Panasonic TX-21S1T User manual

Panasoni
Service Manual
Colour Television
Z—5 Chassis
TX-—21S1T /TC-—21S1R
TX—14S1T /TC—14S1R
Power Source : 220 / 240 V AC 50Hz.
58W TX—21S1T / TC—21S1R
39W TX-1451T / TC—14S1R
Power Consumption :
Aerial impedance : 75Q unbalanced, Coaxial Type
Receiving System : PAL — | (UHF)
PAL — 60
Receiving Channels : UHF E21 — E69
Intermediate Frequency : Video 39.5 MHz
Sound 33.5 MHz
Colour 35.07 MHz PAL
Video/Audio Terminals
AV1 IN Video (21 pin) 1Vp—p 75Q
Audio (21 pin) 500mVrms 10kQ
RGB (21 pin)
AV1 OUT Video (21 pin) 1 Vp—p 75Q
Audio (21 pin) 500 mV rms1kQ
RCA IN Video 1 Vp—p 752
RCA IN Audio 500 mVrms, 10KQ
ORDER NO. SM-—94001
A51EAL55X13
51 cm V 90°
measured diagonally
A34EAC01X13 \
36 cm V 90°
measured diagonally.
Picture Tube :
Audio Output : 5 Watt
8Q, Rectangular
Remote Control
2 x R6(UMS3) Batteries
High Voltage :(zero beam current)
21S1 Series 14S1 Series
26.4Kv 21.5Kv
21S1 Series 1481 Series
Speaker
Accessories supplied :
Dimensions : Height: 477mm 364mm
Width: 518mm 389mm
Depth: 478mm 384mm
21S1 Series 14S1 Series
Net Weight 21Kg 10Kg
Specifications are subject to change without notice.
Weight and dimensions shown are approximate.
IMPORTANT
This receiver uses a HOT chassis, after service please ensure that the chassis is returned to its correct position.
Particular care being taken to the position of the customer controls.
Failure to do so could endanger customer safety.
Panasonic (U.K.) LTD.
WILLOUGHBY ROAD,
BRACKNELL,
BERKS,
RG12 8FT.

BX—21511/1C-21351R
VELSMeSs on
Contents
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Schematic DiagraMs ......... 0... eee cece eee eee eee eee
Exploded VIOWS ......-.. cc cece cee e cece e een e eee e eee e eens
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Safety Precautions
General Guide Lines
1. It is advisable to insert an isolation transformer in the AC
supply before servicing a hot chassis.
2. When servicing, observe the original lead dress in the high
voltage circuits. If a short circuit is found, replace all parts
which have been overheated or damaged by the short
circuit.
3. After servicing, see that all the protective devices such as
insulation barriers, insulation papers, shields and isolation
R—C combinations are correctly installed.
4. When the receiver is not being used for a long period of
time, unplug the power cord from the AC outlet.
5. Potentials as high as 26.4Kv kV are present when this
receiver is in operation. Operation of the receiver without
the rear cover involves the danger of a shock hazard from
the receiver power supply. Servicing should not be
attempted by anyone who is not familiar with the
precautions necessary when working .on high voltage
equipment. Always discharge the anode of the picture to
the chassis before handling the tube.
6. After servicing make the following leakage current checks
to prevent the customer from being exposed to shock
hazards.
Leakage Current Cold Check
1. Unplug the AC cord andconnect ajumper between thetwo
prongs of the plug.
Turn on the receiver's power switch.
Measure the resistance value with an ohmmeter, between
the jumpered AC plug and each exposed metallic cabinet
part on the receiver, such as screw heads, aerials ,
connectors, control shafts etc. When the exposed metallic
part has a return path to the chassis the reading should be
between 4M Q and 20M Q. When the exposed metal does
not have a return path to the chassis the reading must be
infinite.
Leakage Current Hot Check
1. Plug the AC cord directly into the AC outlet. Do not use an
isolation transformer for this check.
2. Connect a 2k ohm 10W resistor in series with an exposed
metallic part on the receiver and an earth such as a water
pipe.
3. Use an AC voltmeter with high impedance to measure the
potential across the resistor.
4. Check each exposed Metallic partand check the voltage at
each point.
5. Reverse the AC plug at the outlet and repeat each of the
above measurements.
6. The potential at any point should not exceed 1.4 Vrms. In
case ameasurementis outside the limits specified, there is
a possibility of a shock hazard, and the receiver should be
repaired and rechecked before it is returned to the
customer.
HOT CHECK CIRCUIT
A.C. Voltmeter
Water Pipe
To
Instrument’s
|
(Earth)
exposed
metallic parts 2K ohm 10W
Fig.1
X—Radiation Warning
1. The potential sources of X—Radiation in TV sets are the
high voltage section and the picture tube.
2. Whenusingapicture tube testjig for service ensure thatthe
jig is capable of handling 28.0 kV(21S1 Series) and 23kV
(14S1 Series) without causing X— Radiation.
NOTE : itis important to use an accurate periodically calibrated
high voltage meter 2
1. Set the brightness to minimum.
2. Measure the high voltage. The meter should indicate:—
26.4Kv + 1.5 kV (2181 Series)
21.5Kv + 1.5 kV (1481 Series)
ifthe meterindicationis out oftolerance, immediate service
and correction is required to prevent the possibility of
premature component failure.
3. To prevent an X—Radiation possibility, itis essential to use
the specified tube.

TX-21811/1C-2151F
BP SLSSALSESSI:
SHUT DOWN CIRCUIT TEST
This test must be made as a final check before the set is returned to the customer.
1.
2.
Receive the Phillips pattern.
Check that the shut-down circuit functions when —60V is applied to TPE40, but does not function when —40V is applied.
Location Of Controls
RED CUTOFF R364
GREEN DRIVE R357
GREEN CUTOFF R362
RED DRIVE R358
BLUE CUTOFF R369
H.WIDTH L552
SUB
GLR
R607
TEXT
CONTRAST
H.
CENT
R502
R3515
R.FAGC
R109
V.
CENTRE
$451
SERVICE SWITCH
$301
SUB CONT SUB BRT V. HEIGHT R465
Fig. 2 R316 (R306)
How to move the chassis into the Service position
1.
2.
Hold and lift the rear of the E— PCB chassis and gently pull the chassis toward you.
Release the respective wiring clips and rotate the chassis clockwise.
For the 21” model,
a)
Place
the
lower
edge
of
the
chassis
against
the
’L’
shaped
stopper
located
in
the
chassis
rail
whilst
sliding
the
upper
edge
of
the
board
into
the
chassis
holding
rib.
OR
b) Slidethe lower edge ofthe chassis into the power cable holder case whilstslidingthe upperedge ofthe board into the chassis
holding rib.
For the 14” model
a)
Slidethe
lower
edge
ofthe
chassis
into
the
power
cable
holder
case
whilstsliding
the
upperedge
ofthe
board
intothe
chassis
holding
rib.
After servicing ensure all wiring is returned to its original position before returning the receiver to the customer.
21S1 SERIES 14S1 SERIES
Chassis
Chassis
Holding
Rib
E PC.B. Power cable
Rail holder case

iX=2151 1/1 C-2151R_ |
CGC CS
ADJUSTMENTS
ITEM/PREPARATION ADJUSTMENT PROCEDURE
BVOEIACE 1. Confirm the indicated test points for the specified voltage.
1. Operate the TV set.
2. Set controls : 21S1 Series 14S1 Series
Bright (R318) minimum
minimum TPE 13:1245V + 1.5V 103V. + 1.5V
Beam Current
TPE 11: 31V + 2Vv 27.0V + 2V
TPE 1: WW + 1V 11V ct 1V
TPE6: 28.0V 4+ £1.5V 26.7V + 1.5V
TPE9: 23.0V + 1.0V 23.3V + 1.0V
TPE 4: 163V 4 = 1.0V 16.0V + 1.0V
TPE5: 12.0V + 1.0V 12.0V + 1.0V
TPE 3: 8.0V + 1.0V 8.0V + 1.0V
TPE 2: 5.0V + 0.3V 5.0V cz (0.8V
TPE14: 30V + 2.5V 30V + 2.5V
1. Apply 39.5 Mhz continuous wave to TPE54 (IF pin of Tuner)
AFC (0.5Vp—p/75Q)
2. Adjust L104 so that voltage at TPE27 becomes 2.5+0.1V.
1. Operate the TV set. 3. Change the frequency and confirm the voltage as shown
below.
2. Connect a DVM to TPES8. + 100kHz: Less than 1.0V
— 100kHz: more than 4.0V
1. Turn RF AGC conirol R109 fully counterclockwise.
RF
AGC
2.
Slowly
turn
RF
AGC
control
clockwise
to
set
it
at
the
point
just
before
voltage at
TPE28
starts
to
fall.
1. Receive the Philips pattern.
2. Set the input level to 60 + 2 dB (75Q open).
3. Connect an oscilloscope to TPE59 (RF AGC terminal).
1. Connect a high voltage meter (Electrostatic type) to an anode
of the picture tube.
2. Confirm that the high voltage is within a range of
1. Receive a crosshatch pattern. 21S1 Series 14S1 Series
HIGH VOLTAGE
2. Set Contrast, Bright and Sub—Bright controls to their 26.4Kv+1.5kV 21.5Kv + 1.5kV.
minimum positions (Zero beam current).

| -TX-2151 1/1 C-21S 7h
LT X—14517/1 C-14515
ADJUSTMENTS
SUB NTRAST
:
i
Adjust
Sub
brightness
(R306)
to
set
Adjust
R316
1.
Receive
a
Philips
pattern.
fhe
Blaciclevel
16
ON.
2.8V+/-0.1V—p
(Input level 75dB). .
Adjust the Sub contrast (R316) to set
Connect an oscilloscope to the drive voltage to 2.8V+/— 0.1V—p.
TPY1.
Set controls to :
Brightness minimum
Contrast maximum
Colour
minimum
~~
Adjust
(R306)
4
Sharpness centre
Pix minimum Fig.5
SUB COLOUR 1.6Vp—p +/— 0.1V
Connect a short jumper between
TPE6 and earth.
Adjust the sub colour (R607) for
1. Receive a PAL colour bar pattern.
2. Set controls to:
Brightness minimum 1.6Vp—p +/— 0.1V at TPE15 as
shown in Fig.6.
Contrast maximum
Sub colour eanire Remove the earth jumper wire.
Colour centre
Sharpness minimum
. Connect an oscilloscope to TPE15.
TEXT CONTRAST
1. Receive a teletext signal. 1. Adjust R3515 to check the maximum
level > 1.5v and a minimum level < 0.6v.
2. Connect an oscilloscope T2 pin 5. 2. . Adjust R3515 to centre. (pk — pk *)

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