National SG -990A User manual

nth
ORDER NO. SDT-161
AM/FM MULTIPLEX STEREO RADIO-PHONO
WITH STEREO CASSETTE TAPE RECORDER
MODEL SG -990A | | |
ee
<EXPORT DIVISION> ;
MATSUSHITA
ELECTRIC
TRADING
CO.,
LTD.
MATSUSHITA
ELECTRIC
INDUSTRIAL
CO.,
LTD.
P.O.
Box
288,
Central
Osaka,
Japan
RADIO
and
STEREO
DIVISION

|
.
So
[o>]
=
©
D
|
J
ene
!
|
&
E
JEL SG-990A
CONTENTS.
Page
SPECIFICATIONS: sit3-4 0446 veer ties adits Merete slata te sea ed te ee Oe es a 1
PARTS IDENTIFICATION .. 20... 0... eee eee ee eet ee ee nea 2
DISASSEMBLY INSTRUCTIONS
ho: Remove: Chiassis:<.c. 3.0. 20ee8 at Sine ahh de Sate Onna le a aaa eS t Basaran 3
To Remove Cassette Tape Deck... 1... ce ee ee ee ee eee 3
To Remove Record Changer .. 1.0... 00. cee ee ee ee eee eee ee ne eee 3
To. Remove Speaker iy ec ie cs andictececs bie adds ote ek Gas & Sela wk Whee Bees BA ees 4
‘Lo: Remove:Baftle Board. scan ie Ose aa ee eee ea ny hin Boe a eh fee 4
SCHEMATIC: DIAGRAM: oases ie acesahaid Gord. Ss teers, @ RAS sO Seeds Sow ae dee Ne woe awe Dales 5
ALIGNMENT INSTRUCTIONS
AM-IF-&:FM ALIGNMENT. oa:cct exc ee a oe Bde ee Mea ee Sd ea al Swe 6
ALIGNMENT: POINTS teas. od:e 6 Soest erga Sa Soe or 2 idikg eed ele eres & aaa ae 7
FM-RF ALIGNMENT & FM STEREO ALIGNMENT ..... ce cee ee ee wee 8B
FM STEREO ALIGNMENT ... 20... cece ee ee eee eee 9
PARTS IDENTIFICATION (PRINTED CIRCUIT BOARD) ....... 0... 0c eee eee eee 10-13
CIRCUIT BOARD WIRING VIEW... oc ee eee eee nee 14
ALIGNMENT INSTRUCTIONS (TAPE RECORDER) .............-005 Calacanis Succes 15
MECHANICAL ADJUSTMENT-TAPE RECORDER ..... 2... .. 0. cece eee eens 16
TAPE TRANSPORT OPERATIONS ............. eamatlads dew @ aahe earner a ee Rae ee 17
PARTS IDENTIFICATION-TAPE DECK... 20... . ee ee te ee eee 18
DIAL CORD STRINGING GUIDE... 2. ee eee ees 19
TAPE RECORDER CIRCUITS ewtucy cls otgeh etd wheat Ns Gn te ale deus 20-21
TROUBLE SHOOTING GUIDE
Defective Recording Circuit .................0.2. w pledgeued Seg thats a gp taatat Roe Sena 22
Defective-Playback: Circults. 4.0.0 2 eee Ba we ee NE le AA ee ale i Bon ee hE Rte ee eS eS 23
Defective Mechanisti: h..ivec. 24 Get ela Bg Ree ee a ie Galati Gea e ae g so oa aE 24
EXPLODED. VIEW OF ‘GASSETTE DECK -s.2 syslee a eee ed wa ad eg enk Hak te eae te Beaten 25
SERVICING THE RECORD CHANGER ....... 0.2.2.0. 22 cee ee ee 26-27
EXPLODED VIEW OF RECORD CHANGER ....... rere reer ae Ee ere 28
RECORD CHANGER REPLACEMENT PARTS LIST ......... Badass 3 teow ee pA 29-30
CASSETTE TAPE RECORDER REPLACEMENT PARTS LIST ..........-...--+-0-- 31-33
REPLACEMENT PARTS: LIST -sacce 4 Gade vk Watered ede oe eel Pb ab ae a 33-40

Frequency Range:
Intermediate Frequency:
Transistors:
Integrated Circuit:
Diodes:
Sensitivity:
Power Output:
Power Source:
Speakers:
Phono:
Record Changer:
Cartridge:
Stylus:
Phonomotor:
Tape Deck:
Recording System:
Erasure System:
Tape Speed:
Frequency Response:
Record/Playback Head:
Erase Head:
Cassette Motor:
Cabinet Dimensions:
Weight:
SPECIFICATIONS
FM 87.5~ 108 MHz
AM 525 ~ 1605 kHz
FM 10.7 MHz
AM 455 kHz
2SK19 FM RF Amplifier
2SC920 FM Mixer
28C829 FM Oscillator
2SC829 Composite
2SC829 19 kHz Amplifier
2SA101 38kHz Amplifier
2SC829. DC Amplifier
2SB178 Eye Switching
2SA564 Squelch & 1st AF Amplifier (two)
2SB346 2nd AF Amplifier (two)
2SB176 ‘Driver (two)
2SB473 Power Output (four)
28B 175 AC Bias Oscillator
2SB324 AC Bias Amplifier
2SB346 Equalizer Pre Amplifier (two)
2SB175 Equalizer Pre Amplifier (two)
AN-203
SC-15 AFC
OA90 AM D.AGC
OA90 AM Detector
0A90 FM Detector :
OA90 FM Detector (pair)
0A90 Doubler \ .
0A90 —_—Doubler (pair)
OA90 FM MPX \ (two pairs)
OA90 FM MPX
0A90 LEVEL METER Detector
181211 AOC
10DC-1 Rectifier
10DC-1R_ Rectifier
12B-2-BIP-M_ Rectifier
FM 3yV/50 mW for 30 dB Quieting
AM 100uV/m for 50 mW Output
QW — QW (P.M.P.O.)
AC 110V, 125V, 210V, 240V 50 ~ 60 Hz
Two 6-1/2” PM Dynamic (162)
FA-707A
EPS-34TTCD Magnistate, with Stylus
EPS-13TTSD Flip-over, Diamond
AC Motor (120V 60 Hz) 4 speed
AC Bias 53 kHz
AC Erase
4.75 cm/sec.
50 ~ 10000 Hz
WY-425Z
WY -235X
MHT-5PS
Tuner Cabinet
19” (W) x 7-11/16” (H) x 15-3/8” (D),
483 (W) x 391 (D) x 179 (H) mm
Speaker System
9-1/8" (W) x 13-9/16” (H) x 7-1/2” (D}
Tuner Cabinet 8.6 kg (18 Ib. 15 oz)
Speaker System
2 kg x 2 (4 Ib. 6-1/2 oz x 2)
rear ET
MODEL SG-990A

MODEL SG-990A
PARTS IDENTIFICATION
REPLACEMENT PARTS-
Main Cabinet, Complete (SY K-710)
Speaker System, Complete (SY K-706)
T Knob _.
(SBN-338)
Baffle Board
(SYB-18)
Record Changer
{FA-707A)
N Badge Ass’y
(SYE-94)
edt eae Dirt Protector Cap
Panel
Ass’y
one
Level
Mete'
ea
(SYP-32) . eve eter .
Knobs-Band Selector a B ¥ Vv tue,
Function Selector one, Balance, Volume)
(SBN-308) ISENeS10)
Fig. 1 TOP VIEW
Screw No. 3 .
Screw No. 2 Screw No. 4
Screw No. 1. Screw No. 5
_—— Rubber Foot
Rubber Foot (SHG-314)
zs Specification Plate
(SGN-420)
Rubber Foot Rubber Foot -
SHG-314 upper
(SGH-314)
Screw No. 6 —— Screw No. 10
Screw No. 7
Screw No. 8 Screw No. 9
Fig. 2 BOTTOM VIEW
ar Pulley (ROR-14) Tuning Shaft (SDT-1324)
ies
Gaarener
Power
Switch
(EST-1030DU)
(SJJ-14)
Pulley (RDR-8)
««_ Volume Control (EVB-Q1AA01A54)
Power Transformer
(SLT-5W2-D) .«_Balance Control (EVA-QOAA01G15)}
Tone Control (EVB-OQ0AA01D14)
Dia! Pointer Ass’y (SYE-2)
Function Selector Switch (ESR-E283L15BE)
Terminal Jack
(SJE-76)}
Head Phone Jack
(SJJ-32)
Band Selector Switch (ESR-E283L15BE)
AFC Switch (SSH-16)
Ferrite Antenna Coil
(SLF-2E12)
Dial
Drum
(SDD-3030)
“Tuning Capacitor (EVC-5XR27B18S}
Pilot Lamp (XAM-43T)
Lamp Holder {SLF-105)
Fig. 3 CHASSIS
259: =

MODEL SG-990A
DISASSEMBLY
INSTRUCTIONS
To Remove Chassis (Refer to Figs. 1, 2 and 4)
1. Remove six (6) knobs from panel.
2. Remove ten (10) bottom cover mount-
ing screws, Nos. 1-10 as shown in Fig. 2.
3. Unscrew jack nut from head phone jack.
_4,
Remove
six
(6)
chassis
red
mounting
screws, Nos. 1-6 as shown in Fig. 4.
5. Unplug receptacle housing from plug
housing, 2 pin plugs from changer jacks,
2 pin plug from 2 pin jack and 16 pin
circuit board connector from cassette
circuit board. ;
6. To reassemble, reverse above procedure.
To Remove Cassette Tape Deck
(Refer'to Figs. 2 and 5)
1, Remove ten (10) bottom cover mount-
ing screws, Nos, 1-10 as shown in Fig. 2.
2. Unplug 16 pin circuit board connector
from cassette circuit board.
3, Remove four (4) cassette tape deck red
mounting screws, Nos. 1-4 and _ level
meter mounting screw as shown in Fig. 5.
4. To reassemble, reverse above procedure.
To Remove Record Changer (Refer to Fig. 5)
1. Follow instruction 1 to 5 above.
(Chassis Removal)
2. Remove four (4) changer mounting cir-
clips and washers, as shown in Fig. 5.
3. To reassemble, reverse above procedure.
Plug Housing (SJJ-34)
Receptacle Housing
(SJJ-20)
Scr
eye
Speaker
Jack
(R)
ee
Speaker
Jack
{L)
PLT
:
Screw
No.
3
Screw No. 2
Chassis Assembly
Screw No. 5
Fig. 4
Changer Jacks
Circlip & Washer No. 4
Ee
Screw
No.
2
Circlip
&
Washer
No,
2
Screw No. 1
Circlip & Washer No. 3
Circlip & Washer No. 4
Screw No. 3
Dial Light (XK AM37T300)
Bos eae e
Screw No. 4 \
Fig. 5

MODEL SG-990A
Sarai a RRR RRR a ee a a
DISASSEMBLY INSTRUCTIONS
To Remove Speaker (Refer to Figs. 6 and 7)
1. Remove four (4) rear cover mounting
screws, Nos. 1-4, as shown in Fig. 6.
. Unsolder wires from speaker terminal.
3. Remove four (4) speaker mounting nuts,
Nos. 7-10, as shown in Fig. 7.
4. To reassemble, reverse above procedure.
N
To Remove Baffle Board
(Refer to Figs. 6 and 7)
1. Remove four (4) rear cover mounting
screws, Nos. 1-4, as shown in Fig. 6.
2. Remove four (4) speaker mounting nuts,
Nos. 7-10, as shown in Fig. 6.
3. Remove six (6) baffle board mounting
nuts, Nos. 1-6, as shown in Fig. 7.
4. To reassemble, reverse above procedure.
Screw
No.
1
Screw
No.
3
Screw No. 2
Indicator Plate (SGK-300)
Speaker Lead (SWJ-28)
Fig. 6
I" Speaker (EAS-16P24SF)
Nut
No.1
:
Nut
No.4
Nut
No.7
a
:
Nut
No.9
Nut
No.2
;
i.
—Nut
No.5
Nut No.8 ‘ : —Nut No.10
Nut No.3 ae — Nut No. 6
Fig. 7

has SCHEMATIC
VY
-sav |
en Cee eee
Ric BI
DIAGRAM MODEL SG-990A
TR: TR3 TR2 D: D2
2SK19 2SC829 280920 SG-15. 0A90
FM
PF
AMP.
_
FM
OSC.
FM
MIX
AFC
AM
AGC
C145 IpF
Raa ae
aS3mA
sel K2 Ru 20 Co IP
Rie 27
Cre JID
Rr7 27
C2a M0022
D)
yy i Rig. 220K
.
ca}
8
3
Z
S
ou.
Hie.
ee
:
eee
:
5
4
esate
COMPOSITE
280829
|
koe?
SED)
Te
|
AMP.
19kKHz
AMP,
rt
|
ie
———
Fl Ph
DOUBLER
——38kHz
AMP
De
Tas
CaaS,
2SC829__ TRs 2SB178
(> DC AMP. EYE SWITCHING Ss
S R173 2.2K
Rite 22K |
|
$ OS Dis
2SB175
-gisyc00n
181211
28B
324
rq] 100K
RU 22K
x
8
~
BS
C75 Q0022 TR 21,22 TR 23,24 TR 10
2SB346
2SB175
2SAb5E
PRE
AMP.
PRE
AMP.
SQUE!
1st AF
1761
2
3.4
10
6
5 7
1548
9
11.13
14
#15
12
155
156
16
44
50
51
55
17
160
16
6018
19
20
22
21
«+74
17
R
76169
75
77
173,
81
62 63 64 32 33 34
65
66
67
36
35
37
38
40
41
42
45
46 47
68697071
149
52
53
161
58
162 165
163164
168 166
7879
80
174
172
8:
145
2 3
18
4
10
12
5
6
13
8
14
15
9
16
17
135 134
19
20
75
52
2153
2255
24 25
142
120
26
27 28
3e
Cc
80
81 14085
83
61
62
63 64
40
3839
41
42
65
43 44
66
67 45 39
46
47
70
71
72
73
48133
74
75
50
51
77787972
73
58 82
1411438684
88
87
89
929
aT
T3
Te Ts
T7
ly
Li
Tw
Lo Le
Tu
L2
L3
T12
T1
T2
Lio
Lt)
=6T13”
Le
Ss
$3-7
SB7
Ss
S3-1
S3-4
§3-2
SBa
S3-5
SB3
SB
S3-6
SF4
SB1
SE
MC-6
‘
:
MC-3,4 MC-1 fh
Notes:
1.
SB1
—SB7_
:
Band
Selector
Switch
in
“FM
STEREO”
position.
6.
S4
:
Phono
Motor
ON-OFF
Switch
in
‘“(
1...FM
2...FMSTEREO
3...AM
7.
Ss
:
AFC
Switch
in
“OFF”
position.
2.
SFi1—SF6
:
Function
Selector
Switch
in
“RADIO”
position.
8.
DC
Voltages
measured
with
vacuum
tube
voltn
~
(TR1i9
&
20...
TAPE)
©
condition.
3.
Si
:
Power
Switch
in
“ON”
position.
DC
voltages
shown
polarity
with
respect
to
chassis
4.
S2
:
Cassette
Motor
ON-OFF
Switch
in
“OFF”
position.
|
No
Mark
..........
FM
position
5.
S3-1
—
$3-12
:
Cassette
PLAY-RECORD
Switch
in
“PLAY”
position.
ee
eee
FM
STEREO
position
(
Dette
ne
AM
position
9.
S6
:
Power
Source
Voltage
Selector
1...common 2...240V 3...21
—-5-

Ds Dis
OAS0~=©=—-—S“« OAD x2
AM DET FM DET AUTO CHANGER
TP,
aro M> :
Le
mete
aA
Airway
CASSETTE
MOTOR
t t '
'
t
'
'
t
'
I
t
1
R20 100 - 2&7P 4,
¢. 000
ao)
G3 (00P
102
~8.6V)
legac
125 C126
V2200rr /6V 2200
GED Cia6 001
L RI33 3.9K
.
;
Le)
Wee
Rise
As
:
RI35
cs
+
6V/0
[237] im 1 n C109 Da
ORV 6 BV Ruz 330 Rig 220
\ Ree L5M ®
BX
R80 100K (49)
rs)
92.0.
TRIS Bmp
033-1
Rod
Ci OV Op 4.
"Ga Ringe RR
| 3 o|4 3fo 04
|
HEAD
PHONE
JACK
o|5
ajo
T1~Tio,
L6
| C7 O01 / ° No 2 f~73
.
S14
TR 23,24 TRato TRii12 TRi3,14 TR 15,16.17,18 hd : ape
28B175 2SA564 x 2 28B173 x2 28B 6 x2 2SB473 x4 ilo_ ole
PRE AMP. SQUELCH & 2nd AF AMP. DRIVER POWER OUTPUT
1st AF AMP.
0 16 6018 19 20 22 21 [phone] 26 27 28 29 133 134 113 119 135 121 123122152 151 138
76169 75 77 173,81 87 92 100 96102101 164 107109110115 114 124 125 = 129 i30
165 163164 168 166 7879 80 174 172 85 84 83 89 88 9091 95 93 97 98 99106 103 105 136 108 111 112 116118117126128127 137 131 132 140 139 141 143-145 149 150
|
25
142 120
26
27
28
36
29
30
37
136 108
109
123
:
124
131
127
129 128
130
125
126
132
1
«140
85
83
:
97
100
101
106
:
82 1411438684 8887 89 9291 93 94 95 96 98 99111 102103 110 104 105107 112 113 114 115 147 116 117 121
Te
Ts 77 Ts
Tio
To
Lia
Ti
«Lis
Li
Liz) Lis ;
S3-6
SF4
SB1i
SB2
SFi
»
SF2
S3-8
$3-10
S3-9
Sa
S14
SFs
SFe
S3-11
§3-12
S2
MC-3,4
|
MC-1
MC-2
MC-3
MC-10
MC-14
MC-12
MC-13
MC-11
MC-16
MC-8
Phono Motor ON-OFF Switch in “OFF” position. comme POSITIVE VOLTAGE LINE
AFC Switch in “OFF” position. weornaawmeeee - GROUND LINE
measured
with
vacuum
tube
voltmeter
under
‘‘no”’
signal
:
=—mzm_=n»
NEGATIVE
VOLTAGE
LINE
(AF
CIRCUIT)
soummonse NEGATIVE VOLTAGE LINE (IF, RF & FM MPX CIRCUIT)
wn polarity with respect to chassis ground.
Latent ee FM position
Sarah ae a ous FM STEREO position
eo cesexatenene te AM position
Power Source Voltage Selector
1...common . 2...240V 3...210V 4...125V 5...110V
NATIONAL RADIO PHONOGRAPH

MODEL SG-990A
MODEL SG-990A
ALIGNMENT INSTRUCTIONS (RADIO) ALIGNMENT INSTRUCTIONS (RADIO)
FREQUENCY & DISTANCE ON DIAL SCALE Table ALIGNMENT POINTS (RADIO)
To accurately align to the proper frequencies on the dial
scale, refer to Table at right and mark the edge of the dial
scale accordingly, using the ‘Start Point’’ mark on the dial
scale as reference point.
AM-IF & RF ALIGNMENT
Distance from ‘‘Start Point”
Frequency
550 kHz 13.9 mm
1500 kHz 125.5mm
90MHz | 37.2 mm
106 MHz | 116.1 mm
Output of signal generator should be no higher than necessary to obtain output reading.
Set band selector switch to AM.
Set function selector switch to RADIO.
Set volume control to maximum.
Set tone control to high.
Set balance control to center.
Maintain line voltage at 120 volts.
SIGNAL | SIGNAL
STEP GENERATOR |GENERATOR | DIAL
COUPLING FREQUENCY |
Fashion loop of several Gs: Point of
turns of wire and 455 kHz
radiate signal into | (400 “© Mod.) | (on/about
loop receiver.
com
| Fashion loop of several
radiate signal into
| (400 * Mod.)
loop of receiver. |
RADIO
SETTING
| honinterference. | across Te (2nd IFT)
| 600 kHz)
turns ot wire and 550 kHz 550 kHz | across ' Ls (ANT Coil)
mn petteinineen ee ceenaes eect eee mann ep ee ms
INDICATOR ADJUST REMARKS
| Ta (st IFT)
: Output meter -
| Adjust for maximum
Cee gcee nie eid: eat es
i Leia ale Rael aor Wee tee
Output meter |
| Adjust for maximum
output by sliding coil
(OSC, Coil) (Ls }along ferrite core.
| Speaker Jack (L)
i (Imp. 162)
Fashion loop of several
turns of wire and
radiate signal into
loop of receiver.
1500 kHz
(400 “» Mod.)
1550 kHz
Output meter | Adjust for maximum
across » (OSC Trimmer) output.
Speaker Jack (L) | CT4 ~ Repeat steps (2) and
(Imp. 162) | (ANT Trimmer) (3).
Notes: 1. Cement antenna bobbin with wax after completing alignment.
2. Make certain that speaker system is connected to the tuner when aligning.
FM-IF & DETECTOR ALIGNMENT WITH OSCILLOSCOPE
EQUIPMENT REQUIRED
Signal generator that provides 10.7 MHz marker.
Sweep generator that provides 10.7 MHz center frequency and 400 kHz sweep width.
OSCILLOSCOPE
Set sweep selector of oscilloscope to “‘External Sweep”’.
Set band selector switch to FM.
Set function selector switch to RADIO.
Set volume control to minimum.
Set tone control to high.
Set balance control to center.
Set AFC switch to OFF.
n line voltage at 120 volts.
Apply 60 °e sweep signal from sweep generator to horizontal input
terminals of oscilloscope.
Note: When step 1 aligning, unsolder lead between TP2-a & TP2-b
before alignment and resolder it after step 1 alignment.
SWEEP SIGNAL RADIO —
GENERATOR | GENERATOR DIAL
COUPLING ‘COUPLING SETTING
INDICATOR ADJUST | REMARKS
a =e Seepentateie ie, tt
High side thru. High side thru.
= tale to Rent Pietra noninterference.
Common to Common to loner )
chassis. chassis. 4
Point of
Connect vert. ee ae ee Adjust for maximum
amp. of scope i amplitude and proper
to point TP2 (FM 3rd IFT) linearity between
Common to (FM 4th IFT) +100 kHz markers
| (FM 5th IFT) 7 '
chassis.
__
(FM
Disc
IFT)
(Refer to Fig. 9)
High side thru. High side thru.
at PaidtOspOlnt ee noninterference
Common to Common to (on aaa )
chassis. chassis. a
Point of
Connect vert.
amp. of scope
to point TP3. To (FM Disc IFT)
Common to
chassis.
Adjust T9 so that
» 10.7 MHz marker is at
. the center.
(Refer to Fig. 10)
Note: 1. Remove line cord antenna from FM external when aligning.
2. Turn the core of T9 (FM Disc IFT) fully counterclockwise before alignment.
-—6
. Ls AM ANT Coil (550 kHz)
L1 FM ANT Coil
(90 MHz) . Te
CT1 FM ANT Trimmer
(106 MHz)
CTs AM OSC Trimmer.
(1,500 kHz)
L2 FM Collector Coil
(90 MHz)
T2 FM 2nd IFT
(10.7
MHz)
CT2
FM
Collector
Trimmer
(106 MHz)
T1 FM 1st IFT -.
(10.7 MHz)
La FM OSC Coil
(90 MHz)
CT3 EM OSC Trimmer _
(106 MHz)
CT4 AM ANT Trimmer
(1500 kHz)
Te AM 2nd IFT
(455 kHz)
L6 AM OSC Coil Ts FM 4th IFT
(550
kHz)
(10.7
MHz)
T4 AM 1st 1FT
(455
kHz)
(as5kHz)
T3 FM 3rd IFT
(10.7 MHz) T7 FM 5th [FT
(10.7 MHz)
Ts FM DISC. IFT
(10.7 MHz)
T9 FM DISC. IFT
(10.7 MHz)
TP3
TP2
TP4
T13
FM
MPX
Coil
T11
FM
MPX
Coil
(38
kHz)
(19
kHz)
T12
FM
MPX
Coil
(19
kHz)
Fig.
8
10.7
MHz
CHS
SS
ee
ee
5
10.7
MHz
SG
|
37.52
2250
(SG
imp
752)
|
752
|
To
Receiver
|
|
Fig.
9
Fig.
10
Fig.
11
FM
DUMMY
ANTENNA
op
ee

MODEL SG-990A MODEL SG-990A
|
ALIGNMENT INSTRUCTIONS (RADIO) | ALIGNMENT INSTRUCTIONS (RADIO)
FM-RF ALIGNMENT | SEPARATION ALIGNMENT
Set tone control to high.
Output
of
signal
generator
should
be
no
higher
Equipment
Required
than:necessary
to
obtain
a
puspucreeding:
Maintain
evo
leas
at
120
velte:
Stereo
Modulator
.......
Connect
Stereo
Modulator
output
to
EXT.
Mod.
terminal
of
signal
generator.
set
volume
contol
tomaxtinum:
eeu
palais
contielte
sage
Signal
Generator........
Modulation
Rate
of
19
kHz
Pilot
Signal.........
10%
Set
band
selector
switch
to FM.
Set
AFC
switch
to
“OFF”.
Modulation
Rate
of
Right
and Left
Signal...
... .
27%
60°
SIGNAL
SIGNAL
RADIO
Output
Level...
2...
0.0...
eee
eee
60
dB
GENERATOR
GENERATOR
DIAL
INDICATOR
ADJUST
REMARKS
Oscilloscope
COUPLING
FREQUENCY
|
SETTING
Dummy
Antenna
.......
Refer to
Fig. 11.
Fig. 12. R33 SEPARATION
VTVM
CONTROL
Connect to EXT. FM
Antenna terminal Output meter
through FM Dummy 90 MHz across
antenna. (400 < Mod.) Speaker Jack (L)
Common to chassis (Imp. 169)
(Refer to Fig. 11)
Connect to EXT. FM
Antenna terminal
through FM Dummy
antenna.
Common to chassis
(Refer to Fig. 11)
L4 (FM OSC Coil)
Li (FM ANT Coil)
L2, (FM Collector Coil)
Adjust for maxi-
mum output.
Control Setting & Procedure
TUNER 5 adit aaeaneest bBo Band selector switch to “FM STEREO”, Tone control to ‘‘CENTER”, Volume control to audible
level of speaker sound, AFC switch to “OFF”, Dial setting to approximately 89.5 MHz. Adjust
balance control so that output level from both units becomes equal.
EQUIPMENT COUPLING
ADJUSTMENT REMARKS
SIGNAL GENERATOR VTVM OSCILLOSCOPE
; Connect to EXT. Connect across CanAceio Adjust T12 & T10 for minimum
Note:
As
three
output
readings
will
be
present,
adjustments
must
be
made
at
center
frequency.
FM
antenna
speaker
jack.
Tarrninaleot
T13
(MPX
Coil)
indication
on
VTVM
from
the
left
terminal through (Left Side) VTVM T11 (MPX Coil) side output when the right side of
Output meter
across
Speaker Jack (L)
(Imp. 162)
CT3 (FM OSC Trimmer) | Adjust for maxi-
CT1 (FM ANT Trimmer) | mum output.
CT2 (FM Collector Repeat steps
Trimmer) | (1) and (2).
106 MHz
(400 - Mod.) ISM
Dummy antenna. (Imp. 16Q) stereo modulator is modulated.
Connect to EXT. Connect across Adjust R33 for minimum indication
P onnect to : :
FM antenna speaker jack. bcsinl of R33 (Separation on VTVM from the left side output
terminal through (Left Side) < Control) when the right side of stereo modula-
: VTVM. a
Dummy antenna. (Imp. 169) tor is modulated.
Note: When separation aligning, disconnect lead between TP4 and Oscilloscope (A) before alignment.
FM
STEREO
ALIGNMENT
19 kHz AMP. ALIGNMENT : : ar
|
Oscilloscope
(B)-(Left)
Oscillos
(B)-(Ri
:
[Gee
°
Equipment Required Mloscope (BI-(Right) o> orp
Stereo Modulator ........ Connect Stereo Modulator output to EXT. Mod. terminal of signal generator. ee (Eee) NIM Biche) ic oO
Signal Generator ....... Modulation Rate of 19 kHz Pilot Signal ..... 10%. a = ;
Output Level ........ 30 dB . oO
Frequency.......... Approximately 89.5 MHz pe Generator 5
Oscilloscope wm OO 0,©)
Dummy Antenna ....... Refer to Fig. 11.
Control Setting & Procedure
TUNEF es ee eee em Band selector switch to “FM STEREO”, Tone control to “HIGH”, Balance control to
“CENTER”, AFC Switch to “OFF”, Volume control to audible level of speaker sound,
Dial setting to approximately 89.5 MHz.
Notes:
1. When aligning, remove line cord antenna from External FM Antenna terminal.
2. When aligning, set separation control (R33) as shown in Fig, 12.
EQUIPMENT CONNECTION
SIGNAL GENERATOR OSCILLOSCOPE
Connect to EXT. FM antenna Connect vert. Amp. of scope T11 (19 kHz Coil) Adjust T11 ~ T13 for maxi- i
terminal
through
Dummy
to
point
TP4.
T12
(19
kHz
Coil)
mum
oscilloscope
pattern
\
antenna, (Refer to Fig. 11) POPU OU AO share: 713 (38 kHz Coil) of Sok. Fig. 13 RECOMMENDED EQUIPMENT CONNECTION FOR SEPARATION ALIGNMENT
ADJUST REMARKS ;

EO re creeper ete RS Se ee ar tn a OE ect pr ered et eg A eee ee ee Ren at Steg Se TTS TNT ET Tg TREY SIFT EET ETT
MODEL SG-990A
PARTS IDENTIFICATION
Fig. 14 IF (FM & AM) AND MULTIPLEX SECTION
=40—

MODEL SG-990A
PARTS IDENTIFICATION
8 Re
it 1a1.e ae
AT cin 06
e's
oOo
=
ee
HERE
| A A aE
= (6.
Fig. 16 RF SECTION (FM & AM)
= 44h:

MODEL SG-990A
PARTS IDENTIFICATION
ae
ye”
4,
rays
e
io
7
=h
&
a
Fig. 17 AUDIO SECTION
=49 =

MODEL SG-990A
f;
T14 AC Bias Oscillator
TP
a 8
0)
Ves £9
Pe po
\ fo)
3
a eS
£ & g
Ee & S YY" }o
wn @ :
oO
i neg) 8
a fo)
5
[S)
rom
£
ke
on
_
a
=
2
Fig. 18 CASSETTE TAPE SECTION
—~13—
0000000 0
O» Ore O:.-©
TP7 (R156)
TPe6(R155)

CIRCUIT BOARD WIRING VIEW MODEL SG-990A
TR9Q, 10
STEREO
8Vv
2.3V.
0
0
TRS
@ Grey =
Hown
@ sky blve 7 SF-b-/—~
@ back 72 tug
TR21, 22
1.9V
0.7V
0.6V
0.27mA
m) wia
a
mc)
MIC Tack (£)
Ored te fy ——
Brown 70 FP) mmm
@ Pelet BP —~
Level Meler
Oyellow 7 sF-s-|——
STEREO
@ Green 7 He -5\—
1(-F—
@ brown 7e
4.9V
0.4V
0.2V
0.8mA
TR19
ld) While
TR20
© tea 16 Pin Connect
@ Yellow
, ie Olrey To SF- 3-4
Oviolet
= @ Brown 70S -4-2£
@ To Ha-2
@ Red
@ Green
OQ wiite
@ Ky blue
@rellow
©) Sky blue To SF-5-3
@ Grey TosF-6-4
@ yellow 70 sF-S=38:
@QLbrown 7a SF -$-4.
@ Back
@alece 7? P*
Jlereo Eye
@ sky Blue
@wite 72 Pa—~
7e SE-S-4 ——
@ Wile
@ ked
‘ak Jo SE-S$-3 ——
Y) Sky Btve
@
@brown Te Py xs
@ waite
Sa
Pner Switch —— @ yellow Io Pr
Volyme Control
[[ STeReo_]
ie)
Cee Aoi
White
Oo mee
= ® Red
70 Head Phone Jack 2
7e
_
Noten
TR16, 18
Cy 0
B 11.8V
E 12V
Ic 18mMA '
SUP .~2980
tl
nu
ip
We
q
Sa O Grey ve sr-3-/
Je Ghassis Ground
@) Braided wire
Jo Chass’s Ground @ Braided Wite—
7o SB-/ -222 @ brown
@ Sky Btxe
@ VRs V&s
Br Zz 2
is 13 Zare 8
@ Grey 2 control |B
03 7
>
16 Pin. Connector J
—KAn Connector 2
QBrown Jo Pfs
TR4
—14—

| TR16, 18 TR13, 14
Terminal Jacks
S=eD) Grey To SF-b-2
@ Lown 70 Power Swilch
A}
8s
=8 &y
HN
ai x y
x * § a=
SS ES Bbtlame =O — eS
i x® Panto) Ld eee; Breen OMe
Hi @QGreen 7o PL2-/
1 black
SSS QBwn Jo 5F-4-1x,
Mess Oey 7e 5F-3-/ SSS
70 Connector I}
TO 70
70 Pra Connectop /2
To 1 Pin
Connector3
cK
nN
x3
VS
@®
\
58
:
VRs
Vix
8@
¢
Z NY
\ [ize a ys
: 2 Control > N
03° : iN
®®
16 Pa. Connector }-
An
lonnector
2
pee,
Switch
Qbrown fof; Osy blwé
Function Sekector Switch 70 Pin Tack 13
TR4 TR3 TR2
» GROUND LINE
—2.7V
[B.| -2.9v |
—3.6V
1.8mA
TRi11, 12
CO;W) DMO Bi wy) NM! —
POSITIVE VOLTAGE LINE
NEGATIVE VOLTAGE LINE (AF CIRCUIT)
NEGATIVE
VOLTAGE
LINE
(IF,
RF
&
FM
MPX
CIRCUIT)
NATIOQNAL RADIO PHONOGRAPH
—14—
PRINTED IN JAPAN

ALIGNMENT INSTRUCTIONS (TAPE RECORDER)
CONTROL SETTING & PROCEDURE
e Set function selector switch to TAPE.
e Depress ‘‘REC” buttons simultaneously.
e Set power source switch to ON.
e Maintain line voltage at 120 volts.
Refer to Figs. 18 & 19.
SL ERASE (Refer to VTVM-3 in Fig. 19)
VOLUME
STEP CIRCUITS VTVM CONNECTION CONTROL ADJUSTMENT REMARKS
Be de T14 Adjust 714 for Maximum in-
AC BIAS OSCILLATOR | Connect positive side to TPs (+) (AC Bias OSC) | dication of VTVM-1.
1 and negative side to TPS (--). MIN :
& ERASE (Refer to VTVM-1 in Fig. 19) Re4 Adjust Re4 for 13 V reading
9- (Voltage Control) | on VTVM-1.
AC BIAS OSCILLATOR | Connect positive side to TP6 and Li Adjust L11 for 5 mV reading
2 & ERASE Negative side to:lug. MIN | (AC Bias Trap Coil)| on VTVM-2
(Refer to VTVM-2 in Fig. 19) ‘ :
“ Adjust Lio for 5 mV reading
Onnect positive side to TP7 and on VTVM-3.
3 | ACBIAS OSCILLATOR negative side to lug. MIN Et Repeat steps (2) and (3).
AC BIAS OSCILLATOR Connect positive side to TP7 and
& ERASE (Refer to VTVM-1 in Fig. 19)
2. Do not touch R/P head Erase head when adjusting.
COV Range) (10m Range)
vrver-2
Seo rae
Notes: 1. Cement part of semi-fixed volume control (R64), as shown in Fig. 20.
4 negative side to lug. MIN T14
& ERASE (Refer to VTVM-3 in Fig. 19)
. Connect positive side to TPs (+)
5 | AC BIAS OSCILLATOR | and negative side to TPs (—-). MIN peg
(Voltage Control)
VrV/1-/ (20V Kange)
oF @
“Lo
Ras
Rush
TPT TP 6
Fig. 19 RECOMMENDED EQUIPMENT CONNECTIONS
RECORD/PLAYBACK HEAD AZIMUTH
ADJUSTMENT
Playback a Standard Alignment Tape and turn head
adjustment screw for maximum loudness.
—15—
(AC Bias Trap Coil)
When adjusting steps (1) and
(2), disconnect VTVM-1.
Adjust 114 for maximum in-
dications on VTVM-2 and 3.
Adjust T14 for 13V reading
on VTVM-1.
Repeat steps (2) and (3).
MODEL SG-990A
4
MODEL SG-990A
MECHANICAL ADJUSTMENT-TAPE RECORDER
PINCH ROLLER ADJUSTMENT (Refer to Fig. 22)
1. Switch set to PLAY.
2. Pull pinch roller in the direction of arrows with spring
gauge, as shown in Fig. 22.
3. Pull the pinch roller away from the capstan, start
motor, permit the pinch roller.to make contact with
the capstan and measure tension at time of contact.
4. The standard pressure of pinch roller should be 350 +_
50g. eo
5. If pressure is beyond limits, change the fixed position
of pinch roller spring and repeat the above measure-
ment or replace pinch roller assembly.
TAKE-UP TORQUE ADJUSTMENT
Take-up Torque Measurement with Torque Meter
(Refer to Fig. 23)
Equipment Required:
e Torque Meter (having a range of 20 ~ 100g/cm)
e Attachment (Take reel out of cassette tape, makes
2 holes through its frame, and attach it to the
torque meter with wire.)
1 Switch set to PLAY and put attachment with the
torque meter onto take-up reel.
2. The standard take-up tension of the take-up reel
should be 55 + 20 g/cm.
Take-up Torque Measurement with Tension Gauge
(Refer to Fig. 24)
Equipment Required:
e Tension Gauge
e Attachment
1. Switch set to PLAY.
2. Put attachment which is connected to tension gauge
by cord (about 30 cm) onto the take-up reel.
3. To read the number of the tension gauge, move the
gauge in direction of arrow without slacking the cord.
4. The standard take-up tension of the take-up reel
should be 55 + 20g/cm.
If the take-up tension is beyond these limits,
a) remove oil and dirt from flywheel belt (38) and/or
b) remove oil and dirt from the rubber part of the take-
up reel and/or
c) remove rust from pinch roller or replace with new
one and/or
d) replace clutch felt (54) or take-up arm (51).
—16—
Spring Gauge
Fig. 22
Torque Meter
eo Wite Attachment
sSomnLs
Takeup Reel
Fig. 23
Ss Attachment
Sr
| Cord
Tension )
7’ Gauge
Fig. 24

MODEL
SG-990A
|
MODEL
$G-990A
TAPE
TRANSPORT
OPERATIONS
-
PARTS
IDENTIFICATION-TAPE
DECK
PLAYBACK
(Refer
to
Fig.
25)
RECORD
(Refer
to
Fig.
26)
When
play
button
is
depressed,
play
button
lever
moves
When
record
and
play
button
are
depressed
at
the
same
eae
beri
Head
Panel
(9)
Reel
Ass’y
(Take-up)
(26)
brake
operating
lever
(43).
time,
play
button
lever
moves
brake
operating
lever.
The
brake
arm
(22)
which
stops
both
reels
is
then
At
this
time,
brake
operating
causes
one
leaf
of
the
pone
Head
released.
motor
ON-OFF
switch
to
make
contact
with
the
other,
REC
Button»
At
this
time,
brake
operating
lever
causes
one
leaf
of
the
starting
the
motor.
REC
button
lever
activates
the
;
:
;
i ; :
ae
REW
Button
—
REC
Safety
Lever
B
(25)
motor
ON-OFF
switch
to
make
contact
with
the
other,
playback-REC
Selector
Switch.
Operation
of
the
unit
is
starting
the
motor.
the
same
as
for
playback.
FF
Button
Pepiake
Ari
ta2)
Set
is
then
in
the
playback
mode.
Motor
drives
fly-
L.
—
Spring
P
(83)
wheel
(36)
by
a
belt
(38).
Note:
PLAY Button.
Reel
Ass’y
(Supply!
(28)
When
take-up
arm
(51)
moves,
take-up
idler
(55)
makes
If
the
knock
out
plug
of
the
tape
cassette
is
removed,
:
; :
err
Brel
—DC
Motor
(63)
contact
with
take-up
reel.
record
button
will
not
function.
In
order
to record
The
take-up
reel
(26)
begins
to
take-up
tape
by
means
of
cover
hole
with
adhesive
tape.
OPEN
Button
rotation
of
the
take:
Up
arm
(51).
;
This
set
uses
a
4-track
stereo
recording
system.
Push
Button
Ass’y
(2)
Head
Panel
Push
Spring
(21)
At
the
same
time,
pinch
roller
(11)
makes
contact
with
If
source
is
monaural,
the
same
signals
recorded
on
!
Pinch
Roller
Ass’y
(11)
Pop-up
Lever
Ass’y
(28)
the
capstan
in
order
to
start
the
tape
motion.
both
channels.
The
playback/record
and erase
heads
(21)
make
contact
“For
best
results
it is
recommended
to
use only
with
the
surface
of
the
tape.
Panasonic
C90
or
C60
cassette”.
3
_
Fig.
29
j
Motor
Mot
Motor
Eas
a
or
(63)
OW
ore
Motor
(63)
:
Switch
(59
{
Switch
(59)
i
| Belt
(38)
;
‘=
Belt
(38)
Brake
Operatin
sppneie
i
7
ait
6
Brake
Operating
ieee
fi
i
|
Take-up
Reel
(26)
|
Plate
(43)
—}
<=
ape
Tekeub
Reel:(26)
Plate
(43}-—(
ae
0
|
REC
Safety
Spoke
(62)
Brake
Arm
(22)
|
2)
on
Arm
(51)
Brake
Arm
(22)-—[) OC
1(@))sn0
ee
eee
REW
Arm Ass’y
(48)
Bracket
F
(82)
‘
|
eh
:
;
Chassis
Ass’y
(1)
,
7
a
heel
(36)
:
]
: é
Tape
/
Flywheel
(36)
me
A
Flyw
i
: :
:
—
—
Switch
Holding
Spring
(44)
Erase
Head
(14)
:
>It}
capstan
Erase
Head
(14)-—-4}
WAL
Capeten
ft
ae
CN
Oh
sarc
:
—~
REC
Safety
Lever
A
(60)
Record/Playback
Pinch
Roller
443
a
)4
Pinch
Roller
(11)
Head
(18)
==
Record/Playback
Head
(18)
He
=
FF
Operating
Plate
(40)
Sip
ee
-——}
1)
Switch
Holding
Springj°/U!
ey
Button
Hever
30
|
:
Plug
Button
Lever
a)
|
|
RF
eer
Assy
(44)
|
|
|
|
i
i
|
|
|
Belt,
Capstan
(38)
Spring
J
(32)
a
Pulley,
DC
Motor
(65)
Stopper,
Lever
(31)
Fig.
25
Fig.
26
|
Spring
|
(29)
; ‘
~Flywheel
Ass’y
(36
FAST
FORWARD
(Refer
to
Fig. 27)
REWIND
(Refer
to
Fig.
28)
Feds
anenlen
Cts
ywheel
Ass’y
(36)
When
FF
button
is
depressed,
FF
button
lever
moves
FF
When
REW
button
is
depressed,
REW
arm
(48)
is
moved
Operating
plate
(46).
forward
(in
the
direction
of
arrow)
by
spring
(49).
.
Then
FF
idler
arm
(44)
makes
contact
with
the
flywheel.
REW
idler
(48)
contacts
with
FF
idler
and
the
supply
Fig.
30
The
rotation
of
the
flywheel
is
transmitted
to
FF
idler reel
(26).
through
contact
with
the
flywheel
and
take-up
reel.
At
the
same
time,
FF
idler
contacts
with
flywheel
and
‘
REW
idler.
cae
The
rotation
of
the
flywheel
is
transmitted
to
REW
idler
AY
and
FE
idler
i
|
Demonstration
Tape
1
MIC
Stand
——Motor
(63)
(WN-123N)
—
3
Brake
Operating
-Belt (38)
fece
Motor
(63)
3]
Plate
43)
Take-up
Arm
Brake
{
Switch
(59)
7
Belt
(38)
Sac
Aa
eae
Ass'y
(51)
Operating
Plate
(43)
|
---e2
_
Take-up
Arm
up|
[a
j '
Brake
Arm (22)
—T
1 / |
Ass'y
(51)
FF Idler Ass’y (44)
REW Arm
Ass'y (48)
fees F.F Idler Arm (44)
REW Button Us! F.F Operating
Lever
Plate
(46)
‘ll | I HL F.F Button Lever
F.F
Idler
Ass'y
(44)__
|
Microphone
(WM-2201N)
Flywheel (36)
1 WD
Speaker Cut OFF Plug

eS
ETE
TT
ETE
EE
Tt
ce
pene
te
eres
annem
PTR
SN
a
RE
geen
MODEL
SG-990A
DIAL CORD STRINGING GUIDE
To Reassemble Tuning Gears
1. Put tuning gears together.
2. Connect the gears with the spring as shown in Fig. 32.
3. Set tuning capacitor to fully closed position.
Mount the tuning gear on the tuning capacitor with mounting screw and washer.
4. Rotate the two tuning gears in:the opposite direction. :
Pull gear spring about 7.5 mm, as shown. in F jg.. 32:
Mount
dial
drum
with
the
mounting
screw,
as
shown
in
Fig.
33.
Note:
/
After
dial
drum
is
fixed,
make
sure
that
if-there
is
no
back
lash
of
dial
drum.
s
Tuning Gear
i
(a)
NO
GOOD
(b)
NO
GOOD
Fig.
34
(3 Turns)
Notes:
To
Mount
Dial
Pointer
Assembly
1.
Tuning
capacitor
should
be
position-
1,
Set
tuning
capacitor
to
fully
closed
ed
at
maximum
capacity
(closed).
position.
‘
2.
Numbered
arrows
(1-17)
indicate
cor-
2.
Set
dial
pointer
to
starting
point
of
rect
order
of
stringing
dial
cord.
dial.
3.
Cement
dial
cord
ends.
3.
Attach
dial
cord
to
dial
pointer.
4. Screw two (2) drum cover mounting
screws hold to fix drum covers.
Fig. 35
—~19--

_ MODEL SG-990A
TAPE RECORDER CIRCUITS
woh
.
Recording Circuits (Refer to Figs. 36 & 37)
Signals
for
recording
are
selected
by
switches
SB
&
SF
and
applied
to
AF
Amplifiers
(SF
...MIC~Equalizer
Amp.).
The
recording
signals,
amplified
by
AF
Amplifiers,
passes
capacitors
(C70
~
73),
resistors
(Res
~
71)
and
Lio
&
Li1,
to
reach
recording
head,
and
is
finally
recorded
on
the
magnetic
tape.
R70
&
71
are
used
to
keep
the
head
current
constant
and
to
compensate
high
frequency
response.
;
As
Fig.
36
shows,
impedance
of
the
head
increases
in
proportion
to
the
frequency.
In
order
to
keep
the
head
current
constant,
output
impedance
R
should
either
be
greatly
increased
or,
if
it
is
low,
the
signal
voltage
applied
to
the
head
should
be
increased
in
proportion
to
the
frequency.
Res
&
69
are
used
for
this
purpose.
Lio,
11
&
C72,
73
are
resonated
to
record-
ing
(or
erasing)
bias
frequency.
Lio
&
11,
&
C72,
73
are
used
to
adjust
recording
bias
current.
where : Z=Impedance of Head -
V=Record Signal Voltage
i =Record Current
Frequency -———p»
Fig. 36
2. Recording Indicator Circuit (Refer to Fig. 37)
.
When
PLAY
and
REC
button
are
depressed,
a
portion
of
the
record
signals
is
applied
from
outputs
of
AF
Amplifiers
to
R143
and Ri4s.
Then
these
signals
are
rectified
and
reach
the
level
meter.
METER
as a fe
oes
or!
be Cas 001 :
cr dese
17 mn f WV
OOP © Rix 150K R135 82K | sae
a2 Cer 6V/0n
+
TRU |S |TRI8-0\ Tis
~& :
<8
SS
WA
§
i:
a
eT,
&
Birsék | Rw sek * Rog 10K
108
R7 0K
VW
C03 647
ES
Seon oy 22
ie
Kure 0K
AWW
,
:
1509?
R135
8K
Rg
82K
ys
[80K
hus
41x
Of7
Wes
yj
R70
22K
io
ERPS
l
aM.
Eee.
_
as
hyp
Ke9
16K
lis
Cu7
001
ae
(Saat
RI
22K
cn
Los
cD.
yee
;
C15
00022
Fig.
37