Akai AT-S55/L User manual

FM/AM QUARTZ SYNTHESIZER TUNER
mov. AT=-$55/L
STEREO INTEGRATED AMPLIFIER
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AT-S55/L
AM-U55/J
FM/AM QUARTZ SYNTHESIZER TUNER
moveLAT-S55/L
STEREO INTEGRATED AMPLIFIER
mops. AM-U55/J
THIS MANUAL IS ALSO APPLICABLE TO BLACK PANEL MODELS
SECTION 1 MODEL AT-S55/L SERVICE MANUAL ..... 3
SECTION 2 MODEL AM-U55/J SERVICE MANUAL ..... 25
SECTION 3. PARTS EIST coi caw ac cee ee eee sce aiwed 49
SECTION 4 SCHEMATIC DIAGRAM ................. 61
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SECTION 1
SERVICE MANUAL
MODEL AT-S55/L
TABLE OF CONTENTS
SPECIFICATIONS .. 1... 2. cc cece ce cette eee eee ee eee eee teense eneees 4
DISMANTLING OF UNIT . 0... cc ee ee eee eee eee neces 5
CONTROLS oo oie so S505 Boe he be 6 ww 5a od Re Rpellg Me Sid le el Sig dyes Daye eae Sieces: oe OOP 6
PRINCIPAL PARTS LOCATION ....... cece cece eee cence ee eee ee ee eee eee eee 7
VOLTAGE CONVERSION .... 0... ccc ccc ete eee eee eee teen ener teeta eens 8
ADJUSTMENTS 2.0.0... ccc ccc cc cc ee cee eee cee eee ee eee eee eee ee eee eens 9
1. AM (AT-S55L: MW) SECTION ADJUSTMENTS 1... 0.0... ccc eee eee eee eee ees 12
2. LW SECTION ADJUSTMENTS . 2.0... ec ce ee eee eee ee eens 13
3. FM SECTION ADJUSTMENTS .. 0.1... . eee ee eee (aihaing Sg Rba a aie ialy ete 3k 14
. CLASSIFICATION OF VARIOUS P.C BOARDS ... 0... eee eee ee ee eens 16
1. P.C BOARD TITLES AND IDENTIFICATION NUMBERS ........... cece ee eee ee eens 16
2. MODEL AT-S55; COMPOSITION OF VARIOUS P.C BOARDS ......... ce ee ee eee ees 17
3. MODEL AT-S55L; COMPOSITION OF VARIOUS P.C BOARDS ........ 2. cece eee ee ees 21
For
basic
adjustments,
measuring
methods,
and
operating
principles,
refer
to
GENERAL
TECHNICAL
MANUAL.

|. SPECIFICATIONS
FM TUNER SECTION
TUNING FREQUENCY RANGE
87.4MHz to 108.1MHz
USABLE SENSITIVITY (300 ohms) 1.9uV
CAPTURE RATIO
1.3dB
SELECTIVITY (HF, 400kHz) 65dB
IMAGE REJECTION 80dB
AM SUPPRESSION
60dB
SUB CARRIER SUPPRESSION 60dB
S/N RATIO (MONO/STEREO) 75dB/65dB
T.H.D. (MONO/STEREO)
STEREO SEPARATION (1kHz)
MUTING LEVEL
AM TUNER SECTION (AT-S55L:MW)
0.1%/0.15%
50dB
TUNING FREQUENCY RANGE
USABLE SENSITIVITY (BAR)
22dB
530kHz to 1,610kHz for U.S.A. and Canada
522kHz to 1,611kHz for other countries
100uV/m
(EXT.) 10uV
SELECTIVITY (IHF) 30dB
IMAGE REJECTION 48dB
IF REJECTION 75dB
S/N RATIO 55dB
T.H.D.
0.3%
LW TUNER SECTION (AT-S55L ONLY)
TUNING FREQUENCY RANGE 137kHz to 362kHz
USABLE SENSITIVITY (BAR) 200uV/m
EXT.) 20uV
SELECTIVITY (IHF 30dB
IMAGE REJECTION 48dB
IF REJECTION 75dB
S/N RATIO 55dB
T.H.D. 0.3%
OUTPUT SECTION
OUTPUT LEVEL FM (100% MOD.) 775mV
AM (30% MOD.) 250mV >
POWER CONSUMPTION |_20 Watts
POWER REQUIREMENTS | 120V, 60Hz for Canada and U.S.A.
220V, 50Hz for Europe except UK
240V, 50Hz for UK and Australia
110V/220V/240V, 50/60Hz internally switchable for the other
countries
DIMENSIONS 440(W) x 105(H) x 327(D) mm
17.3 x 4.1 x 12.9 inches
WEIGHT 5.4 kg (11.2 Ibs)
* For improvement purposes, specifications and design are subject to change without notice.

i. DISMANTLING OF UNIT
AT-S55/L
In case of trouble, etc. necessitating dismantling,
please dismantle in the order shown in the photo-
graphs. Reassemble in reverse order.
SCREWS
SCREWS
SCREWS
FRONT PANEL SCREWS
UPPER COVER
SCREWS

it. CONTROLS
mbostwo. AT-S55
‘AG T20V
s6OHZ 20W
Fig. 1 Controls
POWER SWITCH 12. BAND SWITCHES AND INDICATORS
1.
2. PRESET STATION KEYS AND INDICATORS 13. AM ANTENNA (ANT) SELECTOR (AT-S55L ONLY)
3. DIGITAL LED DISPLAY 14. AMLOCATION SELECTOR
4. SIGNAL STRENGTH INDICATORS 15. FM LOCATION SELECTOR
5. FM TUNING INDICATOR 16. FM/AM ANTENNA TERMINALS
6. FMSTEREOINDICATOR _. 17. OUTPUT JACKS (LEFT AND RIGHT)
7. TUNING KEYS : 18. AMFERRITE BAR ANTENNA
8. FM MODE SELECTOR . 19. AC ADAPTER INPUT FOR STATION MEMORY
9. PRESET SWITCHES AND INDICATORS 20. BATTERY COMPARTMENT FOR STATION MEMORY
10. RANDOM TUNING SWITCH 21. ACCORD (CEE, UK, SAA: AC INLET)
11. TUNING MODE SWITCHES AND INDICATORS

IV. PRINCIPAL PARTS LOCATION = |=.“ °-
AT-S55/L
PRESET SWITCH PCB NCTION SWITCH P
A3011C5040 i oASO1IC5050 : re
POWER TRANSFORMER
Fig. 2 Back View of Front Panel
BATTERY BAR ANTENNA
COMPARTMENT AM901
AT-S55T
warp
Bp-15SS LY.
POWER SWITCH
Swi
POWER SUPPLY PCB
A3011B5030 © CSA, AAL A3011C5060
A30I1B5080 : CEE, UK ,SAA
A3011B5090: U/T
Fig. 3 Top View

V. VOLTAGE CONVERSION
REAR SIDE
POWER SUPPLY PCB
{ if
Woo
POWER TRANSFORMER
FRONT SIDE
110V AREA ° FI 400mA 250V
220V AREA : F2 200mA 250V
240V AREA | F3 200mA 250V
Fig. 4 Voltage Conversion (U/T Model Only)
Models for Canada, U.S.A., Europe, UK, and Australia
are not equipped with this facility.
Each machine is preset at the factory according to desti-
nation but some machines can be set to 110V, 220V or
240V as required.
If voltage change is necessary, this can be accomplished
as follows.
1) Disconnect AC Power Cord.
2) Loosen holding screws and remove upper cover.
3) Remove existing Line Voltage Fuse and insert
required Line Voltage Fuse in thé proper fuse
holder.

VI. ADJUSTMENTS
AT-S55/L
BAR ANTENNA CORE LOW RANGE SENS.
TC! to TC3
FM_HIGH RANGE SENS
Tcl TC2 TC3 FRONT END
OKB)
REE RUNNING
STEREO
SEPARATION
(E_7~NS
©) raeizzne
:
(®) VR5(22KB)
RY (LEFT)
:
T3(BLK)
PILOT SIGNAL
CANCEL
wate.
aps WY LED SENS.
7Z\\ VR7(22KB)
CD sit
T2-a :CENTER VOLTAGE = ;
T2~b: DISTORTION
T2-a T2-b
Fig. 5 Tuner P.C Board A3011A5010 and Bar Antenna (AT-S55)