Sony LBT-A790 User manual

LBT-A790/A7995
SERVICE
MANUAL
AEP
Model
LBT-A790
E Model
LBT-A790/A795
Australian Model
LBT-A795
Tourist Model
LBT-A790
+ LBT-A790/A795 are composed of following models.
As for the service manual, it is issued for each component model,
then, please refer to it.
COMPONENT MODEL NAME FOR THESE SYSTEM
LBT-A790 LBT-A795
aeP| it | @ [cis] € | ea] sP | my JE E [mx [aus
POWER-AMPLIFIER TA-A790N
PRE-AMPLIFIER TA-A790E
CASSETTE DECK TC-A790
TUNER ST-A790
CD PLAYER CDP-M46 CDP-C433M
SPEAKER SYSTEM $S-D790AN
AUS : Australian IT: Italian
MX =: Mexican BA : Saudi Arabia
G : German MY : Malaysia
SP: Singapore JE : Tourist
STEREO COMPONENT SYSTEM
ONY.
English
94D0570-1
Sony Corporation Printed in Japan
Comsumer A&V Products Company © 1994.4
9-959-479-11 Home A&V Products Div. Published by Home A&V Products Div.
Quality Engineering Dept.

NOTE:
@ Items marked "*” are not stocked since
they are seldom required for routine service.
Some delay should be anticipated
when ordering these items.
Ref.No. Part No. Description Remark
@ Abbreviations
AUS: Australian
1-467-614-11 REMOTE COMMANDER (RM-S721)
1-501-374-11 ANTENNA, LOOP
1-501-594-11 ANTENNA (FM) (AEP, IT, CIS)
1-501-659-11 ANTENNA (FM) (EA, E, MY, SP, JE, MX, AUS)
1-551-734-11 CORD, CONNECTION (PIN-PIN)
(EA, E, MY, SP, JE, MX, AUS)
1-590-823-11 CORD (WITH CONNECTOR) (3P-11P-11P)
1-690-727-11 CORD (SPEAKER) (E, EA, MY, SP, JE, AUS, MX)
1-751-179-11 CORD (WITH CONNECTOR) (3P-15P-15P)
1-751-180-11 CORD (WITH CONNECTOR) (11P-11P)
1-765-462-11 CORD (WITH CONNECTOR) (3P-3P-3P-3P)
+ 3-350-154-01 CUSHION (TC)
3-758-344-11 MANUAL, INSTRUCTION (FOR CDP-C433M)
(ENGLISH, FRENCH, SPANISH, CHINESE)
(A795:E, AUS, MX)
3-758-394-41 MANUAL, INSTRUCTION
(ENGLISH, FRENCH, SPANISH, PORTUGUESE) (AEP)
3-758-394-51 MANUAL, INSTRUCTION
(GERMAN, DUTCH, SWEDISH, ITALIAN) (AEP, 6, 17)
3-758-394-61 MANUAL, INSTRUCTION
(ENGLISH, GERMAN, RUSSTAN, POLISH) (CIS)
3-758-394-71 MANUAL, INSTRUCTION
(CZECH, HUNGARIAN) (CIS)
3-758-394-81 MANUAL, INSTRUCTION (ENGLISH, FRENCH,
SPANISH, CHINESE) (EA, E, MY, SP, JE, AUS, MX)
* 4-927-355-01 CUSHION (ST:MADE IN FRENCH)
+ 4-929-563-01 CUSHION (CDP-M46) (ST:MADE IN JAPAN)
* 4-944-040-01 CUSHION (FRONT) (CDP-C433M) .
* 4-944-041-01 CUSHION (REAR) (CDP-C433M)
4-955-663-51 INDIVIDUAL CARTON (ST)
4-956-911-01 LID, SLIDE (FOR RM-S721)
. 4-965-030-01 INDIVIDUAL CARTON (TA-ST-TC) (A790: AEP, CIS)
* 4-965-031-01 INDIVIDUAL CARTON
(TA-ST-TC-CDP) (A790:E, EA, MY)
* 4-965-032-01 INDIVIDUAL CARTON (TA-ST-TC-CDP) (A790:SP)
* 4-965-033-01 INDIVIDUAL CARTON (TA-ST-TC-CDP) (A790: JE)
‘ 4-965-034-01 INDIVIDUAL CARTON (TA-TC) (A790: AEP, G, IT)
* 4-965-036-01 INDIVIDUAL CARTON (TA-ST-TC-CDP) (A795:E)
‘ 4-965-037-01 INDIVIDUAL CARTON (TA-ST-TC-CDP) (A795: AUS)
MX : Mexican
G : German MY : Malaysia
SP : Singpore JE : Tourist
Ref.No. Part. No. Description Remark
* 4-965-421-01 CUSHION (TA)
* 4-967-148-01 INDIVIDUAL CARTON (TA-ST-TC-CDP) (A795:¥X)
. 4-967-903-01 INDIVIDUAL CARTON (SS) (A790: JE)

SERVICE MANUAL
This set is the Preamplifier
section in LBT-A790/A795.
A-AT90E
AEP Model
E Model
Australian Model
Tourist Model
SPECIFICATIONS
an an Power consumption 1sW
Audio input —_| Jack type Sensitivity Impedance Mass ‘Approx. 3.9 kg (6 Ibs 10 02)
VIDEO 1/MD | Phono 435 mV 47 kohms Dunensions Baris perpen
VIDEO 2/DAT | Phono 435 mV 47 kohms (w/h/d, facluding projections)
VIDEO3 Phono 245 mV 47 kohms : Bey
PHONO (MM) | Phono 33mV 47 kohms
MIC Phone ImVv 10 kohms Design and specifications are subject to change without notice.
Audio output | Jack type Voltage Impedance
Abbreviations
VIDEO 1/MD_ | Phono 235 mV 2kohms G German model
VIDEO 2/DAT | Phono 235 mV 2 kohms IT: Italian model
CENTER OUT | Phono AUS: Australian model
EA : Saudi Arabia model
Nae 5 MY : Malaysia model
Video input (phono jacks) SP: Singapore model
VIDEO 1/MD, VIDEO 2/DAT, VIDEO 3 “TEs Le rganiat ehedal
1 Vp-p, 75 ohm unbalanced, sync WS Maca Badal
negative
Video output (phono jacks)
VIDEO 1/MD 1 Vp-p, 75 ohm unbalanced, syne
negative
VIDEO 2/DAT 1 Vp-p, 75 ohm unbalanced, sync
negative
MONITOR 1 Vp-p, 75 ohm unbalanced, syne
negative Le SAFETY-RELATED COMPONENT WARNING!!
Frequency response 15 Hz to 20 kHz" dB
Power requirements 220—230V AC, 50/60Hz
(AEP, G, IT, CIS)
240V AC, 50/60Hz (AUS)
110—120V/220—240V AC, 50/60Hz
(, EA, MY, SP, JE)
120V AC, 60Hz (MX)
COMPONENTS IDENTIFIED BY MARK /\ OR DOTTED LINE WITH
MARK /{\ ON THE SCHEMATIC DIAGRAMS AND IN THE PARTS LIST
ARE CRITICAL TO SAFE OPERATION. REPLACE THESE COMPONENTS
WITH SONY PARTS WHOSE PART NUMBERS APPEAR AS SHOWN IN
THIS MANUAL OR IN SUPPLEMENTS PUBLISHED BY SONY.
DIGITAL STEREO PREAMPLIFIER
SONY.

MODEL
IDENTIFICATION
TABLE
OF
CONTENTS
—Specitication
Label—
Section Title Page
SOTIME
piMCmeL
NOTA
AZO
1.
GENERAL
DIGITAL
STEREO
PREAMPLIFIER
1-1.
Location
of
Controls
.............
aa)
LZ
ZL
2. SERVICE NOTE
2-1. Removal of Joint ..... teeeeeaes ae wok ere
SERIAL NO.
MADE IN JAPAN | 3. DIAGRAMS
3-1, Pin Descriptions .
3-2. Circuit Boards Location ae F
3:3, Semiconductor Lead Layouts .. nee ceeen
AEP, IT, CIS model: AC: 220V—230V~50/60Hz 18W
G model : SYSTEM LBT-A790 i
AC: 220V-—-230V~50/60Hz 18W 3-4. Block Diagram ..... pete sre auN 10
AUS
model
:
AC:
240V~50/60Hz
18W
3-5.
Printed
Wiring
Boards—Main
Section—
Peer:
EEA, 3-6. Schematic Diagram —Main Section— .......... 17
MY,
SP,
JE
model
:
AC:
110V—120V/220V—240V~50/60Hz
18W
3:7.
Sch
ic
Di
—Panel
Section—
22
MX modo! : AG: 120V~60H2z 18W -7. Schematic Diagram anel Section— ...........
3-8. Printed Wiring Boards—Panel Section— . 27
® Abbreviations
IT: Italian model 4. EXPLODED VIEWS
Gs:
German
model
.
‘AUS: Australben rede 4-1. Front Panel Section ......... eee uhs ieatbeenee gS:
EA ; Saudi Arabia model 4-2, Chassis Section ......-.. Gea stars fans 34
MY : Malaysia model
SP : Sit
Sees eee 5. ELECTRICAL PARTS LIST ............0..0004 135
JE: Tourist model
MX : Mexican model

SECTION 1
GENERAL
This section is extracted from
1-1.
LOCATION
OF
CONTROLS
instruction
manual.
SOURCE DIRECT button and indicator
(96, 110)
POWER switch (20)
Numeric buttons (96, 100, 114, 116, 118)
Display window
MEMORY button (114, 118)
ENTER button and indicator (96, 106,
108, 118)
MODE button and indicator (96, 106,
108, 118)
= CURSOR CONTROL buttons (96, 106,
®@@ 108, 118)
|
---
z=
CANCEL
button
(106,
108)
VOLUME control (24)
BALANCE control (24, 98)
VIDEO 3 INPUT jacks (146)
DBS LEVEL and DBS FREQUENCY
buttons (24)
DISPLAY button (112)
Function selectors and indicators (42)
P. FUNCTION button and indicator
(144)
MIC LEVEL control (142)
HEADPHONES jack (22)
DSP MENU button and indicator (96,
100, 116)
&
IN|
2}
5S
je
=
12]
12)
IS)
i
we
fe
=
ala
Sy
a
lSI=lSIo)
fel
fig [13]
]
f
(slele)
SECTION 2
SERVICE NOTE
Note : Follow the disassembly procedure in the numerical order given.
2-1. REMOVAL OF JOINT
@ Press the joint for front panel and
remove if from POWER switch,
\
\ @ Remove the joint in the
| direction of arrow.
POWER switch ($701)
@ Push the button (POWER) and
POWER switch to turn ON.

3-1. PIN DESCRIPTIONS
@1C202 LC83015E (Digital Signal Processor)
SECTION 3
DIAGRAMS
Pin No.| Pin Name | 1/0 Function
1-6 | P0-P5 _| 1/0 | General purpose input/output ports (with pull-up resistor). Not used.
7 | ASI I | Audio data serial input 1 pin. “4
8 BCK1 1 | Bit clock input pin used for ASI1 input (64fs or 32fs is applied), aI
9 FS3841 1 | 384fs or 5124 input pin, Connect to GND. iat ail
10 LRCKI T | L/R channel identification signal input pin (“H” for Leh; “L” for Reh), Connect to GND.
ul ASI2_ 1 | Audio data serial input 2 pin. Connect to GND.
12 BCK2 1 | Bit clock input pin for ASI2 input (64fs or 32fs is applied). Connect to GND.
B VDD1 +5V power pin i
u4—17 [TESTI—TEST!| 1 | Pins used for tests, normally connected to GND.
18 VsS1 — [GND pin ;
19 TESTS © | Output pin used for test, normally open. Not used.
20 RAS © _| RAS signal output pin used for access to external DRAM.
21 CAS © | CAS signal output pin used for access to external DRAM.
22 DWRT O | Data write signal output pin used for access to external memory
23 DREAD O | Data read signal output pin used for access to external memory.
4 5 — | Not used.
25-32 | D7—D0 | I/O | Data input/output pins used for communication with external memories (D0—D3 for one
DRAM ; D0—D7 for two DRAMs or SRAM or pseudo SRAM).
3 vss2 — [GND pin ;
34-50 | A0—A16 | O | External memory address output pin.
51 VDD2 — | +5V power pin
52 OSCI I | Oscillator input pin (connected to VDD or VSS when oscillator is not used).
53 | OSC2 | O | Oscillator output pin (open when oscillator is not used or external clock is used). |
54 VSS3 — [GND pin
55 FS3840 © _| 384s or 512fs output pin (through output of FS384I or self-run oscillating clock). Not used.
56 FS1920 © | 192fs or 256fs output pin (1/2 frequency division output of FS3840). e
57 FS1280 © | 128%s output pin (1/3 or 1/4 frequency division output of FS3840). Not used.
58 FS640 | 64fs or 32fs output pin (1/2 frequency division output of F$1280 or through output of BCK1).
59 F320 O | 32fs or 16fs output pin (1/2 frequency division output of FS640). Not used.
60 LRCKO ©. | ifs output pin (1/64 frequency division output of FS640 or through output of LRCKD.
61 ~AOWCK | 0 | 2fs or Lfs output pin (1/32 frequency division output of FS640). Not used.
62 ‘ASO 0 _| Audio data serial output 1 pin.
63 AOTDF1 | © | Audio data serial output 2 pin, Not used. =
64 AOTDF2 © | Audio data serial output 3 pin. is =a
65 SI 1 | Input pin for serial data from control micro computer (8 bit data).
66 | SICK 1 | Input pin for serial clock for SI.
67 SIRQ 1 | Serial input request signal input pin.
68 SIAK O | Output pin for indicating that serial input being executed.
69 SRDY I | Input pin for ready signal indicating that serial data from control micro computer is complete.
70 sO O | Output pin for sending serial data to control micro computer (8 bit data). ae:
7 | SOCK T_| Input pin for serial clock for SO. = ioe
72 SORQ 1 | Input pin for serial output request signal.
73 | SOAK © | Output pin for indicating that serial output is being executed.

Pin No.| Pin Name | 1/0 Function
74 vss4 — | GND pin
iB RES I_ | reset pin (with pull-up resistor).
76 INT 1 | Interrupt request input pin (with pull-up reistor). Not used. -
71 VDD3 +5V power pin
78
SELC
|
I
|
Select
pin
(with
pull-down
resistor)
used
to
determine
whether
system
clock
of
L$83015
is
produced from F$384I (L) or from self-run oscillating clock (H).
79
SACK
T
|
Select
pin
(with
pull-down
resistor)
used
to
determine
whether
1/3
frequency
division
output
of F$3840 is used (L) or 1/4 frequency division output is used (H) as FS1280.
80
SACK?
I
|
Select
pin
(with
pull-down
resistor)
used
to
determine
whether
each
FS
output
clock
is
|
produced
from
FS384I,
LRCKI
and
BCK1
(L)
or
from
self-run
oscillating
clock
(H).
©1C501 PD78014CW-057 (System Control)
Pin No.| Pin Name | 1/0 Function
1 DSP SRDY | O | Serial*Handshake output to LC83015E (DSP).
2 DSP SI ©. | Serial-Data output to LC83015E.
3 DSP SICK | O_ | Serial+Clock output to LC83015E.
4
DSP
SIAK
I
_|
Serial-
Handshake-
Acknowledge
input
with
LC83015E.
Fr
5 DSP SIRQ | O | Serial-Handshake+Request to LC83015E. E
6-8 ae — | Not used.
9 LATCH2 | O | Latch output to TO9270F (Rear DAC).
10 INIT 0. | For Reset of LC83015E, CXD2564M and TC9270F.
u ATT O | Serial-Data output to CDX2564M and TC9270F.
5) SHIFT © | Serial-Clock output to CDX2564M and TC9270F.
1B LATCH! | O_ | Latch output to CXD2564M (Front DAC). :
4
CLK
©
|
Serial-Clock
output
to
LC7822
(Analog
SW)
and
LC7535
(E-Vol).
|
16 DATA © | Serial-Data output to LC7822 and LC7535,
16 CE | Chip-Enable output to LC7822 and LC7535.
7
vss
—
|
Microcomputer-GND
pin.
;
18—20 = — | Not used
21 GAIN2DB | O_ | For Front analog+Gain adjustment. ( “L” is +2dB.)
22 GAIN4DB_ | O | For Front analog-Gain adjustment. ( “L” is +44B.)
23 GAINSDB | O | For Front analog-Gain adjustment. ( “L” is +84B.)
24
PD
10
_|
For
Offset
calibration
of
AK5369-VP,
(At
POWER
ON,
for
200msec_*H”
.)
| 25, 26 = — | Not used.
27
|
RECLEVEL
|
0
|
At
increase
more
than
6dB
for
EQ
on
“L”
,
to
control
output
voltage
to
deck.
28
MUTEB-R
|
O_
|
Mute
of
surround
ch
selection
(-1
+
2-2),
At
mute
“L”
29 P. MUTE | O | Power-AMP mute control of Power ON/OFF. At mute “L” .
30
MUTEB-F
|
©
|
Mute
(Front)
of
Power
ON/OFF.
At
mute
“L”
.
‘
31 — [| — [Not used.
[2 vss — | Microcomputer-GND pin. :
33,
34
= —
|
Not
used.
;
35
SURR
O
|
Surround
ch
selection
(3-1
“L”
=
2-2
“H”
)
=
36 RECOB © | At the Function is VIDEO 1 “L” , cut the output to VIDEO 1.
37 RECOA © | At the Function is VIDEO 2 “L” , cut the output to VIDEO 2.
38
DOLBY
©
|
At
the
DOLBY
PRO-LOGIC
“L”
,
set
the
DOLBY
B
for
surround
output.
3942 = — | Not used.

Pin No.| Pin Name | 1/0 Function
B RESET | — | Microcomputer-Reset pin
44 MREQ I | Communication request from ~PD78014CW-065.
45 SREQ 0 | Acknowledge output to wPD78014CW-065.
46 MCLK 1_| Serial-Clock from ~PD78014CW-065.
47 | MDATA | 1 _| Serial-Data from ¢PD78014CW-065.
48 vob _| — | Microcomputer+5V power supply pin.
49 x2 — | System clock connection pin
50 X1___ | — [System clock connection pin
5 IC (VPP) _| — | Inner connection (Connect to GND.)
52 XT2 — | Not used.
53 Pod/XT1 | I | Connect to GND.
54 AVSS — | Connect to GND.
55 INH 0. | Audio+Function output (See Fig. 1)
56 FUNCB O | Audio+Function output (See Fig. 1)
57 FUNCA [0 | Audio-Function output (See Fig. 1)
58 VIDEO-A__| 0 | Visual+Function output (See Fig. 2.)
59 VIDEO-B__| 0 | Visuai+Function output (See Fig. 2.)
60 MUTEA | O | Amplifier mute pin. At mute “H’ .
61, 62 = —_[ Not used.
63 AVDD_ — | Connect to 5V power supply.
64 AVREF | — | Connect to GND.
pp\ | VIDEO 1] VIDEO 2| VIDEO 3) TAPE | CD | TUNER | PHONO
55 L H L H H E ‘L
36 | H H H L L L L
s7 | A H L i H L H
- Fig. 1
p)\ | VIDEO 1] VIDEO 2| VIDEO 3
eb oe H L
39 | oL a H
Fig. 2

@1C601 .PD78014CW-065 (SYSTEM CONTROL)
Pin No.| Pin Name | 1/0 Function
1 FLLATCH | 0 | Latch output to TD62C950RF (FLT-driver).
2 FLDATA | 0 | Serial-Data output to TD62C950RF.
3 FLCLK | © | Serial+Clock output to TD62C950RF.
4 FLCLR | 0 | Serial+Clear output to TD62C950RF.
5
|
DSPSORG
|
0
|
Serial-Handshake-Request
output
to
LC83015E.
s
6 DSP SO | O | Serial-Data output to LC83015E.
7 = —_| Not used.
8 | DSPSOCK | 0 |Serial*Clock output to LC83015E.
9 DSP SOAK | I | SerialsHandshake Acknowledge input from LC83015E.
10 | MREQ O | Communication request to »PD78014CW-057.
[ 1 | SREQ I | Acknowledge input from PD78014CW-057.
rr) MCLK 0 _| Serial-Clock to ~PD78014CW-057.
B MDATA | 0 | Serial-Data to ¢PD78014CW-057.
u—17 = — | Connect to GND.
18 KEY-01 | O_ | Keyscan & LED Digit 1
19 KEY-02 | O | Keyscan & LED Digit 2 7
20 KEY-03 | O | Keyscan & LED Digit 3
a KEY-01 | O | Keyscan & LED Digit 4 :
22 KEY-O1 O | Keyscan & LED Digit 5 7
23-25 = —_| Not used. ;
26 LEDI © [LED Scan Segment 1
27 LED2 0 | LED Scan Segment 2
28 LED3 O | LED Scan Segment 3
29-31 - — | Connect to GND. 7
32 vss —_ | Microcomputer+GND pin.
33 VOLLED | 0 | Volume LED ON/OFF.
34—40 = — | Connect to GND.
41
AuBOUT
|
0
|
AU
BUS
output
=
2 = — | Connect to GND.
43
1
|
Reset
input
a
44 accuT | 1 [ACCUT
45 AUB IN 1 | AU BUS IN
46 | VOL DOWN | O | Volume Down ;
a7 VoL UP | O | Volume Up i
48 VDD VDD _
9 X2 — | Crystal connection pin of system clock oscillation. 7
50 x1 Crystal connection pin of system clock oscillation.
Bl IC — | Connect to GND. 7
52 eat — | Not used.
53,
54
=
—
|
Connect
to
GND.
x
55 VOL LOC | 1 | Volume position
56 KEY-IL I_ | Keyscan IN 1
57 | PEY-I2 I | Keyscan IN 2 i
58 KEY-13 I_| Keyscan IN 3
| 59 KEY-I4 1 [Keyscan IN 4

Pin No.| Pin Name | 1/0 Funetion
60 KEY-15 T_| Keyscan IN 5
él KEY-I6 1_| Keyscan IN 6
|
62
KEY-I7
I
|
Keyscan
IN
7
=
63 ~ AVDD — | vpp
64
AVREF
|
VDD
(reference)
_
ei
3-2. CIRCUIT BOARDS LOCATION
VOLTAGE SELECTION board (E, EA, MY, SP, JE)
MAIN board
VIDEO FUNCTION board
AU FUNCTION board
PANEL
board
VOL
board
VIDEO 3 board BALANCE board