Kenwood KT-990D User manual

QUARTZ
SYNTHESIZER
AM-FM
STEREO
TUNER
KT-990D
SERVICE
MANUAL
© 1988-1 PRINTED IN JAPAN
B51-3435-00 (G) 2658
Knob
(POWER)
Metallic
cabinet
Front
glass
(K29-2724-04)
(AO
1-1577-01)
(B
10-0896-03)
Panel
assy
Escutcheon
(TUNING)
(A20-5
340-02)
(BO7-1755-04)
Knob
(PROGRAM)
Knob
(Button)
Knob
(Button)
Knob
(TUNING)
(K27-179
1-04)
(K27-1761-04)
x
6
(K27-1761-04)
X
3.
(K21-0409-04)
Antenna
holder
AC
inlet
*
(J19-0875-03)
(E03-0
102-25)
°
Screw
terminal
board
(3P)
Phono
jack
(2P)
(E20-03
18-05)
(E13-0235-05)
Foot Slide switch *
(JO2-0190-15) x 4 (S31-2094-05) x 2
* Refer to parts list on page 42.
AGHE

KT-990D
CONTENTS
DISASSEMBLY FOR REPAIR ........ssssscssesssessesseseseerereeees 2 PE BOARD evinsscccetecscveonsnsceseuensadstedeaxesnavsracs deatucvsescsts suaseaiaess 27
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ADJUSTMENT PARTS LIST
REGLAGE.............. SPECIFICATIONS... cece sneseeseeeseresaeenseceensesrsseneeeas 53
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DISASSEMBLY FOR REPAIR
(Remove the metallic cabinet before proceeding to the
following.)
1. Loosen the screw on the tuning control knob, and take
out the knob. Then, remove the hex nut attached to the
tuning shaft (@).
2. Remove the 4 screws fixing the front panel to the
sub-panel from the bottom side (@), disengage the 4 lugs
on the top side, and take out the front panel in the
direction of the arrow.
3. Remove the 2 screws fixing the sub-panel to the chassis
(@).
4. Remove the 2 screws fixing the Sub-Circuit Unit (X13-
5750-11) (A/4) to the metal fixture (@), and take out
the Sub-Circuit Unit in the direction of the arrow.
5. When attaching the Sub-Circuit Unit (X13-) (A/4), take
care to insert the PC board between the lugs on the
sub-panel (@).
6. Place a cloth on the set main body, place the sub-panel
on the cloth as shown in the illustration, disengage the
lugs fixing the Sub-Circuit Units (X13-) (B/4) and (C/4)
to the sub-panel (@). and take out the PC boards in the
direction of the arrow.
7. Remove the 5 screws fixing the rear panel to the chassis
(@).
8. Remove the 8 screws fixing the Tuner Unit (X05-34 20-
11) to the chassis (@).
9. Take out the Tuner Unit (XO5-) in the direction of the
arrow (@). Be careful not to hit the metal fixture (No. 718
in the exploded view diagram) at this time.

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KT-990D
CIRCUIT DESCRIPTION
Function of components
Tuner unit (XO05-3420-1 1)
Use/Function Operation/Condition/Interchangeability
FM IF amplifier
Miner [Poe oes ee ed
FM OSC (TUNED) buffer
ee ne ee
ose
eee
OSC buffer
Q10 AM power switch Power switch for AM circuitry.
FM/AM power control When the base is ’H”’ (set by 5V from the microprocessor), Q10
is turned ON setting the AM mode.
Qi2=14 | PLL Woop Titer ae ric a RNG EC
Q15,16 DIS/DIR switching Goes ON when the input is “H”. Turns Q17 and Q18 ON.
Q17,18 DIS/DIR switching Driver. Q17 is ON for DIS and Q78 is ON for DIR.
Q19~21 WIDE/NARROW switching When the input to Q19 is “H”, Q20 is turned ON (Wide).
Q22 STOP control When the output from IC8 (2/2) is “L’’, Q22 is turned ON and
the STOP signal goes “L”.
Q23 STOP SENSE switching SENSE is High when the input is “H”.
Q24,25 REC CAL control REC CAL is set when the input to Q24 is “H”.
Components
Oo
aa Wi hy}
Q4,5
O
Q26 AM switching Switches the AM signal.
Q27 REC CAL switching Switches REC CAL.
Q28 Forced Mono control Forced Mono mode is set when the input is “’H
Q34 Auto quieting control Automatically controls the SUB demodulation level during the
small antenna input operation.
Q35 38kHz sine wave generator amplifier | Using the tuning circuit (88kHz) of LC as the load, turns the
rectangular wave into a sine wave.
Sends the 38kHz signal from the tank circuit to the SUB
demodulator at a low impedance.
Used as the load resistance to IC18
Performs current regulating operation together with Q37.
Used as the load resistance to IC 18.
Performs current regulating operation together with Q39.
Constant-current load (GND side).
Goes ON in Narrow mode to control the separation (Narrow).
Q36 38kHz buffer amplifier
Current mirror constant-current
circuit
Q43
Q44 SUB signal demodulation switching | OFF in Stereo mode, ON is Mono mode
Q51,52 OUTPUT muting Used for muting the output signal.
053,54 Muting control Muting is activated when the base of Q54 is “‘L”.
Gain switching
Q58.59 Regulator For +28V Tr.
}asos” Regulator For +5V PLL, prescaler IC
Regulator —17.5V for FL.
O55 Regulator Main 15V output.
Q56,57 Regulator —13V output

Tuner unit (X05-
Components
1C1 (LM7001)
1C4 (LA1245)
iC5 (M5218P)
1C6 (BA401)
IC7 (M5218P)
1/2
2/2
IC8 (M5218P)
1/2
2/2
IC9 (M5218P)
IC 14 (NJM4560D)
1C15 (LA3350S)
IC 16 (uPC78L12J)
IC17 (NJIM4560D)
1C18 (MC1495L)
IC19 (M5218P)
IC20 (NJM4560D)
1/2
2/2
IC21 (NJM4560D)
1/2
2/2
1C22 (M5231TL)
1C23 (uPC7805HF)
3420-11)
Use/Function
Generates REC CAL signal (400Hz)
120kHz noise tuning amplifier.
Operation/Condition/Interchangeability
Reference
frequencies
FM:
25kHz/50kHz,
AM:
9kHz/1
OkHz.
Noise amplifier
Noise
OUT
Noise
present/absent
output.
5V
output
when
present.
DIS/DIR.
OUT
5V
output
when
ANT
input
is
70
dB.
STOP
detect
OUT
Outputs
the
STOP
signal.
STOP detect
T meter control
Detects the TUNED bandwidth in FM mode.
Controls
the
lighting
of
the
T
meter
(red
portions
on
the
jeft
and
right).
Auto
quieting
control,
beacon
control.
Linear multiplier.
38kHz generator (sine wave)
3-terminal regulator
MAIN signal buffer
SUB signal demodul
ator
Subcarrier buffer
Stereo
demodulator,
deemphasis
Adds
the
MAIN
and
SUB
signals.
SUB
signal
demodulator
Current/voltage
converter.
Stereo
demodulator,
deemphasis
Adds
the
MAIN
and
SUB
signals.
SUB
signal
demodulator
Current/voltage
converter.
Vrer=1.8V, for +15V.
5V (output 5.6V).
Regulator
3
-terminal regulator
IF-DET UNIT (X86-1020-02)
Q1
Q3,4
Q5
Q6
Q7
1C2,3 (BA401)
1C4 (uPC1163HA)
IC5 (LA1231NS)
Operation/Condition/Interchangeability
Switches over between REC CAL, AM, etc.
Turns ON to rise the gain when in the NARROW mode.
Corrects distortion based on the auto stop signal input.
{F
amplifier,
band
muting
signal
generator,
S
meter,
quadrature
detector.
Use/Function
IF amplifier
PLL DET VCO
FM signal switching
Gain control
DCC ON-OFF switching
IF amplifier
IF amplifier
IF system
IC6 (NJIM4560D)
1/2
2/2
PLL DET DC amplifier
FM/AM signal amplifier

KT-990D
IF/DET unit (X86-1020-02)
IC8 (NJIM4200D) Tertiary distortion generator Linear multiplier.
IC9 (NJIM4200D) Secondary distortion generator Linear multiplier.
1C11 (M5218P)
1/2 | Tertiary current/voltage converter
2/2 | Distortion phase correction amplifier Tertiary distortion is Stereo mode.
“T€12 (M5218P)
1/2 | Secondary distortion current/voltage
converter
2/2 | Distortion output correction amplifier Increases distortion in NARROW mode.
1C13 (M5218P)
1/2 | Reference voltage generator VCC/2=7.5V.
2/2 | DET distortion correction amplifier Corrects the distortion in PLL DET.
1C14 (M5218P)
1/2 | Mono distortion correction amplifier Used for correcting the secondary distortion.
2/2 | Stereo distortion correction amplifier Used for correcting the tertiary distortion.
Sub-circuit unit (X13-5750-11)
IC1
(uPD4069UBC)
The
Schmitt
circuit
shapes
the
waveforms
of
the
CE,
UP
and
DOWN
pulses.
ica.auc7e7)
[Fide
SSSC~—~iSCSSSSCSCSCSCSCOCSCSCCCCC
IC5
(M52
18P)
Corrects
the
S
meter
tighting
point
error
due
to
temperature
RESET control When turned ON, activates RESET
M type frequency span switching When ON, the step is set to 50kHz with FM and 9kHz with AM
DOWN LED control When ON, the DOWN LED is illuminated.
UP LED control
S meter center grid control
When ON, the UP LED is illuminated
When ON, 5V is applied to the S meter center grid
When ON, 5V is applied to the T meter right side grid.
When ON, 5V is applied to the T meter left side grid.
When ON, controls 06.
When ON, 5V is applied to the emitters of 06, Q7, 8, Q16 andQ17,
and permanent ON control to grids Nos. 1, 2 and 6, and to permanent ON.
T meter right grid control
Q5
O6
Q7
fos SCSC*d meter gr convoh |
Q10 TS meter, ST, BIL, 1st/2nd/6th grid

Noise
detector
and
electric
field
strength
detec-
tor
circuits
1. Noise detector
This
circuits
detects
the
presence/absence
of
interfer-
ence
from
adjacent
stations,
etc.,
and
applies
the
microprocessor
with
the
Noise
present
(5V)
or
absent
(OV)
signal.
The
detection
output
is
extracted
from
AF
OUT
of
IC5
(LA1231N)
in
the
daughter
(2),
and
only
the
noise
component
is
amplified
by
120kHz
(center
fre-
quency)
tuning
amp
IC6
(BA401).
The
output
is
regulat-
ed
by
D50
and
D51,
and
the
comparator
in
IC7
outputs
“H"
=
14V
(L’:
—12V)
when
the
noise
DC
voltage
attains
about
1.4V.
This
output
is
5V/OV
converted
by
D52,R127
and
R128,
and
applied
to
the
microproces-
sor
port.
2. Field strength detector
The
S
meter
voltage
from
IC5
(LA1231N)
in
DT2
is
detected
and,
when
the
field
strength
exceeds
70
dB
with
respect
to
the
ANT
input
voltage,
the
IC7
output
goes
“H”
=
14V.
This
is
5V/OV
converter
and
supplied
to the microprocessor.
KT-990D
oT2 AF OUT
+3115V)
To Microprocessor
Sv: NARROW
Ov: WIDE
+BU15V)
S-METER
(X13)
1,63V
To
Microprocessor
Sv: DIRECT
OV: DISTANCE
—B (~13V)

Active Reception Circuit
START
Tuning operation start
No Manual mode
Preset tuning
Yes] Auto mode
RF SELECTOR RF SELECTOR
DISTANCE DISTANCE
IF BAND IF BAND
NARROW NARROW
Tunung start
Auto-scanning
Up/Down
_ Tuni ti t
Radio wave
detected?
Yes
Auto-scanning
stop
Field strength
measurement
Yes
RF SELECTOR
DIRECT
interference
detection
Interference
present?
iF BAND IF BAND
WIDE NARROW
Tunung operation End] If the ANT Input is very small (less than 1OdBF)
the Forced Narrow mode is activated regardless
of the presence or absence of interference.
RF SELECTOR
DISTANCE
Present

iC2:
CXP5016-2168(X13-5750-11)
Microprocessor
IC
Terminal
connection
diagram
&
keymatrix
connection
PY 1/PWM Voo 64
PY2/WP PYO 63
PY3/EC RST 62
N.C.
cE
ROTARY ENCODER “B~
RESET SIGNAL INPUT
1
2
3
4 PXO EXTAL 61 *
ne
(ar
YX
RFK
6
1)
5
PX1
XTAL
60
>
4.
194304MHz
<><>
<>
6
Px2
INT1
59
ROTARY
ENCODER
“A”
Cr
Xe
X72)
7
PX3
INT2
58
N.C,
i
8
PDO
VFDP
57
ve
DP
Ga
9
PDI
TO
56
~
pb2
PD3
PCO
PC!
PC2 '
PC3 N.C.
REYescaN
16
PFO
17
49
KEY SCAN Se
key
Sore
18
PF2
$14.47
19 PF3 $13 46
so 20 PEO $12 45
TEST 21 PEI sit 44 J
22 PE2 $10 43
AUTO
IF
BAND
SWITCHING
23
PE3
$9
42
BLK
PLL CE
PLL CLOCK
PLL DATA
24 PBO
25 PBI
26 PB2
27 PB3
REC CAL
IF BAND SWITCHING
MUTING
28
PAO
37
RF
SWITCHING
AUTO
RF
SWITCHING
29
PAI
36
AM
M—S
COMMUNICATION
REQUEST
A
30
PAZ
35
MONO
31 PAS
32 Vss
M—>S COMMUNICATION REQUEST B
Vss
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on NW DAU AA @ ©
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oa
Functions of diodes and switches
Band
Set
PLL
IC1(LM7001)
Band
B3 B2 B1 BO
Receiving
Frequency
|Inter-Channel|
Intermediate
Switches
Frequency
EM
|
87.5MHz~108.0MHz|
100kHz
|+10.7MHz|
—
50kHz
FMIN
L
H
a
Pen
a)
[
+10.7MHe
|
Prmin
|
tc
|
it
|
B30kHz~1610kHz
|
10kHz
|
+450kHz
10kHz
AMIN
*
—E {11 1 1
AM
|
531kHz~1602kHz
AMIN
|
x
O:
Without
diode
1:
With
diode
*:
AM
is
controlled
by
the
microprocessor
IC
(IC2)
in
the
(X13-)
unit.
AUTO
STOP
SENS.
SWITCHING
PLL Reference|/PLL Input PLL Output
Frequency
|
Terminal
}BO1
(P7)|BO2
(P8)|BO3
(P9)
L
=<
a

KT-990D
Port allocation
10
Backup (AC OFF) detection terminal. H: AC ON, L: AC OFF. When the
“L" level is detected, the backup status is set and clock is stopped.
(Note) The rise from “’L” to ’H” shall be faster than the rise of the reset
signal.
PY3 H ROTARY EN- Rotary encoder output signal input. H: ON, L: OFF.
CODER “B”
Serial shift clock output. H: Normal
so Serial display data output
so
|
N.C.
H ~
4
8~15 |PDO~ ' KEY RETURN O~7 | Key return inputs. H: Input present, L: Input absent. All terminals are
PDS pulled down (by 10K to 100K).
16~19 | PFO~ 0 KEY SCAN 1~ Key scanning signals.
PF3
H
| 20 [peo | 1 | H SD Auto-tuning stop display input. H: TUNE, L: SIGNAL.
21 PE1 | TEST Test mode setting input. H: Normal, L: Test.
Normally pulled up. When testing is required, the TEST terminal is
connected to GND.
Fe
L
H/L AUTO IF BAND IF band switch input signal for AUTO RF/IF switching mode.
H: Narrow, L: Wide.
Chip Enable output for PLL IC. Connected to pin 3 CL of LM7001.
[25 [per [0 |W PLL GLOGR | tock output for PLL IG. Connected wo pin 4 CL of LM7007.
[26 [pez [0 [4 PLL ATA | ate output for PLL IC, Comecied to pin DATA of LM7O0T.
28
=
i
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|
PA Muting control terminal. H: Muting ON, L: Muting OFF.
Conditions for Muting ON:
1) when Power is turned ON/OFF, 2) when the band is switched,
3) during recalling a preset CH, 4) during manual tuning,
5) during auto tuning, 6) during IF band switching,
7) during RF switching 8) during REC CAL ON/OFF
0
1
2
switching.
29 PA H/L AUTO RF RF switching signal input in AUTO RF/IF switching mode.
switching H: Direct, L: Distance.
PA H M-—>Scommunica- | Data transfer request signal output for M > S display.
tion request H: Communication request, L: Normal.
wo °
PA3
Vss
Ee
N}o
Freee, le Ne
fee IN ey eg
w
9)
—
w
1 Ww
wn Oo
H
MONO/ST FM Mono/Stereo reception control output
H: Mono, L: Streo
Vss
AM pack power control output. H: Power ON, L: Power OFF
RF SELECTOR RF switching signa! output. H: Distance, L: Direct.
Fixed at Distance (H) in other reception modes than FM.
w a n i)
ZL
H
H
°2)
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Wl! w N wn &
:
|

FM IF BAND
REC CAL
H
R/L AUTO STOP
SENS. LEVEL
IF band switching signa! output. H: Wide, L: Narrow.
Fixed at Wide in other reception modes than FM.
REC CAL reference signal transmission request signal output.
H: REC CAL reference signal transmission request, L: Normal.
Auto tuning stop sensitivity switching signal output.
H: High, L: Low.
Control signal output of pin 6 BLK of FL driver IC (LC7570).
H: FL display ON, L: FL display OFF.
N.C.
Only pin 56 shall be set ready for being pulled up.
a FL -B power supply connection.
ENG a
H ROTARY ENCOD- | Rotary encoder output signal input. H: ON, L: OFF.
ER “A”
7 Clock oscillation terminals. X‘tal: 4.194304 MHz.
-, CL2
Reset signal input. H: Normal, L: Reset.
N.C. On the PC board, shall be set ready for being pulled up.
Preset channel memory
@ When the MEMORY key is held depressed for more than
0.2 second then the key is released, preset channel
display “—"’ blinks for about 5 seconds. In this period,
select A/B and press a numeric key (1 to 0); the preset
channel memory is stored and the stored channel is
displayed.
@ When the MEMORY key is pressed again while “—"’ is
blinking, the display remains the same, but the unit gets
ready for another preset channel memory for another 5
seconds. {f nothing is does after the key has been
pressed, the preset channel memory becomes impossi-
ble in about 5 seconds; the preset channel display
returns to the last channel display, and the MEMORY
indicator goes off.
@ When an operation which is accompanied by muting is
activated while ““—" is blinking, the preset channel
memory mode is canceled immediately. This occurs
when one of the RF, IF, AUTO TUNING SYSTEM, REC
CAL, FM and AM keys is pressed or when the rotary
encoder is rotated. However, if the blinking of ‘“—" was
started during the AUTO TUNING SYSTEM operation,
the preset channel memory mode is not canceled even
when the AUTO TUNING SYSTEM key is pressed.
@ The MEMORY key is not accepted while the muting
timer is activated.
@ The MEMORY indicator lights while the key is pressed.
When the key is held depressed for more than 0.2
second, the indicator continues to light even after the
key has been released and, at this time, ‘“—” on the
preset channel! display starts blinking.
+B terminal (5V).
Programming feature
@ Last Ch -> Last Ch band is ChO of A> ChO of a
B: ChO of B- ChO of ‘a
REC CAL
@ During REC CAL operation, keys other than the REC CAL
key are not accepted.
@ The REC CAL operation is canceled by turning power
OFF (when the microprocessor is reset).
@ The preset channel memory mode is canceled when the
REC CAL key is pressed.
@ When the REC CAL key is pressed during frequency
scanning in the Auto Tuning mode, the frequency
scanning pauses temporarily. The frequency scanning
resumes when the REC CAL mode is canceled by
pressing the REC CAL key again.
@ When the REC CAL key is pressed during the AUTO
TUNING SYSTEM operation, the AUTO TUNING SYS-
TEM operation will be carried out until the end.
11
i
|
|
|

KT-990D
12
Keys valid only with FM band:
AUTO TUNING SYSTEM, RF, IF
Display and muting OFF timing at power ON (Resetting)
QO 0O5sec 1 sec 3 sec
$$ 4 + +H
up pin2 PLL da- Dispiay MOTE
CH” H” ta and ON OFF
detected display
data
trans-
ferred
Countermeasure against overrun
@ Turn power ON with the FM, RF and REC CAL keys held
depressed simultaneously. The microprocessor will be
initialized and data including backup data is cleared.
Other
@ Band preset scanning is possible in Test mode; when the
key for the same band is pressed successively, the preset
memory channels for the band are received in sequence.
Initial setup condition
Band: FM
Frequency: 87.50MHz
Tuning mode: Auto
RF: Distance
IF: Wide
Channel mode: A
ST/MONO: Stereo
Preset channel: ay
a)
Bea
SENS LEVEL: ‘’H” (all types).
REC CAL: OFF
PROGRAM: OFF
AUTO TUNING SYSTEM: OFF
Preset channel memory: FM 87.50 MHz for all of CH1 to
CHO.
AM initial setup condition
Frequency: 530 (631 kHz E-TYPE) kHz
RF: Direct. However, all indicators including RF SEL are
OFF.
IF: Wide. However, all indicators including IF BAND are
OFF.
Channel mode: A
ST/MONO: Mono regardless of tuning mode
Preset channel: 4%
Meat
SENS LEVEL: “’H” (all types).
REC CAL, PROGRAM, AUTO TUNING SYSTEM: OFF

Output Port Logic in Different Modes
At initial resetting (when backup is
NG) (FM Mode)
AUTO
MANUAL
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Auto tuning system (ATS)
The
ATS
operation
mode
can
be
turned
ON/OFF
only
during
FM
band
reception.
When
the
RF
or
IF
key
is
pressed
during
FM
band
reception,
the
ATS
mode
is
canceled
immediately.
If
the
ATS
operation
has
been
activated,
it
is
also
aborted
at
this
time.
As
the
final
ATS
operation
mode
is
stored
in
memory,
the
ATS
operation
is
started
if
the
final
mode
was
the
ATS
mode
when
the
microprocessor
is
reset,
power
is
turned
ON,
or
when
any
of
the
FM
band
key,
numeric
keys
or
A/B
key
is
pressed
during
receiving
a
band
other
than
FM.
When
the
rotary
encoder
is
rotated
in
the
ATS
mode
or
when
the
ATS
key
is
pressed
during
tuning
(frequency
scanning)
operation,
RF
is
set
to
the
Distance
and
IF
to
Narrow.
However,
if
SD
(microprocessor
pin
20)
“H”
is
not
detected
as
the
result
of
frequency
scanning,
the
RF
and
IF
mode
will
not
change
even
after
the
end
of
frequency
scanning.
Even
when
the
reception
status
changes
after
the
ATS
operation
has
ended,
the
ATS
operation
will
not
resume.
LOSYHIG *7
JONVISIG :H
Fo Lap 5 Crea
nw
zs Zz ae
»O
m™>
Z2Zz
am
=z
nn
rot zs mm
= or i
a F
= Oo
c as
3 a
>" =
bd c
3 3.
a i]
cas ®
=
©
a
Test
Frequencies
that
are
stored
in
memory
cha
nnels
in
test
mode
@
Band
preset
scanning
is
possible
only
in
Test
mode.
Note) The Test mode
is entered by
turning power
FM rEM 87.5MHz| FM 87.5MHz,
ON with the
A-2
89.1MHz|
89.1
MHz
TEST
terminal
(GND). As the
106.0MHz| 106.0 MHz
band preset
scanning is ac-
tivated in Test
mode, these
frequencies
canbe received
in sequence
with out press-
ingthe memory
channel keys,
87.5MHz
87.5MHz
87.5MHz
87.5MHz
87.5MHz
AM 530 kHz
87.5 MHz
87.5 MHz
87.5 MHz
AM 531 kHz
P o
butby just
630
kHz
630
kHz
pressing
one
of
990
kHz|
990
kHz]
—theband
swiches (FM
1440 kHz 1440 kHz /AM).
1610 kHz 1602 kHz
FM 87.5MHz| FM 87.5MHz
B-7 87.5MHz 87.5 MHz
87.5MHz| 87.5 MHz
| 87.5MHz| 87.5 MHz
87.5MHz| 87.5 MHz
13

KT-990D
14
Auto tuning system operation flowchart
Numeric key,
A/B key or FM key
pressed ON?
Rotory
encoder
rotated?
ATS mode?
RF : DISTANCE
IF : NARROW
125ms(Normal) or
500ms{Band edge)
POWER ON
RESRT?
Yes
ATS mode 3sec
inversion
Yes
32msec
Check SD
{pin 20).
requency
scanning?
RF : DISTANCE
IF : NARROW
512msec
RF : DIRECT
IF : NARROW
Muting cancel
512msec
RF : DISTANCE
RF : DIRECT
512msec
? NARROW
IF
512msec

1C1: LM7001(X05-3420-1 1)
PLL frequency synthesizer
| iF
2 PI
hase Detector |
Block diagram
syc
Charge Pump
XIN
XOUT o
FMIN o
AMIN o
4$ 54
CE CL DATA
Terminal description
Pin no| Pin name VO [Function
4 XOUT oO
EE ene
IN
Ss es ee
Data input.
Clock for controller (400 kHz).
Band data output.
BO1 can be used as a time base output
(8 Hz)
Local oscillator signal input.
Power supply.
VDD2 for back-up.
Charge pump output.
Power supply.
Data
input
11>
10us
|
Data
input
12>
10us
|
titifti
CL
(PIN@)
DATA
(PIN@}
CE (PIN@)
INTERNAL DATA

T-990D
1018: MC1495L (X05-3420-11)
MPX SUB demodulator
MPX SUB Decoder (IC18: MC1495L)
The Direct Pure MPX enables stereo decoding without
causing beat interference, in theory, by linear-multiplying
two analog signals (stereo composite signal and 38 kHzsine
wave sub carrier signal).
This unit provides the linear multiplier with high S/N ratio,
which is designed with the new theory. so that the high
signal-to-noise rationof 94 dB for the MPX unit itself and
the resistance to overmodulation of 400% (dynamic range:
106 dB are realized while the conventinal characteristics
are maintained.
Internal equivalent circuit
O 2 Output
O 14 (KXY)
38kHz 8 Oo
X Input
Y Input
4 O 12 Composite
50
O11
60
O10
30
O13
v 7
1C22: M5231TL (X05-3420-11)
Constant voltage power supply
Block diagram
INPUT
CIRCUIT
OVERHEAT = Cy
PROTECTION
OVER-WAVE OUTPUT
LIMITER
CIRCUIT
.
REFERENCE
VOLTAGE
GENERATOR
PHASE
CONPENSATION
CIRCUIT
VOLTAGE ADJUSTMENT
16

1C3, 4: LC7570(X13-5750-11)
FL driver IC
Pin configuration
(Top View)
Equivalent block diagram

T-990D
18
Explanation of terminals
SO~S33, Va: Segment outputs, pull-down resistor com-
mon terminal.
So $1 $33 Vev
Vop
BLK : Display OFF input.
BL R= 0" (Vos).....eccscscessssscssesssseeeeesserss OFF
BLK="1" (Vo)... csesesecccssssesecsseserereessees ON
CL, DATA, WR : Data inputs
Voo, Vss : Power supply terminals
Data input
CL Pin @
DATA Pin @
WR Pin @®
Display
Input at DO
DO~D33 : Display data
DA~DE_ : Dummy bit (don’t care)
DF : S29~$33 switching
Dn="1" ; Sn="1" (=Voo)
Dn="0" » Sn="0" (=Vr)
De "+ D29~D33 > S29~S33
De ="1" : ADI > $33
AD2 > $32
AD3 > S31
AD4 > S30
AD5 > S29
a
a
I
°
SIN: AD converter input.
1st point lighting level: 0.1 Voo (typical)
2nd point lighting level: 0.2 Voo (typical)
3rd point lighting level: 0.3 Voo (typical)
4th point lighting level: 0.4 Voo (typical)
5th point lighting level: 0.5 Voo (typical)
tl>4 usec
t2>4 «sec
t3 >20 psec

FL1: FIP12AM15S (X13-5750-1 1)
Fluorescent indicator tube
Grid division
&
|Cosrancr)
&:
71)
Cosmence
=)
[A
MeMons.)
» .
-PROSISN
"=
eeeser
: :
FM
—
(“aro
]
|
ISN.
|
Canvas:
laa
Ll
ea
ee
Bg
:
:
)
Et
Gt
Ele
8
La
TV
[wide] | adh NARROW
(wor) | BAND | MAIN suB BILINGUAL REC CAL
6G 5G 4G 3G62G 1G
Anode Internal connection
XA
XA
XS
x2
LA
LA
a5~g5
a3~g3
Z4
x1
[STEREO
|
[Memory
]
PROGRAM
FM
wie
(aiblet--
A
Ef
‘
X3 {AO ]
X5 wide] esol] NARROW)
a4~g4/ a2~g2 Z2/ ZI ,
x4 DP. Z3
ide
XA XS X6
Pin No.
Electrode
Pin No.
Electrode
i
5G
Porm
P%
Paw
4G
Pory
Pin
No.
50
51
52
53
54
55
Electrode
Pu Pu
Pu
NC
Ps
Pin
No.
71
72
Electrode
Py
Pa
Notes F: Filament G: Grid P : Anode NC : No Connection

20
INPUT OUTPUT TUNER ALIGNMENT
ITEM SETTINGS SETTINGS SETTINGS POINTS ALIGN FOR FIG.
FM SECTION
Unless otherwise specified, the individual switches should be set as following:
SELECTOR:FM IF BAND: WIDE RF SELECTOR:DISTANCE TUNING MODE:AUTO REC CAL:OFF
Connect a DC
(A)
98. OMHz Connect a DC L
DISCRIMINATOR 0 dev voltmeter between 98. OMHz (X86-) 0.000Vt10a¥ (b)
100dBuCANT input) P5(AFC)and TP6CVREF).
Connect a DC
BAND EDGE voltmeter between TUNING MODE:
(9)
2 BAND EDGE voltmeter between
(2) TP38(VT) and TP4(GND).
9
(A) Connect
Li2
98. OMHz (X86-) 0.000V+20aV
3
98. OMHz (X05-)
PROGRAM: OFF
TUNING MODE:
ANU 108. OMHZ
TP3CVT) and TP4(GND).| MANU 87. 5MHz
Repeat alignments 1 and 2 several times.
98. OMHz a DC voltmeter
PLL DETECTOR 0 dev between TP7(¥CC/2)
100dBuCANT input) and TP8(DET).
(A) Connect
MPX 98. OMHz a frequency counter
yco 0 dev between TP19(GND)
100dBuCANT input) and TP20(VCO).
(A)
1kHz,+75kHz dev
% Repeat the sequence from L1-L4—-+L7--L10—L1------ a few times.
(A)
7 IFT(L) 98. OMHz (BD 98. OMHz
1kHz,#75kHz dev
(A)
IFT(2) 98. OMHz (B) 98. OMHz
1kHz,+75kHz dev
(A)
98. OWH2
98. OMHz
(B) 98. OMHz
19, 000kH2+10Hz
Maximum amplitude
and symmetry
of the oscilloscope display.
Maximum amplitude i:
98. OMHz
=<
: od
and symmetry
of the oscilloscope display.
Maximum amplitude
and symmetry
of the oscilloscope display.
Position where the STEREO
indicator lights
when the control is
rotated gradually clockwise
from the most.
rant
=o
or naw
1
wv
D
xo co oe
1
Vv
AUTO-STOP
SENSITIVITY
SELECTOR: MAIN
ikH2,275kHz dev
12dBuCANT input)
«€)
98. OMHz
SELECTOR: MONO
1kHz,+75kHz dev *
80dBuCANT input)
(C)
98. OMHz
SELECTOR: MONO
ikHz,t75kHz dev *
80dBuCANT input)
()
DISTORTION (1)
DET
Minimum distortion.
DISTORTION(2)
MONO
(B) 98. OMHz Minimum distortion.
98. OMRz
DISTORTION(3) SELECTOR: MONO (B) 98. OMHz VRE Mininua distortion.
MONO 1kHz,t75kHz dev * (X86-)
80dBuCANT input)
Adjust 10, 11 and 12 alternately a few times to minimize the MONO distortion.
* E& T types: 1kHz, t46kHz dev.
Cc)
98. OMHz
SELECTOR: SUB
1kHz,+68.25kHz dev
Pilot:16.75kHz dev
80dBuCANT input)
(Cc)
98. OMHz
SELECTOR: SUB
1kHz, +68. 25kHz dev
Pilot:26.75kHz dev
80dBuCANT input)
After the adjustment of 14, adjust 13 again to minimize the distortion at 1kHz.
DISTORTION(4)
STEREO
YR7
(B) 98. OMHz (X86-) Mininur distortion.
DISTORTION(5)
STEREO
(B) 98, OMHz (X05-) Miniaua distortion.
c oo os