Sony STR-K785 Service Manual

STR-K785

SERVICE MANUAL

Ver. 1.2 2007.07

• STR-K785 is the tuner and the amplifier
section in HT-DDW785 and HTP-78DW .

Manufactured under license from Dolby Laboratories.
“Dolby”, “Pro Logic” and the double-D symbol are trademarks of
Dolby Laboratories.
“DTS” and “DTS Digital Surround” are registered trademarks of
Digital Theater Systems, Inc.

SPECIFICATIONS

Amplifier section

Power Output
Models of area code SP and SP6
Stereo mode (rated) (6 ohms 1 kHz, THD 1%)

Surround mode
THD 10%)

Models of area code AUS
Stereo mode (rated) (6 ohms 120 Hz – 20 kHz,
THD 0.09%)

Stereo mode (rated) (6 ohms 1 kHz, THD 1%)

Surround mode
THD 10%)

Models of area code AEP

Stereo mode (rated) (6 ohms, 1 kHz, TH D 1%)

1)

70 W + 70 W

2)

(reference) (6 ohms 1 kHz,

RMS output
FRONT: 100 W per
channel
CENTER: 100 W
SURROUND: 100 W per
channel

50 W + 50 W

85 W + 85 W

2)

(reference) (6 ohms 1 kHz,

RMS output
FRONT: 122 W per
channel
CENTER: 122 W
SURROUND: 122 W per
channel

85 W + 85 W

Surround mode
THD 10%) RMS output

1)

Measured under the following conditions:

Area code Power requirements

SP, SP6 230 V AC, 50 Hz
AUS 240 V AC, 50 Hz
AEP 230 V AC, 50 Hz

2)

Reference power output for front, center and
surround speakers. Depending on the sound field
settings and the source, there may be no sound
output.

Inputs
Analog Sensitivity: 800 mV/

Digital (Coaxial) Impedance: 75 ohms
Outputs (Analog)
SUB WOOFER Voltage: 2 V/1 kohm
Tone
Gain levels ±6 dB, 1 dB step
Reproduction frequency range:

2)

(reference) (6 ohms, 1 kHz,

FRONT:122 W
per channel

CENTER:122 W
SURROUND:122 W

per channel

50 kohms

28 – 20,000 Hz

AEP Model

E Model

Australian Model

FM tuner section

Tuning range 87.5 - 108.0 MHz
Antenna FM wire antenna
Antenna terminals 75 ohms, unbalanced
Intermediate Frequency

10.7 MHz

AM tuner section

Tuning range
With 9-kHz tuning scale:

531 - 1,602 kHz
Antenna Loop antenna
Intermediate Frequency

450 kHz

Video section

Inputs/Outputs

Video: 1 Vp-p, 75 ohms
COMPONENT VIDEO:

Y: 1 Vp-p, 75 ohms

B/CB

: 0.7 Vp-p,

P

75 ohms

R/CR

: 0.7 Vp-p,

P

75 ohms

80 MHz HD Pass Through

— Continued on next page —

MULTI CHANNEL AV RECEIVER

9-887-648-03

2007G16-1
© 2007.07

Sony Corporation

Home Audio Division
Published by Sony Techno Create Corporation

STR-K785

CENTER FRONT

LR

LR

+ +

Ver. 1.2

General

Power requirements

Area code Power requirements

AUS 240 V AC, 50 Hz
SP, SP6 230 – 240 V AC, 50/60 Hz
AEP

230 V AC, 50/60 Hz

Power consumption

Area code Power consumption

AUS/AEP
SP, SP6 170 W

190 W

Power consumption (during standby mode)

0.3 W

Dimensions (w/h/d) (Approx.)

430 × 145 × 300 mm
including projecting parts

and controls

Mass (Approx.) 7.5 kg

Design and specifications are subject to
change without notice.

• Abbreviation
AUS : Australian model
SP : Singapore model
SP6 : Singapore and Malaysia models

Notes on chip component replacement

• Never reuse a disconnected chip component.

• Notice that the minus side of a tantalum capacitor may be

damaged by heat.

UNLEADED SOLDER

Boards requiring use of unleaded solder are printed with the lead­free mark (LF) indicating the solder contains no lead.
(Caution: Some printed circuit boards may not come printed with

the lead free mark due to their particular size)

: LEAD FREE MARK

Unleaded solder has the following characteristics.

• Unleaded solder melts at a temperature about 40 °C higher

than ordinary solder.
Ordinary soldering irons can be used but the iron tip has to be
applied to the solder joint for a slightly longer time.
Soldering irons using a temperature regulator should be set to
about 350 °C.
Caution: The printed pattern (copper foil) may peel away if

the heated tip is applied for too long, so be careful!

• Strong viscosity

Unleaded solder is more viscou-s (sticky, less prone to flow)
than ordinary solder so use caution not to let solder bridges
occur such as on IC pins, etc.

• Usable with ordinary solder

It is best to use only unleaded solder but unleaded solder may
also be added to ordinary solder.

About area codes

The area code of the receiver you purchased is
shown on the lower right portion of the rear panel
(see the illustration below).

Area code

Any differences in operation, according to the area
code, are clearly indicated in the text, for example,
“Models of area code AA only”.

MODEL IDENTIFICATION
– Rear Panel –

Parts No.

Model Part No.

SP and SP6 models 2-662-452-3[]
AUS model 2-662-452-4[]
AEP model 2-662-452-5[]

SAFETY-RELATED COMPONENT WARNING!!

COMPONENTS IDENTIFIED BY MARK 0 OR DOTTED LINE
WITH MARK 0 ON THE SCHEMATIC DIAGRAMS AND IN
THE PARTS LIST ARE CRITICAL TO SAFE OPERATION.
REPLACE THESE COMPONENTS WITH SONY P ARTS WHOSE
PART NUMBERS APPEAR AS SHOWN IN THIS MANUAL OR
IN SUPPLEMENTS PUBLISHED BY SONY.

2

TABLE OF CONTENTS

1. GENERAL ................................................................... 4

2. TEST MODE ............................................................... 10

3. ELECTRICAL ADJUSTMENT ............................. 12

4. DIAGRAMS

4-1. Block Diagram – MAIN Section –.................................. 14

4-2. Block Diagram – DISPLAY/POWER Section – ............. 15

4-3. Printed Wiring Board – DIGITAL Board (Side A) –...... 16

4-4. Printed Wiring Board – DIGITAL Board (Side B) –...... 17

4-5. Schematic Diagram – DIGITAL Board (1/3) – .............. 18

4-6. Schematic Diagram – DIGITAL Board (2/3) – .............. 19

4-7. Schematic Diagram – DIGITAL Board (3/3) – .............. 20

4-8. Printed Wiring Board – MAIN Board – ......................... 21

4-9. Schematic Diagram – MAIN Board (1/3) – ................... 22

4-10. Schematic Diagram – MAIN Board (2/3),

HEADPHONE Board –................................................... 23

4-11. Schematic Diagram – MAIN Board (3/3),

ADCC Board, STANDBY Board – ................................. 24

4-12. Printed Wiring Boards

– ADCC Board, HEADPHONE Board – ........................ 25

4-13. Printed Wiring Board – STANDBY Board – ................. 26

4-14. Printed Wiring Board – DISPLAY Board – ................... 27

4-15. Printed Wiring Boards

– TUNING Board, POWER Board – .............................. 28

4-16. Schematic Diagram – DISPLAY Board,

TUNING Board, POWER Board – ................................. 29

4-17. Printed Wiring Board – VIDEO Board –........................ 30

4-18. Schematic Diagram – VIDEO Board – .......................... 31

STR-K785

5. EXPLODED VIEWS

5-1. Front Panel Section ......................................................... 39

5-2. Chassis Section................................................................ 40

6. ELECTRICAL PARTS LIST .................................. 41

3

STR-K785

Receiver

Front panel

SECTION 1

GENERAL

This section is extracted
from instruction manual.

1 2 3 6 7 8

?/1

AUTO CAL MIC

PHONES

MEMORY

FM MODE TUNING

DISPLAY DIMMER

PRESET TUNING

4

+

+

VIDEO 1 VIDEO 2 DVD SA-CD/CD FM AM

5

AMP MENU ENTER MASTER

INPUT MODE

qjqkqlw; qgqh qf qaq;qsqd

Name Function

A ?/1 Press to turn the receiver

on or off (page 23, 30, 31,

44).

B DISPLAY Press to select information

displayed on the display
(page 50).

C DIMMER Press to adjust the

brightness of the display.

D Remote sensor Receives signals from

remote commander.

E Display The current status of the

selected component or a
list of selectable items
appears here (page 6).

F 2CH Press to select 2CH

STEREO mode (page 38,

44).

G A.F.D. Press to select A.F .D. mode

(page 41).

H MOVIE,

MUSIC

I MASTER

VOLUME

J ENTER Press to store a station or

Press to select sound fields
(MOVIE, MUSIC) (page

42).
Turn to adjust the volume

level of all speakers at the
same time (page 28, 29,
30, 31).

enter the selection when
selecting the settings
(page 23, 26, 27, 32, 48,

49).

Name Function

K INPUT MODE Press to select the input

mode when the same
components are connected
to both digital and analog
jacks

L I/i/U/u After pressing AMP

MENU (M), press I or i
and U or u to select the
settings.

M AMP MENU Press to display the menu

of the receiver.

N Input buttons Press one of the buttons to

select the component you
want to use.

O PRESET

TUNING +/–

P TUNING +/– Press to scan a station.
Q MEMORY Press to store a station.
R FM MODE Press to select FM

S PHONES jack Connects to a headphone

T AUTO CAL MIC

jack

Press to select a preset
station.

monaural or stereo
reception.

(page 55).
Connects to the supplied

optimizer microphone for
the Auto Calibration
function (page 24).

2CH A.F.D. MOVIE MUSIC

VOLUME

9

(page 49).

4

About the indicators on the display

214356 7

STR-K785

SW

LFE

SP

DIGITAL

;

;

PRO LOGIC II

SLEEP OPT COAX

L C R

SLSSR

qaqs

qf

Name Function

A SW Lights up when audio signal is

B LFE Lights up when the disc being

C SP Lights up when the receiver is

D ;DIGITAL Lights up when Dolby Digital

E ; PRO

LOGIC (II)

F DTS Lights up when DTS signals are

G MEMORY Lights up when a memory

output from the SUB WOOFER
jack.

played back contains an LFE
(Low Frequency Effect)
channel and the LFE channel
signal is actually being
reproduced.

turned on. This indicator does
not light up if a headphone is
connected to the PHONES jack.

signals are input.

Note

When playing a Dolby Digital
format disc, be sure that you
have made digital connections
and that INPUT MODE is not
set to “ANALOG” (page 49).

“; PRO LOGIC” lights up
when the receiver applies Pro
Logic processing to 2 channel
signals in order to output the
center and surround channel
signals. “; PRO LOGIC II”
lights up when the Pro Logic II
Movie/Music decoder is
activated.

Note

Dolby Pro Logic and Dolby Pro
Logic II decoding do not
function for DTS format
signals.

input.

Note

When playing a DTS format
disc, be sure that you have made
digital connections and that
INPUT MODE is not set to
“ANALOG” (page 49).

function, such as Name Input,
Preset Memory (page 47), etc.,
is activated.

DTS

MEMORY

STEREO MONOD.RANGE

q; 9qd

8

Name Function

H Preset

station
indicators

I Tuner

indicators

J D.RANGE Lights up when dynamic range

K COAX Lights up when INPUT MODE

L OPT Lights up when INPUT MODE

M SLEEP Lights up when the Sleep Timer

N Playback

channel
indicators

L
R
C
SL
SR
S

Lights up when using the
receiver to tune in radio stations
you have preset. For details on
presetting radio stations, see
page 46.

Lights up when using the
receiver to tune in radio stations
(page 45), etc.

compression is activated (page

33).

is set to “ A UTO” and the source
signal is a digital signal being
input through the COAXIAL
jack, or when INPUT MODE is
set to “COAX IN” (page 49).

is set to “ A UTO” and the source
signal is a digital signal being
input through the OPTICAL
jack, or when INPUT MODE is
set to “OPT IN” (page 49).

function is activated (page 50).
The letters (L, C, R, etc.)

indicate the channels being
played back. The boxes around
the letters vary to show ho w the
receiver downmixes the source
sound.
Front Left
Front Right
Center (monaural)
Surround Left
Surround Right
Surround (monaural or the
surround components obtained
by Pro Logic processing)

Example:

Recording format (Front/
Surround): Dolby Digital 3/2.1
Sound Field: A.F.D. AUTO

SW LFE

L C R

SL SR

5

STR-K785

Rear panel

DIGITAL

OPTICAL

VIDEO 1

IN

VIDEO 2

IN

DVD IN

COAXIAL

2

ANTENNA

L

R

AUDIO IN

SA-CD/CD

AM

3

VIDEO IN VIDEO IN

L

R

AUDIO IN

AUDIO IN

DVD

VIDEO 2

L

R

AUDIO IN

VIDEO 1

A DIGITAL INPUT section

OPTICAL
IN jacks

COAXIAL IN
jack

Connects to a DVD
player, etc. The
COAXIAL jack
provides a better
quality of loud
sound (page 18,

20).

VIDEO IN

MONITOR

VIDEO OUT

AUDIO

OUT

SUB

WOOFER

41

DVDINVIDEO 2INMONITOR

OUT

COMPONENT VIDEO

Y

B/CB

P

PR/C

R

LR

+ +

LR

SURROUND

SPEAKERS

+ +

CENTER FRONT

LR

LR

56

D COMPONENT VIDEO INPUT/

OUTPUT section

Green

Blue

Red

COMPONENT
VIDEO
INPUT/
OUTPUT
jacks*

Connects to a DVD
player, TV, or a
satellite tuner. You
can enjoy high
quality image
(page 17, 19, 20).

B ANTENNA section

FM
ANTENNA
jack

AM
ANTENNA
terminals

Connects to the
FM wire antenna
supplied with this
receiver (page 22).

Connects to the
AM loop antenna
supplied with this
receiver (page 22).

C VIDEO/AUDIO INPUT/OUTPUT

section

White (L)

Red (R)

Yellow

AUDIO IN
jacks

VIDEO IN/
OUT jacks*

Connects the video
and audio jacks of
a VCR or a DVD
player (page 15,
17, 18, 19, 20, 21).

E SPEAKERS section

Connects to the
speakers (page 14).

Connects to the
sub woofer (page

14).

F AUDIO INPUT section

White (L)

AUDIO IN
jacks

Red (R)

*You can watch the selected input image when you

connect the MONITOR OUT jack to a TV (page

17).

Connects to a CD
player, etc. (page

15).

6

STR-K785

Remote commander

You can use the supplied remote RM-AA U006
to operate the receiv er and to control the Sony
audio/video components that the remote is
assigned to operate (page 51).

1

TV

TV/VIDEO

SLEEP

wg
wf

VIDEO 1 VIDEO 2 DVD SA-CD/CD

wd

ws

wa

w;

2CH A.F.D.

123
46
78

>10/

-

CLEAR

ql

qk

qj

Gg

RETURN/EXIT

TV CH –

REPLAY ADVANCE

PRESET –

.

TUNING –

TV

qh

AUTO

CAL

5

0/10

F

f

<

HmM

Xx

?/1

AV

?/1

?/1

SYSTEM STANDBY

TUNER

AMP MENU

MOVIE MUSIC

DUAL MONO

FM MODE

D.TUNING

9

D.SKIP

MEMORY DVD MENU

ENTER

MUTING

TOOLSDISPLAY

TV VOL

MASTER VOL

MENU

TV CH +

PRESET +

<

>

TUNING +

2

3

4
5

6

7

8
9

q;
qa
qs

qd

qf

qg

Name Function

A AV ?/1

(on/standby)

B TV ?/1

(on/standby)

?/1
(on/standby)

C Input buttons Press one of the buttons to

Press to turn on or off the
Sony audio/video components
that the remote is assigned to
operate.
If you press ?/1 (B) at the
same time, it will turn off the
receiver and other
components (SYSTEM
STANDBY).

Note

The function of the AV ?/1
switch changes automatically
each time you press the input
buttons (C).

Press TV ?/1 and TV (P) at
the same time to turn the TV
on or off.

Press to turn the receiver on or
off.
To turn off all components,
press ?/1 and AV ?/1 (A) at
the same time (SYSTEM
STANDBY).

select the component you
want to use. When you press
any of the input buttons, the
receiver turns on. The buttons
are factory assigned to control
Sony components as follows.
You can change the button
assignments following the
steps in “Changing button
assignments” on page 51.

Button Assigned Sony

component

VIDEO 1 VCR (VTR mode 3)
VIDEO 2 VCR (VTR mode 2)
DVD DVD player
SA-CD/CD Super Audio CD/CD

player

TUNER Built-in tuner

D AMP MENU Press to display the menu of

the receiver. Then, use V, v,
B, b and to perform menu
operations.

E MOVIE,

MUSIC

Press to select sound fields
(MOVIE, MUSIC).

7

STR-K785

Name Function

F DUAL MONO Press to select the language

you want during digital
broadcast.

G FM MODE Press to select FM monaural

or stereo reception.

H D.TUNING Press to enter direct tuning

mode.

D.SKIP Press to skip disc of the CD

player or DVD player (multi­disc changer only).

I ENTER Press to enter the value after

selecting a channel, disc or
track using the numeric
buttons of the TV, VCR or
satellite tuner.

MEMORY Press to store a station.

J DVD MENU Press to display the menu of

the DVD player on the TV
screen. Then, use V, v, B, b
and to perform menu
operations.

K TOOLS Press to display options

applicable to the entire disc
(e.g. disc protection), recorder
(e.g. audio settings during
recording), or multiple items
on a list menu (e.g. erasing
multiple titles).

L MUTING Press to mute the sound.
M TV VOL

+*/–

MASTER VOL
+*/–

N MENU Press to display the menus of

Press TV VOL +/– and TV
(P) at the same time to adjust
the TV volume level.

Press to adjust the volume
level of all speakers at the
same time.

the VCR, DVD player, or
satellite tuner on the TV
screen. Then, use V, v, B, b
and to perform menu
operations.

Name Function

O ./> Press to skips tracks of the CD

player, DVD player, or tape
deck.

REPLAY /
ADVANCE

m/M Press to

H* Press to start playback of the

X Press to pause playback or

x Press to stop playback of the

TV CH +/– Press TV CH +/– and TV (P)

PRESET +/– Press to select

TUNING +/– Press to scan a station.

P TV Press TV and the button you

Q RETURN/

EXIT O

<

Press to replay the previous

<

scene or fast forward the
current scene of the VCR or
DVD player.

–search tracks in the forward/

backward direction of the
DVD player.

–fastforward/rewind of the

VCR, CD player, or tape
deck.

VCR, CD player, D VD player,
or tape deck.

recording of the VCR, CD
player, DVD player, or tape
deck. (Also starts recording
with components in recording
standby.)

VCR, CD player, D VD player,
or tape deck.

at the same time to select
preset TV channels.

–preset stations.
–preset channels of the VCR

or satellite tuner.

want at the same time to
activate the buttons with
orange printing.

Press to
–return to the previous menu.
–exit the menu while the

menu or on-screen guide of
the VCR, DVD player, or
satellite tuner is displayed
on the TV screen.

8

Name Function Name Function

STR-K785

R , V/v/B/b After pressin g AMP MENU

(D), DVD MENU (J), or
MENU (N), press V, v, B or
b to select the settings. When
you press DVD MENU or
MENU, press to enter the
selection.

S DISPLAY Press to select the information

displayed on the TV screen of
the VCR, satellite tuner, CD
player or DVD player.

T -/-- Press -/-- and TV (P) at the

same time to select the
channel entry mode, either
one or two digits of the TV.

x

>10/

CLEAR Press to

U Numeric

buttons
(number 5*)

V 2CH Press to select 2CH STEREO

W A.F.D. Press to select A.F.D. mode.
X AUTO CAL Press to activate the Auto

Press to select
–track numbers over 10 of the

VCR, satellite tuner or CD
player.

–channel numbers of the

Digital CATV terminal.

–clear a mistake when you

press the incorrect numeric
buttons.

–return to continuous

playback, etc. of the satellite
tuner or DVD player.

Press to
–preset/tune to preset

stations.

–select track numbers of the

CD player or DVD player.
Press 0/10 to select track
number 10.

–select channel numbers of

the VCR or satellite tuner.
Press the numeric buttons and
TV (P) at the same time to
select the TV channels.

mode.

Calibration function.

Y TV/VIDEO Press TV/VIDEO and TV

(P) at the same time to select
the input signal (TV input or
video input).

SLEEP Press to activate the Sleep

Timer function and the
duration which the receiver
turns off automatically.

*The number 5, MASTER VOL +, TV VOL +, and

H buttons have tactile dots. Use the tactile dots as
references when operating the receiver.

Notes

Some functions explained in this section may not

work depending on the model.

The above explanation is intended to serve as an

example only. Therefore, depending on the
component, the above operation may not be
possible or may operate differently than described.

9

STR-K785

SPK Front Left

DCAC MIC

Receiver

SECTION 2

TEST MODE

SOUND FIELD CLEAR MODE

The preset sound field is cleared when this mode is activated. Use
this mode before returning the product to clients upon completion
of repair.

Procedure:

1. While depressing the 2CH button, press the power ?/1
button to turn on the main power.

2. The message “S.F. CLR.” appears and initialization is
performed. (3 second)

SOFTWARE VERSION DISPLAY MODE

The software version is displayed.

Procedure:

1. While depressing the PRESET TUNING – and the < buttons
simultaneously, press the power ?/1 button to turn on the
main power.

2. The model name, destination and the software version are
displayed. (8 second)

KEY CHECK MODE

Button check

Procedure:

1. While depressing the < and the A.F.D. buttons simulta­neously, press the power ?/1 button to turn on the main
power.
“REST 25” appears.

2. Every pressing of any button other than ?/1 counts down
the buttons. The buttons which are already counted once are
not counted again.

3. When all buttons are pressed “REST 00” appears.

FLUORESCENT INDICATOR TUBE TEST MODE

All fluorescent segments are tested. When this test is acti v a ted, all
segments turn on at the same time, then each segment turns on one
after another.

Procedure:

1. While depressing the PRESET TUNING – and the AM
buttons simultaneously, press the power ?/1 button to turn
on the main power.

2. All segments turn on.

kHz
mft.
MHz

MEMORY

DIRECT

dB

LFE

SW

L

CR

SL S SR

SBL SB SBR

SP A

D

D

D

SP B SLEEP OPT COAX MULTI CH IN 96/24

D

DIGITALEX PRO LOGIC II x DTS-ES NEO:6 MPEG-2 AAC RDS

D.RANGE EQ STEREO MONO

SWAP ALL MODE

Procedure:

1. While depressing the PRESET TUNING – and the A.F.D.
buttons simultaneously, press the power ?/1 button to turn
on the main power.

2. “SWP.ALL” appears. (No change while displayed.)

SHIPMENT MODE

All preset contents are reset to the default setting.

Procedure:

1. While depressing the AM and the A.F.D. buttons simulta­neously, press the power ?/1 button to turn on the main
power.

2. “CLEARED” appears and switch off the set.

PROTECTOR

If an error occurs, the “Protector Display” will flash for a while and
the power is turned OFF.

Procedure:

1. While depressing the PRESET TUNING – and the 2CH
buttons simultaneously, press the power ?/1 button to turn
on the main power.

2. “PROT. EVER” appears (3 seconds) and the display returns
to the “Protector Display” and the power remains ON.

VACS CONTROL

Procedure:

1. While depressing the < and the DIMMER buttons simulta­neously, press the power ?/1 button to turn on the main
power.

2. “VACS OFF” appears. (8 second)

DCAC FACTORY TEST MODE

DCAC Factory Test mode have two stages:

1. DCAC DSP Data Line Checking

2. DCAC board Checking

Start Pass Pass

DSP Data Line

Check

Factory Test System Setup

Auto Cal Mic

Check

END

3. Press either of the VIDEO1 or VIDEO2 or DVD or

4. Press either of the VIDEO1 or VIDEO2 or DVD or

5. Press either of the VIDEO1 or VIDEO2 or DVD or

10

SA-CD/CD or FM or AM button.

kHz
mft.
MHz

MEMORY

DIRECT

dB

LFE

LSWR

S

SB

SP A

D

D

D

SP B SLEEP OPT COAX MULTI CH IN 96/24

D

DIGITALEX PRO LOGIC II x DTS-ES NEO:6 MPEG-2 AAC RDS

D.RANGE EQ STEREO MONO

SA-CD/CD or FM or AM button once again.

kHz
mft.
MHz

MEMORY

DIRECT

C

SL SR

SBL SBR

SP A

D

D

D

SP B SLEEP OPT MULTI CH IN 96/24

D

DIGITALEX PRO LOGIC II x DTS-ES NEO:6 MPEG-2 AAC RDS

D.RANGE EQ STEREO MONO

SA-CD/CD or FM or AM b utton once again. All segments
turn off.

1. When power off :
Press the three buttons < + DISPLAY + ?/1 .
(If it doesn’t operate, please press DISPLAY again afetr 2
seconds.)
Afterward, press the DIMMER to start DCAC factory test
mode.

1. DCAC DSP Data Line Checking

After press the DIMMER , DCAC Factory test mode will start,
below display will show:

“DCAC[][][]x” x = 1, 2, 3
If there is error happen, below display will show:

“ERR[]SD0x” x = 1 → D1112 or R1198 problem

x = 2 → D1113 problem
x = 3 → D1114 problem

2. DCAC board Checking

Connect front left speaker of the receiver and AUTO CAL
microphone. Turn MASTER V OLUME jog, there will be test tone
sound output from front left speaker, and the display will change
accordingly.

“AD[]-[]xxx” xxx = 0 to 255 (depends on loudness of test tone)

STR-K785

11

STR-K785

TUNER SECTION

[FM Auto Stop Check]

SECTION 3

ELECTRICAL ADJUSTMENT

generator

SET

Procedure:

1. Turn the power on.

2. Input the following signal from Signal Generator to FM
antenna input directly.

* Carrier Freq: A = 87.5 MHz, B = 98 MHz, C = 108 MHz

Deviation : 75 kHz
Modulation : 1 kHz
ANT input : 35 dBu (EMF)

Note: Please use 75 ohm “coaxial cable” to connect SG and the set. You

cannot use video cable for checking.
Please use SG whose output impedance is 75 ohm.

3. Set to FM tuner function and scan the input FM signal with
automatic scanning.

4. Confirm that input Frequency of A, B and C are detected and
automatic scanning stops.

OUT (75

Ω

)

The stop of automatic scanning means “The station signal is received
in good condition.”

12

SECTION 4

DIAGRAMS

STR-K785

Ver. 1.2

THIS NOTE IS COMMON FOR PRINTED WIRING BOARDS AND SCHEMATIC DIAGRAMS.
(In addition to this, the necessary note is printed in each block.)

For Schematic Diagrams.
Note:

• All capacitors are in µF unless otherwise noted. (p: pF)
50 WV or less are not indicated except for electrolytics and
tantalums.

• All resistors are in Ω and 1/
specified.

• % : indicates tolerance.

• f : internal component.

• 2 : nonflammable resistor.

• 5 : fusible resistor.

• C : panel designation.
Note: The components identified by mark 0 or dotted

line with mark 0 are critical for safety.
Replace only with part number specified.

• A : B+ Line.

• B : B– Line.

•Voltages and waveforms are dc with respect to ground un­der no-signal (detuned) conditions.
No mark : FM

•Voltages are taken with a VOM (Input impedance 10 MΩ).
Voltage variations may be noted due to normal production
tolerances.

•Waveforms are taken with a oscilloscope.

• Circled numbers refer to waveforms.

• Signal path.

F : FM
J : ANALOG
c : DIGITAL
I : VIDEO

• Abbreviation
AUS : Australian model
SP : Singapore model
SP6 : Singapore and Malaysia models

4

W or less unless otherwise

For Printed Wiring Boards.
Note:

• X : parts extracted from the component side.

• a: Through hole.

• f : internal component.

• : Pattern from the side which enables seeing.
Caution:

Pattern face side: Parts on the pattern face side seen from
(Side B) the pattern face are indicated.
Parts face side: Parts on the parts face side seen from
(Side A) the parts face are indicated.

• Indication of transistor.

C
Q

B

E

B

These are omitted.

CE

These are omitted.

• Circuit Boards Location

STANDBY board

POWER board

VIDEO board

DIGITAL board

ADCC board

TUNING board

HEADPHONE board

DISPLAY board

MAIN board

•Waveforms
– DIGITAL Board –

1

IC1501 9 (MCLK1)

72 ns

1 V/DIV, 40 ns/DIV

2

IC1101 id (X1)

41.6 ns

1 V/DIV, 20 ns/DIV

3

IC1301 ws (XIN)

3.4 Vp-p

4.2 Vp-p

STR-K785

81 ns

4.4 Vp-p

1 V/DIV, 40 ns/DIV

1313

STR-K785

Ver. 1.1

4-1. BLOCK DIAGRAM – MAIN SECTION –

ANTENNA

TN1

FM

75 Ω

COAXIAL

AM

TUNER PACK

FM

AM

FM SIG OUT

ST-DO

ST-DI

STEREO

TUNED

MUTING

RDS INT

RDS DATA

L CH

R CH

CLK

CE

• R-CH is omitted due to same as L-CH.

• Signal Path

: FM

: ANALOG

: DIGITAL

R-CH
TUNER +10V10V

IC400

ANALOG SOUND

PROCESSOR

10

IC1101(1/3)

SYSTEM CONTROLLER

73

DO

17

TUNER-DATA

16

T.SERIAL CLK

74

SLATCH

76

STEREO

75

78

43

52

53

TUNED

MUTE

RDS SIG

RDS CLK

RDS DATA

VIDEO 1

AEP

VIDEO 2

DVD

SA-CD/CD

COAXIAL

DIGITAL

OPTICAL

OPTICAL

J2000

AUTO CAL MIC

AUDIO IN

AUDIO IN

AUDIO IN

AUDIO IN

DVD

IN

VIDEO 1

IN

VIDEO 2

IN

IC2000(1/2)

57

J402

J400

J1301

IC1352

OPTICAL

IN

IC1353

OPTICAL

IN

IC2000(2/2)

3

IC1401

AD CONVERTER

LIN

IC1301

DIGITAL AUDIO

93

XSTATE

XMODE

CKSEL1

5

3

4

35

36

38

37

34

17

48

47

I/F RECEIVER

DIN2

DIN0

DIN1

DO

DI

CLK

CE

ERROR

XSTATE

XMODE

CKSEL1

XIN XOUT

22 21

X1301

12.288MHz

XMCK

CK OUT

LRCK

DATAO

AUDIO

20

IC1501

AUDIO DSP

22

SCK OUT

13

BCK

14

15

16

24

DATA0

D1301

92

LRCK_SW

2

18

GP9

19

HD OUT

6

20

HD IN

IC1503

SELECTOR

SB

AY
1 5

4

5

HCS

HCLK

HACN

2

7PM3

KFSI0

29

BCKI2

28

LRCKI2

17

BCKII

15

LRCKII

30

SDI2

19

LRCK0

69

GP8

68

GP9

35

HD OUT

33

HD IN

34

HCLK

36

HCS

32

HACN

PM

113
56

BST

2

XRST

59

EXLOCK

37

GP12

6

8

BST

XRST

GP12

14

BCKO

20

19LRCKO

18SDI1

SDO1

23

SDO2

24

SDO3

25

MCLK1

9

MCLK2

12

IC1101(2/3)

SYSTEM CONTROLLER

IC1303(2/2)

IC1303(1/2)

35

62

1

45

98 97 95 96 99 100 94 1

DI

CE

DO

CLK

ERROR

ADCC_ANA_OGUE_IN

16

13

14

15

IC1502

SRAM

X1502

13.9MHz

SYSCLK

LRCK

BCK

DOUT

D1113

1

RST

6

10

57

ADCC_DSP_IN

D1112

12

13

14

PCM1608_MC

PCM1608_ML

PCM1608_RST

38

40

41

47

45

46

D1114

37

36

35

34

33

15

PCM1608_MDI

PCM1608_MDO

IC1452

AUDIO CODEC

SCK1

BCK

LRCK

DATA3

DATA1

DATA2

RST

ML

MC

MDI

MDO

VOUT5

VOUT1

VOUT3

VOUT4

10

14

12

11

9

21

22

PCM1800_RST

VOL_DATA_LATCH

VOL_CLK

INL1

DVDD

26

2

INL5

LOUT

49

4

INL4

SLOUT

COUT

SWOUT

IC1131

EEPROM

SDA SCL

5 6

29 30

SDA

40

33

32

SCL

6

INL3

8

INL2

13

ADIFL

16

LIN

19

SLIN

20

CIN

21

SWIN

24

DATA

25

CLK

Q471

+3.3V REG

+7V

L

SL

SL

DISPLAY/
POWER

A

SECTION
(Page 15)

C

SW

888786

STR-K785

: VIDEO

COMPONENT

VIDEO

VIDEO 2

IN

DVD

11

4S22S213

M

J201

J251
(1/2)

Y

P

B/CB

P

R/CR

Y

P

B/CB

IN

P

R/CR

3

CH1 IN2

9

CH2 IN2

14

CH3 IN2

5

CH1 IN3

11

CH2 IN3

12

CH3 IN3

4

SW1 2SW2

IC251

VIDEO AMP

CH1 OUT

CH2 OUT

CH3 OUT

J251
(2/2)

22

20

18

Y

MONITOR

P

B/CB

P

R/CR

CONPONENT

OUT

VIDEO

VIDEO 1

VIDEO 2

(1/2)

VIDEO IN

J203

DVD

VIDEO IN

VIDEO IN

12

1

3

S1

IC203

V3

VIDEO AMP

V1

V2

MON

10

IC807

8

+5V

-5V

+5V REG

IC804

14

-5V REG

J201(2/2)

MONITOR

VIDEO OUT

+ V

- V

1414

4-2. BLOCK DIAGRAM – DISPLAY/POWER SECTION –

POWER AMP

• R-CH is omitted due to same as L-CH.

• Signal Path

FL101

FLUORESCENT

INDICATOR TUBE

F1 F2

14 29

42 31

SEG1-16

GRID1-12

: FM

MAIN
SECTION
(Page 14)

L

SLSL

A

C

SW

8

POWER AMP

8

POWER AMP

8

IC501

+V OUT2

IN2

-V OUT2

IC601

+V OUT2

IN2

-V OUT2

IC701

+V OUT2

IN2

STR-K785

Ver. 1.1

R-CH

RY502

Q608
RELAY
DRIVE

Q509
RELAY
DRIVE

Q508
RELAY
DRIVE

Q708
RELAY
DRIVE

Q560

RELAY
DRIVE

RY601

RY501

RY701

R-CH

RY702

R-CH

TM600(1/2)

L

R

TM602

L

R

TM600(2/2)

J403

12

Q501,502

LIMITER

NF2

9

11

12

Q601,602

LIMITER

NF2

9

11

12

Q701,702

LIMITER

NF2

9

11-V OUT2

Q503

BOOSTER

Q504

BOOSTER

Q603

BOOSTER

Q604

BOOSTER

Q703

BOOSTER

Q704

BOOSTER

Q505,506
CURRENT

DETECT

Q605,606
CURRENT

DETECT

Q705,706
CURRENT

DETECT

Q507

AF POWER

PROTECT

Q607

AF POWER

PROTECT

Q707

AF POWER

PROTECT

D529

D729

AUDIO OUT

J700

PHONES

FRONT

SURROUND

CENTER

SUB WOOFER

SPEAKERS

IMPEDANCE USE 6-16Ω

+3.3V

+2.5V

+5V

IC1901

+3.3V

2

REG

+2.5V

5

REG

IC1031

+5V

3 1

REG

4

D804-807

T901

DIN8CLK9STB

7

IC101

BUFFER

59

60

FL_DATA

82 83

47

FL_CLK

X0

X1101

24MHz

FL_LAT

POWER AMP

IC1001

+5V

3 1

REG

IC1071

+3.3V

3 1

REG

Q860-862

+B
SWITCH

–B

FL101

–20V

RELAY

+B

AUDIO

+7V

AUDIO

–7V

TUNER

+10V

Q851,852

–B

SWITCH

Q801

–20V REG

+B

–B

IC821

+7V

1 3

REG

IC822

–7V

3 2

REG

IC1902

+10V

3 1

REG

IC1904

+3.3V

3 1

REG

D811

R803

D920-923

D910-913

RELAY
DRIVE

Q901

F1

F2

T902

AC
IN

D915D914

RY901

IC100

FL DRIVE

62

66

68

HP RY

SYSTEM CONTROLLER

IC1101(3/3)

X1

A/D0

38

FUNCTION

KEY

S131-139

A/D1

39

FUNCTION

KEY

S100-108

A/D2

40

FUNCTION

KEY

S110-116

FRONT RY

VOL_ENC(B)65VOL_ENC(A)

3 1

ENCODER

RV102

MASTER
VOLUME

REAR RY

64

67

C/SW RY

61

PROTECTOR

POWER KEY

56

S152

46

VACS

?/1

D883

Q881-883

PROTECT

SWITCH

55

HP DETECT

FUSE DETECT

POWER RY

58

SIRCS

AVCC

VCC3

VCC5

RSTX

STOP

IC850(1/2)

+3.3V(STBY)

IC850(2/2)

57

21

63

IC102

REMOTE

54

35

84

23

77

48

1

CONTROL
RECEIVER

IC1111

RESET

1 2

POWER AMP

AUDIO

+5V

AEP

TUNER

3.3V

+B

Q911

AC DET

STR-K785

1515

STR-K785

Ver. 1.2

4-3. PRINTED WIRING BOARD – DIGIT AL BOARD (SIDE A) –

• See page 13 for Circuit Boards Location.

:Uses unleaded solder.

A

B

C

D

E

12

34567

VIDEO

BOARD

CNS250

(Page 30)

M

1

5

R1356

C1361

C1401

R1352

R1362

R1353

C1302

R1303

R1301

C1303

C1304

FB1306

D1302

C1360

R1358

C1357
R1357

C1408

C1405

IC1401

R1318

C1315

R1363

1

C1301

12

R1304

JR1511

R1305

R1359

IC1303

R1402

FB1405

CNS509

48

IC1301

13 24

R1310

R1306

R1360

JR1020

R1307

R1308

R1504

R1401

R1407
R1403

R1316 R1315

37

36

25

C1310

C1309

FB1305

R1309

D1301

X1502

R1502

R1503

R1506

R1505

R1556

IC1452

R1474

37

48

FB1452

C1002

36

1

FB1503

C1494

R1313

R1460

X1301

25

12

R1312
R1311

JR1502

24

13

R1461

C1487

FB1502

C1522 R1515

R1523

R1470

R1484

C1251

C1516

R1555

C1511

C1521

R1471

R1501

30

R1531

1

C1253

R1541

120

31

R1486

R1446

IC1502

R1517

R1552

R1521

R1519

IC1501

R1509

R1475

R1472

C144

R1445

C1566

R1476

91

60

R1436

90

61

R1508

R1547

R1546

R1571

R1572

R1570

R1574

R1573

R1528

R1527

R1543

R1511

IC1503

R1529

R1510

R1154

R1464

C1432

R1435

R1426

AEP

R1544

R1152

C1063

R1545

R1162

R1161

R1155

R1520

R1542

R1539

R1466

R1522

R1540

R1538

R1150

R1121

R1153

R1536

R1534

R1537

R1532

R1144
R1143

R1160

C1913

R1518

R1044

R1149

R1151

R1554

R1526

R1553

R1525

R1136

R1535

R1134

R1533

R1137

C1147

R1168

C1422

R1425

IC1131

R1551

R1135

R1042

R1142

C1148

R1550

R1041

R1140

R1549

R1068

R1067

R1065

R1066

R1120

D1001

R1548

R1115

R1113

R1119

IC1101

R1098

C1495

IC1111

13

X1101

R1127

R1524

R1635

R1082

R1458

FB1308

45

C1107

R1105

R1186

R1122

R1129

R1124

R1094 R1095

R1190 R1128

R1073

R1072

R1071

R1459

R1109

R1123

R1107

R1076

R1088

R1112

R1059

R1108

R1035

R1106

R1083

AUS,SP,SP6

R1077

R1078

AEP

R1058

R1175

R1180

C1123

C1124

R1179

C1122

C1620

R1636

R1097

R1159

R1605

• Semiconductor
Location

Ref. No.

D1001 C-5
D1301 C-3
D1302 C-2

IC1101 D-5
IC1111 D-6
IC1131 E-5
IC1301 C-2
IC1303 D-2
IC1401 E-2
IC1452 E-3
IC1501 D-4
IC1502 C-4
IC1503 E-4

Location

STR-K785

1616