TAURAS TV4K-SM Schematic

TV4K-NICAM / A2 STEREO

COLOUR TELEVISION RECEIVER

SERVICE MANUAL

SECIFICATIONS

z SYSTEM PAL/SECAM,B/G,D/K, I
GERMAN STEREO,NICAM

z POWER INPUT AC 170-260v(50/60Hz)
z POWER CONSUMPTION 100W
z AERIAL IMPEDANCE 75OHM UNVALANCED
z TUNER VOLTAGE SYNTHESIZER TUNING
z RECEICING CHANNELS VHF-L E2-S10

VHF-H E5-S41
UHF E21-E69

z PROGRAMME MAX.99 PROGRAM MEMORIES
z PICTURE TUBE 28”,110°
z SOUND OUTPUT 5W X2
z SPEAKER 8W 8 OHM ×2
z AV JACKS AV SCART ×1

FULL SCART ×1

CAUTION: Before servicing the chassis, read the “Safely Precaution”.

“X -Ray radiation Precaution” and “Product Safety Notice” on Page 2 of

this manual.

X-RAY RADIATION PRECAUTION

1. Excessive high voltage can produce potentially hazardous X-RAY RADIATION. To
Avoid such hazards the high voltage must not be specified limit. The normal value of
the high voltage of this receiver is App. 28.5KV at zero beam current (minimum
brightness) under 230V AC power source. The high voltage must not under any
circumstances exceed 30KV.

2. Each time a receiver requires servicing the high voltage should be checked following
the HIGH VOLTAGE CHECK procedure in this manual. It is recommended the
reading of the high voltage be recorded as a part of the service record. It is
important to use an accurate and reliable high voltage meter.

3. The primary source of X -RAY RADIATION in this TV receiver is the picture tube. For
continued X-RAY RADIATION protection, the replacement tube must be exactly the
same type tube as used in this TV receiver.

4. Some parts in this receiver have special safety-related characteristics for X-RAY
RADIATION protection. For continued safety, parts replacement should be
undertaken only after referring the PRODUCT SAFETY NOTICE below.

SAFETY PRECAUTION

WARNING: Service should not be attempted by anyone unfamiliar with the necessary
Precautions on this receiver.
The following are the necessary precautions to be observed before servicing this
chassis.

1. Since the power supply circuit of this receiver is directly connected to the AC

power line. An isolation transformer should be used during any dynamic service to
avoid possible shock hazard.

2. Always discharge the picture tube anode to the CRT conductive coating before

handling the picture tube. The picture tube is highly evacuated and if broken, glass
fragments will be violently expelled. Use shatterproof goggles and keep picture tube
away from the unprotected body while handling.

3. When replacing a chassis in the cabinet, always be certain that all the protective

devices are put back in place, such as: nonmetallic control; knobs, insulating covers,
shields, isolation resistor-capacitor, network, etc.

4. When replacing parts or circuit boards, disconnect the power cord.

5. When replacing a high voltage resistor (metal oxide resistor) on circuit hoard,

keep the resistor 10mm(1/2 in.) away from circuit board.

6. Connection wires must be kept away from components with high voltage or high

temperature.

7. If any fuse in this TV receiver is blown, replace it with the FUSE specified in the

chassis parts list.

8. The receiver is designed to operate with 230V(50Hz) AC mains.

PRODUCT SAFERY NOTICE

Many electrical and mechanical parts in this chassis have special safety-related
characteristics are often passed unnoticed by a visual inspection and the X-RAY
RADIATON protection afforded by them cannot necessarily be obtained by using
replacement components rated for higher voltage. The use of substitute replacement
parts that do not have the same safety characteristics as specified in the parts list may
create shock, fire, X-RAY RADIATION or other hazards.

GENERAL ADJUSTMENT

AUTOMATIC DEGAUSSING

An automatic degaussing coil is attached around the picture tube, degaussing the tube
properly in about one second after the set is switched on. If the receiver is moved or
faced on a different direction, the power must be switched off at least 15 minutes in
order that the automatic degaussing circuit operated properly. External is necessary if
the automatic degassing proves ineffective when the set is moved.

B+ ADJUSTMENT

CAUTION: To avoid X-ray hazards, B+ voltage must be set in the scale of 140V+/-

0.5V.

1. Make sure the AC power supply is 230V, 50Hz.

2. Switch on the TV receiver, tune in an active channel.

3. Measure the voltage between C641 on Main P.C. Board DC voltmeter.

4. Set contrast, brightness, color to maximum.

5. Adjust VR631 on Main P. C. Board for B+140V+/-0.5V voltage reading.

HIGH VOLTAGE CHECK

CAUTION: There is no high voltage adjustment in this chassis, B+140V voltage

directly relates to the high voltage. The high voltage does not exceed 30KV under any
conditions.

1. Connect an accurate high voltage meter to the second cap of the picture tube.

2. Turn on the receiver, set brightness and contrast to minimum (Zero beam current).

3. Make sure the high voltage does not exceed 30KV.

4. NO matter whether the luminance, contrast and chrominance controls are set to

maximum or minimum, the high voltage must be kept under 30KV.

FOCUSING

Receive a TV test pattern signal; adjust controls for optimum picture. Adjust Focus
Control for a well-defined, sharpest display in the center area of the screen.

ADJUSTMENT AND SERVICING THE VHASSIS

SERVICE MODE

To enter the service mode, a special remote control which contains an additional
SERVICE key must be used to setup the chassis in producing. See the illustration.
Press the ‘SERVICE’ key on remote control, TV will display service menu as following
table 1. To select the parameter requiring adjustment, use the ‘P+/P-’ keys. To adjust
the selected parameter, use the ‘V+/V-’ keys. To quit the service mode, press the ‘P.P.’
key on remote control when in the service mode.

Table 1

Parameter Value
Red Gain 45 Fix value
DC Red 063
Green Gain 45
DC Green 063
Blue Gain 45
DC Blue 063
Apr Threshold 15
Logo 6------------

To enter the table 2, press the ‘OK’ key for the first time on the remote control while in
above service mode.

Fix value
Fix value
Fix value
Fix value
Fix value
Fix value
Fix value