BEKO 142 SERVICE MANUAL.pdf

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CONTENTS
PAGE
Safety Instructions
3
Technical Specifications
4
Pin Voltages of IC’s
5
Pin Voltages of Some Transistors
8
Oscillograms
9
Electrical and Service Adjustments
12
Trouble Shooting Guide
16
Parts List
23
Circuit Diagram PIP Module
30
Circuit Diagrams
Attached
27/05/2002, Version 2
SAFETY INSTRUCTIONS
GENERAL GUIDELINES
1. It is advised to insert an isolation transformer
in the AC supply before servicing a hot
chassis.
2. Potentials as high as 33KV 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 any one who is not
competent with the precautions necessary
when working on the high voltage
equipment. Always discharge the anode of
the tube.
3. When servicing observe the original lead
dress in the high voltage circuits. If a short
circuit is found, replace all the parts which
have been overheated or damaged by the
short circuit.
4. Always use the manufacturer’s replacement
safety components. The critical safety
components
marked with
on the
schematics diagrams should not be
replaced by other substitutes. Other
substitute may create the electrical shock,
fire or other hazards. Take attention to
replace the spacers with the originals.
Furthermore where a short circuit has
occurred, replace those components that
indicate evidence of overheating.
5. After servicing, see that all the protective
devices such as insulation barriers, insulation
papers,
shields
and
isolation
R-C
combinations are correctly installed.
6. When the receiver is not being used for a
long time of period of time, unplug the
power cord from the AC outlet.
7. After servicing make the following leakage
current checks to prevent the customer
from being exposed to shock hazard.
LEAKAGE CURRENT COLD CHECK
1. Unplug the AC cord and connect a jumper
between the two prongs of the plug.
2. Turn the receiver’s power switch on.
3. 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 a return path to the
chassis the reading should be between
4Mohm and the 20Mohm. 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 in to the AC
outlet. Do not use an isolation transformer
for this check.
2. Connect a 2Kohm 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 part and
check the voltage at the each point.
5. Reverse the AC plug at the outlet and
repeat each of the above measurements.
6. The potential at the any point should not
exceed 1.4 Vrms. In case a measurement is
outside the limits specified, there is the
possibility of a shock hazard, and the
receiver should be repaired and rechecked
before it is returned to the customer.
HOT CHECK CIRCUIT
AC-Voltmeter
TO INSTRUMENTS
EXPOSED
METALLIC PARTS
Water pipe
(earth)
2 K Ohm
Figure 1
X-RAY RADIATION WARNING
The primary source of X-ray radiation in this receiver
is the picture tube. The chassis is specially
constructed to limit X-ray radiation. For continued
X-ray radiation protection, replace the tube with
the same type of the original one.
CAUTION
AFTER REMOVAL OF THE ANODE CAP, DISCHARGE
THE ANODE OF THE PICTURE TUBE AND THE ANODE
CAP TO THE METAL CHASSIS, CRT SHIELD, OR THE
CARBON PAINTED ON THE CRT WITH A HIGH
VOLTAGE PROBE AND MULTIMETER (SELECT VDC)
AND THEN SHORT CIRCUIT DIRECTLY TO DISCHARGE
COMPLETELY.
TECHNICAL SPECIFICATIONS
Power source:
Power consumption (max.)
1
:
220-240 VAC, 50-60Hz
120 W
125 W
145 W
140 W
150 W
155 W
165 W
160 W
3W
75Ohm, coaxial type
PAL BG
PAL SECAM BG
PAL SECAM BG DK
PAL SECAM BG LL’
PAL I
VHF BAND I ,
VHF BAND III ,
CABLE TV
UHF BAND
3.58&4.43 MHz
Stereo :
Mono :
High Voltage
:
2 x 10W RMS at %10 THD (Except 21” Pure Flat)
2 x 7W RMS at %10 THD (21” Pure Flat)
+ 20W RMS at %10 THD (if subwoofer available)
2 x 7W RMS at %10 THD
25”, 28”4/3
28”16/9, 29”, 32” Super Flat
32” Pure Flat, 33”
CH2-4
CH5-12
S1-41
CH21-69
21” Pure Flat
25”, 28” Mono
25”, 28” 4/3, 29” Pure Flat
29” Super Flat
28” 16/9 Super Flat
28” 16/9 Pure Flat, 32” Super Flat
32” Pure Flat
33”
Standby power consumption :
Aerial impedance
:
Receiving system
2
:
Receiving channels:
NTSC Playback Frequencies:
Audio outputs
:
28.5 ± 0.5 KV
29.0 ± 0.5 KV
29.5 ± 0.5 KV
%25.6 ± %38 of EHT
0-1400 V
6.2 ± 0.2 Vrms
AV1/2 IN
AV1 IN
AV1/2 OUT
AV2 IN (RCA)
Focus voltage
:
Grid 2 voltage
:
Heater voltage
:
Video/Audio Terminals :
Video : 1 Vpp,75 Ohm
Audio : 0.5 Vrms, >10 Kohm
RGB
Video : 1 Vpp, 75 Ohm
Audio : 0.5 Vrms, <1 Kohm
Video : 1 Vpp, 75 Ohm
Audio : 0.5 Vrms, >10 Kohm
Operating temperature
:
Safety
X-Ray radiation
1
2
0-45 Degrees
IEC 65 /BS P2N
ACC. IEC 65/BS P2N
:
:
: 20W should be added to find the max. power consumption of the models with subwoofer.
: TV set is produced to receive “one” of these colour and sound systems.
12

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