RM-781
SERVICE MANUAL
US Model
Chassis No.
Canadian Model
Chassis No.
P-3B CHASSIS
Television
system
Channel
coverage
Picture
tube
Power
requirements
Power
consumption
Accessories
supplied
Optional
accessories
Speaker size :
American TV standards
VHF : 2-13
UHF : 14-69
MODELS OF THE SAME SERIES
SPECIFICATIONS
Speaker
Impedance
Speaker Wattage
Dimensions
Weight
Approx. 2W
Approx. 356X 331 X 407 mm (w/h/d)
Approx.
Cable TV : 1-125
Mirror
black
Trinitron
tube
13-inch
picture
measured
diagonally
picture tube measured diagonally
VIDEO IN (phono jack) :
75ohms
unbalanced,
sync
negative
AUDIO IN(phono jack) : 408mVrms
(100%
modulation)
impedance : 47k ohms
120V AC,
97W
(Max.)
3W (STAND BY)
Remote Commander RM-781
.
with 2 size AA (R6) batteries
VHF/UHF telescopic dipole antenna (1)
Antenna connector (1)
U/V mixer EAC-66
Connecting
cord
etc.
77mm
X 1
Designs and specifications are subject to change without
notice.
COLORTV
TABLE OF CONTENTS
Section
1.
GENERAL
1-1.
.......................................
.
l-2.
....................
...........
1-3.
l-4.
1-5.
Enjoying the Convenient Features
l-6.
...................................................
.
2.
DISASSEMBLY
2-l.
..............................................
2-2.
....................................
3.
SET-UP
ADJUSTMENTS
3-l.
Beam
Landing.................................................
3-2.
..................................................
3-3.
..............................................................
3-4.
.........................................................
3-5.
.................................................
14
WARNING
!!
ATTENTION!!
AN
ISOLATION
TRANSFORMER
SHOULD
BE
USED
DURING
ANY
SERVICE
TO
AVOID
POSSIBLE
SHOCK
HAZARD,
BECAUSE
OF
LIVE
CHASSIS.
THE
CHASSIS
OF
THIS
RECEIVER
IS
DIRECTLY
CON-
NECTED TO THE AC POWER LINE.
D'EVITER
TOUT
RISQUE
D'ELECTROCUTION
PROVENANT D'UN
TENSION,
UN
TRANSFORMATEUR
D'ISOLEMENT
ETRE
LORS DE TOUT
LE
DE CE
EST
L'ALIMENTATION
SECTEUR.
SAFETY-RELATED
COMPONENT
WARNING
!!
COMPONENTS IDENTIFIED BY SHADING AND MARK
ON
THE
SCHEMATIC
DIAGRAMS,
EXPLODED
VIEWS 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.
CIRCUIT
ADJUSTMENTS
THAT
ARE
CRITICAL
TO
SAFE
OPERATION
IDENTIFIED
IN
THIS
MANUAL.
FOLLOW THESE PRO-
CEDURES
WHENEVER
CRITICAL
COMPONENTS
ARE
REPLACED
OR
IMPROPER
OPERATION
IS
SUSPECTED.
Section
4. SAFETY RELATED
15
5.
ELECTRICAL
ADJUSTMENTS
5-1.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6. DIAGRAMS
6-1.
.................................
6-2.
Printed Wiring Board .....................................
6-3.
..........................................
6-4.
..............................................
27
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.
.
.
.
.
..a............................
ATTENTION
AUX
COMPOSANTS
LA
LES COMPOSANTS
PAR UNE TRAME ET
PAR UNE
LES
DE
LES
VUES
ET LES
DE
PIECES
SONT
IMPORTANCE CRITIQUE POUR LA
DU FONCTIONNEMENT. NE LES
PLACER
QUE
PAR
DES
COMPOSANTS
SONY
DONT
LE
DE
EST
DANS LE
MANUEL
OU
DANS
DES
PAR
SONY.
LES
DE
`*CIRCUIT
DONT
TANCE
EST
CRITIQUE
POUR
LA
DU
FONCTIONNEMENT
SONT
IDENTIFIES
DANS
LE
MANUEL.
CES
LORS
DE
CHAOUE
REMPLACEMENT
DE
COMPOSANTS
CRITIQUES.
OU
LORSQU'UN
MENT EST
SAFETY
CHECK-OUT
(US Model only)
After correcting the original service problem,
perform the following safety checks before releasing
the set to the customer:
1.
Check the area of your repair for unsoldered or
poorly-soldered connections. Check the entire
board surface for solder splashes and bridges.
2.
Check the
wiring to ensure that no
wires are "pinched" or contact high-wattage
resistors.
3.
Check that all control knobs, shields, covers,
ground straps, and mounting hardware have
been replaced. Be absolutely certain that you
have replaced all the insulators.
4.
Look for unauthorized replacement parts, par-
ticularly transistors, that were installed during a
previous repair. Point them out to the customer
and recommend their replacement.
5.
Look for parts which, though functioning, show
obvious signs of deterioration. Point them out
to the customer and recommend their replace-
ment ,
6.
Check the line cord for cracks and abrasion.
Recommend the replacement of any such line
cord to the customer.
7.
Check the condition of the
antenna
(if any).
Make sure the end is not broken off, and has
the plastic cap on it. Point out the danger of
impalement on a broken antenna to the
customer,
and' recommend the antenna's
replacement.
8.
Check the B+ and HV to see they are at the
values specified. Make sure your instruments
are accurate; be suspicious of your HV meter
if sets always have low HV.
9.
Check the antenna terminals,
trim,
knobs, screws, and all other
exposed metal parts for AC leakage.
Check
leakage as described below.
LEAKAGE
TEST
The AC leakage from any exposed metal part to
earth ground and from all exposed metal parts to any
exposed metal part having a return to chassis, must
not exceed 0.5
(500
Leakage
current can be measured by any one of three
methods.
1.
A
commercial leakage tester, such as the
Simpson 229 or RCA
Follow the
manufacturers' instructions to use these instru-
ments.
2.
A battery-operated AC milliammeter. The Data
Precision 245 digital multimeter is suitable for
this job.
3.
Measuring the voltage drop across a resistor by
means of a VOM or battery-operated AC volt-
meter.
"limit" indication is
so
analog meters must have an accurate
voltage scale.
The Simpson 250 and Sanwa
SH-63Trd are examples of a passive VOM that
is suitable. Nearly all battery operated digital
multimeters that have a 2V AC range are
suitable. (See Fig. A)
HOW TO FIND A GOOD EARTH GROUND
A cold-water pipe is guaranteed earth ground; the
cover-plate retaining screw on most AC outlet boxes is
also at earth ground. If the retaining screw is to be
used as your earth-ground, verify that it is at ground
by measuring the resistance between it and a
water pipe with an ohmmeter. The reading should be
zero ohms.
If a cold-water pipe is not accessible,
connect a 60-100
trouble light (not a neon
lamp) between the hot side of the receptacle and the
retaining screw. Try both slots, if necessary, to locate
hot side of the line, the lamp should light at
normal brilliance if the screw is at ground potential.
(See Fig.
To Exposed Me tat
Parts on Set
AC
voltmeter
10.75 VI
Earth
Ground
A.
Using an AC voltmeter to check AC leakage.
Fig.
Checking for earth ground.
Trouble Light
Cold-water Pipe
SECTION
GENERAL
l-l. LOCATION OF CONTROLS
to the
for
b
I
control
detector
VOLUME
buttons
CHANNEL
buttons
switch
On-screen
Channel
numbers
.
"SLEEP"
. `VIDEO
`AUTO PROGRAM', `TIMER or TIMER
BLOCK
Bar
for volume
.
for
AUDIO IN jack
VIDEO IN jack
VHF/UHF
antenna
terminal
MUTING
button
TIMER/BLOCK
setting
buttons
(TIMER/BLOCK,
CLEAR,
OFF/REPEAT)
Channel
presetting
buttons
(AUTO
PGM,
ADD,
ERASE)
Channel
number
buttons
DISPLAY
button
PICTURE
buttons
VOL (volume)
buttons
-SLEEP
POWER
switch
Picture
adjusting
buttons
(SELECT,
RESET,
LEVEL
CABLE
button
TV/VIDEO
button
ENTER
button
JUMP
button
CH (channel) +/-buttons
-The
of these buttons
are also
on
TV.
. In normal
last up to half a
the Commander does not operate properly, the
be exhausted Replace them
new ones.
l
To
damage from
battery leakage, remove
the
when the Commander
not be used for a
l
If a Remote Commander that
not recommended
used
to operate
or the
Remote Commander
used to operate another
the TV may not operate
properly
l-2. PRESETTING TV CHANNELS
1
Press POWER on the TV or the Remote
Commander to turn the
N on.
To preset VHF or UHF
To preset cable TV
channels
channels
3 Press AUTO PGM.
"AUTO PROGRAM
on the screen and
channels (other than the channels already preset)
be preset I"
sequence The channels
preset reman I" the
memory
When no more channels can be found the
stops
the lowest numbered channel
channels of
TV are:
I
T O check Preset channels
CH
UHF
I
1
the "VIDEO"
the screen
To add the channels that
not
preset
because
strength was
weak
erase unnecessary channels, follow the steps
To preset only
Press the
on the TV or the Remote
Commander so that a channel "umber appears
the
on the next Page
-ENTER
1
Press the channel number button(s) and then ENTER to select
the channel to be added or erased.
2 Toaddchannels PressA
ADD
a
A
appears
a moment
channel has now bee" added to the channel scan memory
To erase channels
Press ERASE.
ERASE
A
appears for a moment
channel has now bee" erased from the channel scan memory
The next
the CH
button
pressed
channel
be
Repeat steps 1 and 2 for other channels to be added or erased
channel chart'
Cable
systems
letters or numbers
channels
To
a channel refer
the
below
Number on
TV
15
17
22
23
24
25
26
27
28
29
30
CAT" channel A 8 A-7 A-6 A
39 ................
$3
97
98
123 124 125
Check
your local cable
company for more complete
. The
the cable
channels
the
channels