf-
lls
tl
I lr5
L-
oosoo16;sO
b'ossoifdon
TAPEDECK STEREOAMPLIFIER

3. FRONTPANELFACILITIES
POWERSWITCH
Setto ONposition
to turnonpower.
Pilotlamp
will light.
MULTIPATH ON: Multipath sound becomesaudible
from speakers.When installing FM
antenna, select antenna location and
directionso as to minimizethis sound.
Normally
setswitchto this
position.
RECLEVEL CHECKON: Usethis position
for setting
recordinglevelsof tape deck. A 44OHz
signal
(level
correspondingto 50% FM
modulation) is produced at approxi-
mately1.7
second
intervals.
SIGNAL
METER
Employ when tuningAM
tuning point occurs
when
toward
therightisobtained.
and FM stations.
Optimum
maximum meter deflection
TUNING
Usewhen
deflection
tune carel
(optimum
MUTING
Controls
noise
whr
tuning
opr
2:
OFF:
PILOT
LAMP
IF BAND
SWITCH
FM lF (intermediate
forwide
ornarrow. frequency)
passband
canbe setto
WIDE: Normally
setswitchto this
position.
NARROW: lf adjacentstation
interference
isa pro-
blemat the WIDE setting,setswitchto
this
position.
MULTTPATH/RECLEVEL
CHECKSWTTCH MEMORY
MARKERS
Single
leveroperatesbothMULTIPATH
andRECLEVEL
CHECK
switches.Withthe FUNCTION
switchat FM,
set
asrequiredfor the application.Besureto returnit to the
OFFposition when
it isnotbeing
used.
tFBAND
INDICATOR
Convenient
for designating
most
oftentuned
in stations.
Slidemarkers
with fingertip
to desired
positions.
OUTPUT
LEVEL
CONTROL
Adjusts
levelatOUTPUT
(VARIABLE)
jacks.
Clockwise
rotationincreasesoutputlevel.
OFF:

;.Optimum
' deflection
TUNINGMETER
Usewhen
tuning
FM stations.Firsttunefor maximum
deflection
of theSIGNAL
meter
(tov,ard
the
right),
then
tune carefullysothat the meterindicates
centerof scale
(optimum
tuning
point).
oraorueen
srEFEo
ruNEr
il-9500]l
MUTING
SWITCH
Controls circuit for cancellingbothersomeinterstation
noisewhentuning FM stations to provide a comfortable
tuningoperation.
TX-s|5ClCltr
FM STEREO
INDICATOR
with the FUNCTTON
switch
set
to FM AUTO (or FM
NOISE
FILTER),
the indicaror
will light
during
stereo
signal
reception.
FUNCTION
SWITCH
Switch
for selecting
type
of reception.
AM: AM broadcast
reception.
FM AUTO: FM stereoreception.
lf broadcast
isFM
mono, the mono modeisautomatically
selected.
FM NOISE
FILTER: Ser to this position
if compara-
tively high frequency noise becomes
objectionable
during
FM
stereo
reception.
Note that someloss
of stereo
separation
occurs
atthis
position.
FM MONO: FM monophonic
reception.
Set to this
position
if reception
at FM AUTO posi-
tionis
noisy
or signals
weak.
TUNING
KNOB
Knob for selecting
stations.Refer
to theSIGNAL
meter
when tuning AM stations
and to both SIGNAL and
TUNING
meterswhen
tuningFM
stations.
)ICATOR
)'
-_l
I
___l
Clockwise
2:
1:
OFF:
Set to this position to receiveonly strong
stations.
lf desired
stationcannot
bereceivedatposition
2,setswitch to this
position.
Setto this position
in locationswheresignals
areextremelyweak.
a

4. BLOCK DIAGRAM
FI,{
FRONT
END
l'-- Rr -; -- RFam; - f1i*"
!. crq rctr*@l -5.@l
r4
I lr'€i
,F I lrefl
+
It--- --i--L-- --_ --/ t L--r
ISWITCHES.
S'a^t ' FUNCTI0N
1.
AM 7. Fl
Sz,r,b
: MUTING
1 OFF 7.
S:a'd ' f40DE
1.IIULTiPA
S4a,b
' lF BAND
NARROW
<-
(.
vJ
55
FX
I
L
15o
t
3000
L
CND
Loca
| 0SC
POW
ER
0N<--) OFF
DE-
ENPHA:
flixer
1 Buffen
F11IF AHPLIFIER
& DETECTOR
t- WIDE
n*ftr;--rtr;-\
L=Jr=LL4Ld
Frf r Yr r7
--t ---1 --1 --1
Ceramic
f
ilfen
NARROW
Cer^am
ic
filfer^
e
J1A
TUNING
meter'
FM
detecton
T
WIDE
rnd.
NARROW
lnd
J
FI1IFAMP
IC
MUTINGCONTR
CIRCUIT
SIGNAL mefer-
L
AI1 TUNER __J
Al1
Our

SWITCHES.
S'a^ t :
S2,r,
b i
S34-
d :
FU
NCTION
1.
AM 2 FI'1 AUTO
3, FI"]
I1PXNOISE
FILTER 4. FM
I4ONO
IlUTI
NG
1 OFF ?. 1 3.2
11O
DE
1.IIULTIPATH
ON 2.
OFF 3.
REC
LEVEICHECK
ON
S4a,b ' lF BAND
NARROW
E WIDE
(. ' POWER
0N
--+ 0FF
56 : DE-
ENPltnSf
S 25aS
*-t5l.5
Separ
at
ion adL
U:- --J
-IFIER-&
DETECTOR
FM
detecl-on
- *+-;"rt I
1--th-Xl I r'rct' :
T1PX
DEMODULATOR OUTPUT
LEVEL OUTPUT
,\i
AF MUTING CIRCUIT
lrVARIABTE
RJ
L-r
FIXED
Rr
r ULTIPATH
HORIZ
(DtT
OUT)
VERT
.J5
#c-->AC LINE
S,
q
t6 o Stn
5os
o
Q+va
3
L.PF.
3AF
MUT.
IC
-_Jl REC
LEVEL
OSC.
l--r--.l
rLs.- --i
I o q.^
I "JU
l*r
L------r'\ |
src I I
S'a
L
l__ __ L _)
POWER
SUPPLY

5.CIRCUIT
DESCRIPTIONS
5.1 AM TUNER
The major components of the AM tuner are the
3-gangedvariable capacitor, a newly developed IC
(HA1197), and an AM ceramic filter. A block
diagram
of the HAlL97 isshown in Fig. 1.
This IC consists of an RF amplifier first stage,
followed by a mixer stage which also includes a
self-oscillating local oscillator, the IF amplifier 3rd
and 4th stages,and a detector circuit final stage.
The AGC (Automatic Gain Control) receivesan
AGC voltage from the output of the detector cir-
cuit, and applies it to the RF amplifier and IF
amplifier stages.The advantage
of the HA1197 isa
large
reduction in the distortion at low frequencies.
Whereas
the distortion at 100H2 was 1.57oin the
previous HA1138, this figure has beenreduced to
0.4Vo
(LOOHz)
in the HA1197.
TX-s|E'clcltr
5.2 FMTUNER
FM Front-end
The FM front end is composedof a tuning circuit
employing a 5-gangvariable
capacitor,a 2-stageRF
amplifier a mixer employing dual gateMOS FETs,
and a local oscillator with buffer. An equiva-
lent of a cascode amplifier is produced by AC
grounding gate-2 of the dual gate MOS FET,
allowing stable RF amplification at high gain.
The output signal of the RF amplifier is applied to
gate-l of the mixer stage
MOS FET, while the local
oscillator output signal is applied to gate-2. This
technique minimizes input power from the local
oscillator,resultingin low mutual interferenceeven
if the receivedsignalinput level is high.
A variation of a Clapp circuit forms the local
oscillator. Inclusion of a buffer amplifier between
local oscillator and mixer reduceslocal oscillator
load, eliminating distortion of the oscillation wave-
form. Drawing effect of the local oscillator is also
eliminated.
AF out
Fig.
1 Blockdiagram
of HAl197
2nd RFamp
FM75O UNBAL.
t-
FM
3OOOBAL.
L
Ceramicfilter
ANT
ToSIGNAL Meter
AGC line
1stRF
amp.
Localoscillator
Fig.
2 Circuitof FMfront
end

FM lF Amplifier
In this FM IF amplifier, there aretwo selectableIF
frequency pass bands,viz. WIDE band and NAR-
ROWband,selected
by the IF BAND switch.
Thiscircuit isshownin Fig. 3.
The SAW (Surface Acoustic Wave) filter used in
the WIDE band circuit, is a filter which works on
entirely new principles. Signals are carried across
the piezoelectric element surface by mechanical
vibrations. The advantages of this SAW filter in
comparison with a 2-element ceramic filter, is that
the group delay time flatness characteristics cover
more than twice (500H2) the band width while
still maintaining the samedegreeof selectivity.
The tetra-polar phaselinear filter makesuseof the
SAW filter characteristics to further improve the
degree of selectivity. Consequently, the WIDE
band circuit has been designed with the aim of
evenfurther improving the distortion factor.
The NARROW band circuit employs 5 2-element
ceramic filters for very good selectivity. This cir-
cuit is outstanding in its ability to reject interfering
signals,and is particularly suitable for areaswhere
adjacent stations are crowded very close together
on the FM band. The distortion factor too, isvery
closeto the valueobtained in the WIDE band.
Switching betweenthe WIDE andNARROW bands
is accomplished by switching a +B voltage supply
ON and OFF. But since the IF amplifier in the
NARROW band circuit is the same IF amplifier
used to operate the meters and the muting func-
tion, the +B voltage supply for the final stage IC
and diode (Dt) would also
beturned ON and OFF.
Switching the +B voltage supply for Dt ON and
OFF will causeD1to act asa switch. Whenthe +B
voltageisappliedto the anodeof D1, Dr isput into
a conducting state,with the signal
passing
into the
next stage.
Following the IF amplifier in NARROW band, or
following the WIDE band circuit there is a 5-stage
wide-band IF amplifier which produces sufficient
limiter effect.
FM Detector
The detector circuit used in the TX-9500II is a
super wide band linear detector circuit, a product
resulting from the study of distributed constant
type detectors.
The circuit is shown in Fig. 4.
M5109PR included in this circuit is an IC incor-
porating 2 pairs of differential amplifiers. The
loads of each differential amplifier are connected
to a seriesresonancecircuit where the L16, C3t
resonance frequency is higher than the inter-
mediate frequency (10.7MH2), and the L,r, C.,
resonance frequency is lower. The IF outputs
from each of these differential amplifiers are
modulated to the AM components which are then
detectedby Dr - D6.
<--H/v\# ComPoSlre
I I signol
IT
t' I
L---- --J
el ir
rro
!l
rq
il
,t4
lF omp
stoge
M5I09PR
Fig.
4 Circuit of FMdetector
fz
FIVMUTlNG
C]RCUIT
-JH|--1-IF--r
B -+- .\ -\
\-d-q-d
I ?d T-{ f-{
+ 'r 1- -1-
'" ,z 'rz ,7
Phose fi tter
AMP.
WIDE
bqnd IF
bond
lF AMP
Fig.
3 Circuit
of FMlF amplifier
L______.t\_a&toy

Anti-birdy Filter
The function of this filter is to remove any com-
ponent signals belonging to adjacent stations
within 200kHz of the tuned station which are
still contained in the signal after detection. If it
were not for this filter, beating in resonance with
the 10th and 11th harmonics of the 19kHz pilot
signal generated in the MPX IC of the final stage
would occur, and appear
asnoisein the reproduced
signal.
FM Multiplex Decoder
This section includes another IC recently devel-
oped by Pioneer, the PA1001. See Fig. 5 for the
block diagram.
This IC, an improvement over a previous IC
(HA1196), incorporates a pilot auto-canceller
circuit. This circuit filters out the leak canier
(19kHz) contained in the demodulated signal
without any loss in the frequency characteristics
of the audio signal. This filtering action is a con-
siderableimprovement over the previouslow pass
filter method. Other features include a wider
input dynamic range, and the ability to perform
well even when a 3O0Vomodulated input signalis
applied to the IC. S/N ratio and distortion factor
have also been improved by the incorporation
of a NFB circuit in the decoder amplifier. Distor-
tion hasalso been improved in the case
of MONO
signalsby connecting together the output circuits
of the L and R channels,and thus cancellingthe
out-of-phase distortion components contained in
the L and R channelaudio signals.
Fig.
5 Blockdiagram
of
PA1001
AF Amplifierand
Muting
This circuit employs the Pioneer developed IC
(PA1002).
The block diagramisshownin Fig.6.
This AF amplifier is a direct coupled amplifier
used as a differential NFB amplifier providing
TX-s'E'clOtr
outstanding dynamic range, S/N ratio, and distor-
tion factor. De-emphasis
is provided by inserting
a time constant circuit in the NFB loop of the AF
amplifier. The elements in this time constant
circuit include a metal film resistor (lVotolerance)
and a polystyrene film capacitor (27otolerance)
which havemade it possible
to reduce
de-emphasis
deviation
to within +0.2d8 to -0.5dB in the 20Hz
to 15kHz range.
The switching circuit for the muting function is
activated when a DC voltage from the power
ON/OFF detector section or from terminal no.8,
is received.The signalcircuit is then connectedto
gtound, thus preventingthe output of any signals.
This power ON/OFF detector circuit detects the
instantaneous change when the POWER switch
is turned ON or OFF, sending a trigger signalto
the switching circuit, and thus activating the
muting function. As a result, the popping noise
usually generated when the POWER switch is
turned ON or OFF, plus the residual noise, is
eliminated.
Fig.
6 Blockdiagram
of PA1002
FMControlCircuit
The FM control circuit usedto control the meter
driveand FM muting circuits, isindependentof the
audio signal circuitry. This circuit, too, incorpo-
rates an IC (PA3001) recently developed by
Pioneer.
The block diagramisshown in Fig. 8.
The PA3001 is very similar to the previous IC
(HA1137) in function and operation. It differs in
that the FM muting levelcan becontrolled extemal
to the IC. The input signalis supplied by the IF
amplifier in NARROW band (See
Fig. 7).
The FM muting function in the TX-9500II works
in 5 different ways:
r-_l
+lour
R
TOSTEREOind
13

1. Muting of the noise contained in the received
signal.
2. Muting at aspecificantenna input level.
3. Muting when not tuned to any station.
4. Muting when the IF BAND switch is switched.
5. Muting when the FUNCTION switchis switched.
The disconnection of the signal circuitry during
all of the above mentioned muting actions, is
performed by means of a switch circuit incor-
poratedinsidethe PA1002 IC.
1. Muting of the noise contained in the received
signal
Detection of this noise component is performed
in the NOISE amplifier (Qtt, high pass filter, Q'e)
shown in Fig. 7. After detection, the audio signal
appearsat terminal no.6 of PA3001, with the noise
components above 100kHz contained within this
audio signal being detected and amplified by the
NOISE amplifier. The output of this NOISE am-
plifier (noise component) is rectified at D13 and
D1a,
andthen removedas
a DC voltage.
This DC voltage is passed via Sr-b (MUTING
switch) and Sr (MODE switch), finally being ap-
plied to terminal no.8 of PA1002. Whenthe audio
signalcontainsahigh levelof high frequency noise,
the PA1002 switch circuit is activated, resulting
in the signalcircuit beingshortedto ground.
2. Muting at a specifrc antenna input level
The DC voltage at terminal no.L2 of PA3001 is
setto read at least 1.3V when the antenna
input is
less
than 14dB (5pV) with the MUTING switch in
position 1, and less
than 29dB (28pY) in position
F?
h po.ss
f iLter
TUNING
meter
SIGNALmeter
MULTIPATH
two. The adjustments are made by the semi-
variable resistors VR+ and VRr respectively.The
output of terminal no.1-2 of PA3001.is connected
via 32-6and 53 to terminal no.8 of PA1002, so
that when an output voltage in excessof 1.3V
appeaniat terminal no.12 of PA3001, the switch
circuit in PA1002 is activated, thus bringing the
muting circuit into operation.
3. Muting when not tuned to any station
When the tuned frequencies separatedby about
x70kHz from the broadcasting frequency, a DC
voltage appearsat terminal no.L2 of PA3001. This
voltage activates the switch circuit incorporated
inside PA1001, thus bring the muting circuit into
operation.
4. Muting when the IF BAND switch is switched
The Qrqbase voltageisdesignedto drop to 0V dur-
ing the instant the IF BAND switch(Sa
)ischanged.
(both contacts open during the switching action).
Consequently, Qtn is turned ON, resulting in +B
passing
via Q1e
to chargeCrr, as well as
passingvia
Dp to terminal no.8 of PA1002,
whoseswitch
cir-
cuit isthen activated.
5. Muting when the FUNCTION switch is switched
The Qrq basevoltage drops to 0V during the in-
stant when the FUNCTION switch (Sr) is tumed
from AM to FM, resulting in the momentar5r
opening of the +B switching section of the FUNC-
TION switch. This resultsin Q,, tuming ON, with
all consequent steps being the sameaswhen the IF
BAND switch waschanged.
Furthermore, Q2 has been addedto the circuit in
L OUT
R OUT
FM FUNCTION
+B
sr_b ?t'
v>
Sz
: MUTINGOFF-I- 2
Sr : MODE
IVULTIPATH-OFF-REC
LEVEL
CHECKON
Sa
: lF BAND
WIDE NARROW
+Br
+Be'
+d3
WIDEIF IF AMP.
t^
DETECTOR
MPX IC
( PA100t
)
AF MUT
IC
(PAl002)
I
Fig.
7 FM controlcircuit

order to prevent muting when the FUNCTION
switch is tumed to the AIVI position. In this case
+Bz is applied to the basesof both Q1e
and ez,
turning QreOFF, and Qz ON. Therefore, terminal
no.8 of PA1002 is connectedto ground, thus pre-
venting the muting circuit from operating.
The muting action is also inhibited when the
MODE switch (S3) is tumed to the REC LEVEL
CHECK position. In this case,
the MODE switch
shorts terminal no.8 directly to ground.
Fig.
8 Block
diagram
of PA3001
5.3 RECLEVEL
CHECKSIGNAL
GENERATOR
CIRCUIT
Thiscircuit, consisting
of onetransistorandanIC
@ c:t n+r
TX-s|5clcltr
(HA1452W), produces tone bursts every 8.4 sec.
for 1.7 sec. intervals by means of.a 440H2 signal.
The output level corresponds
to avalueequivalent
to an FM broadcast
with 5O7o
modulation. The cir-
cuit is outlined in Fig. 9.
The IC HA1452W incorporates two pairs of opera-
tional amplifiers, one being used as a 440H2 sine
wave oscillator circuit, and the other as square
waveoscillator, which cycleson and off every 3.4
sec.for 1.7 sec. The switching action of e, con-
verts this square wave into tone bursts. When the
square wave is applied to the base of e, , e, is
tumed ON and OFF, thus convertinginto a 440H2
tone bursts.
5.4 POWER
SUPPLY
CIRCUIT
Thiscircuit, too,employs
oneof Pioneer'srecently
developedICs (PA2002), resulting in better S/N
ratio, stability, and a greater degree
of reliability.
PA?OO2is an IC used to provided constant volt-
ages,
andincorporates
aprotection circuit. A block
diagram
is outlined in Fig. 10.
The protection circuit is composedof control cir-
cuits activated by overcurrents, and control circuits
activated by overvoltages.The protection circuit is
activated when either a current in excess
of 760mA
(resulting from an overload) flows through the IC
output (terminal no.10), or a voltagein excess
of
27V is applied to the IC input (terminal no.l).
Once this protection circuit is activated, no output
voltage will appearat terminal no.10.
Fig. 11 is an outline of the power supply circuit
used in TX-9500II. The Qr has been included in
this circuit in order to take up any excess
currents
above
the maximum current for the PA2002.
i
I
i
I
i
o,,
ilo
Fig.
10 Block
diagram
of PA2OO2
Qt
--=,, 12'u
AcLrNrgllp
l- YL
All L-rt--{---l 1 PAZoo2
roH-t3v
il!| |I
T
LL
@
To muting switch (Su
)
CreR+o
:R45
JF-r
cat k
n ---.l
-l
\l
440
Hz
Fis.
9Fig.
11 Power
supply
circuit
15

1.
2.
3.
6.DISASSEMBLY
Removethe 4 screws
(A) securing
both sidesof
the bonnet case.
Remove the 9 screws
(B) securing
the bottom
plate.
Remove all the knobs from the front panel. In
the case
of the TUNING knob, a securing
screw
must first be loosened. Now remove the 3
nuts (C) and the 2 screws
(D) securing
the top
of the front panel, which may now be taken
off.
Bonnet
case i"a**-'---
Front
panel
D
@-.:
TUNING
Knob
Loosen
theset
screw
16
Fis.12

TX-s'sclotr
z
F
z
-o;
-<
Y<
It
[J
A
I
a
::
l:i .
ia -
't\
z
=
FC'
-o
Pt
(,
z
F
E<
v<
.*\
l--:
i --;-
irgm-';
i rK!
:!
l. LryT,-
i
?
q)
C.a
--a
c@
9z
LI<
uJ
.J
l
F
),^
-o;
\Z<
i(--t,
i-*i
o
= !^
- z<
a Y<
@
L!r
CC --
= P=
OF- Y<
-O^
Y<
z
o
t-
<L
o=
o;
JJ IJJ
oe
F:
E=
o-tr
F.i

z
o
F
z
l
rJ-
>x
oo
E<
:E
E(,,
E=
=(9
ri{
:E
€t
.9X
o<
6
atr,
99
.=B
=<
F<
'i
z:
33X
'E
-9
I5-
isu
a !A
E ;ZR
Q 1<=
s, 6.o\i
> 6u-(/,
ao J=<
E
-
E6l
3h
J<
!l
PO
_t!
.s<
o<
b
ET
o :9
U.I FE
o it<
=
ut
E
J
lu
z
r
T
=
=
IIJ
F
2
o
E
lt
q
|r
uJ
U'
';t
g!z
i att
J<
1A

TX-s'E'C'CIU
=9 xe
o-5
>=
!
+ @
>ts
u-<
>
;o
ot
.9X
o<
E
E
=X
5=
=
uJ
F
r.
\
@
!
>6r
o9
i3
Io
l1t
-1
,l

9uJ
h|n F
i8 ?
x,l,
(JY l
l
ie
E.o
h!z
F<
:
f
F
tr
tt
g -+
; EP
= '= -1
f--
EF eX
ql ql
Ex
-l
z
z
Ll,l
z
s
_ (\l
E.i
h!z
F<
F
E
@
F
Tl:
;: a.{
euJ
(0
o
I
o
2
th
uJ
UJ
.P-
3
v)
=
u.l
5
J
uJ
z
o-
E
ul
t
a
t\

7.
3.
4.
5.
6.
8. DIAL CORD STRINGING
1. Remove the top cover and the front panel
(p.
16).
Rotate the front-end variable capacitor shaft
completely in the clockwisedirection.
Tie one end of the cord around the protruding
pin on the inside of the dial drum assembly.
Fix the dial drum assembly to the variable
capacitor shaft so that the setscrewis pointing
upwards.
Pass
the cord tied to the dial drum assembly
through the cut out section of the dial drum
assembly,andpass it overpulley A, B and C.
Then wind the cord 3 times around the dial
Spring
Protruding
pin
8.
T)(-9Eic'c,il
shaft assembly,
ffid pass
it overpulley D. From
pulley D, wind the cord twice around the dial
drum assembly along the grooves provided,
and then tie to the spring.
Rotate the dial tuning shaft to check for any
abnormal behavior in the movement of the
cord and dial drum assembly.Then cut off the
remaining
cord.
Rotate the dial tuning shaft completely in the
counterclockwise direction. Adjust the dial
indicator to the starting point on the left hand
side of the tuning dial scale,and then tighten
the cord.
Starting
point
I
indicator
V."'\
r' Front-end
Dial
shaft
Fig.
13
21