ADMIRAL TG-2900A Service Manual
29 "N"Chassis
CONTENTS
1. PRECAUTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Safety Precaution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Servicing Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Precautions for Electrostatically Sensitive Devices . . . . . 6
2. SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. DESCRIPTION OF CONTROLS . . . . . . . . . . . . . . . . . . . . . . 8
4. ALIGNMENT AND ADJUSTMENTS . . . . . . . . . . . . . . . . . . . 9
Preadjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Factory / Service Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Other Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5. USING DEVICES AND DESCRIPTION . . . . . . . . . . . . . . . . 16
Main IC (TV Processor/u-com/ TMPA8857) . . . . . . . . . . . 16
15W+15W Dual Bridge Amplifier (TDA7297) . . . . . . . . . . 17
MSP 3420G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Power (KA5Q1265RF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Vertical deflection output circuit(LA78045) . . . . . . . 23
Triple video output amplifier(TDA6108JF) . . . . . . . 24
6. TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
No Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
In stand-by status (POWER OK), TV is switched on,
SMPS turns off and LED turns off (ON/OFF)
. . . . . . . . . . . 26
No Picture (sound ok) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
No Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Vertical Line(Reference Line) . . . . . . . . . . . . . . . . . . . . . . 29
7. BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8. PCB LAYOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9. PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
10. CRICUIT DIAGRAM
1. Precautions
Follow these safety, servicing and ESD precautions to prevent
damage and protect against potential
hazards, such as electrical shock and X-rays.
1-1 Safety Precautions
1. Be sure that all of the built-in protective devices are replaced.
Restore any missing protective shields.
2. When reinstalling the chassis and its assemblies, be sure to restore all protective devices,
including : nonmetallic control knobs and compartment covers.
3. Make sure that there no cabinet openings through which people-particularly childrenmight
insert fingers and contact dangerous voltages. Such opening include the spacing between
the picture tube and the cabinet mask, excessively wide cabinet ventilation slots, and improperly fitted back covers.
If the measured resistance is less than 1.0 megohm or greater than 5.2 megohms, an
abnormality exists that must be corrected before the unit is returned to the customer.
4. Leakage Current Hot Check (Figure 1-1) :
Warning : Do not use an isolation transformer during this test. Use a leakage current
tester or a metering system that complies with International Electrotechnical Commission
65.(IEC 65)
FIGURE 1-1
AC LEAKAGE TEST
ALSO TEST WITH
PLUG REVERSED
READING SHOULD NOT
BE ABOVE
0.7mA PEAK AC2mA DC.
EARTH
GROUND
LEAKAGE
CURRENT
TEATER
POWER
CORD
CEVICE
UNDER
TEST
TEST ALL
EXPOSED METAL
SURFACES
5. With the unit completely reassembled, plug the AC line cord directly the power outlet.
With the unit' s AC switch first in the ON position and then OFF, measure the current
between a known earth ground (metal water pipe, conduit, etc) and all exposed metal
parts, including: antennas, handle brackets, metal cabinets, screwheads and control
shafts. The current measured should not exceed 0.5 milliamp. Reverse the power-plug
prongs in the AC outlet and repeat the test.
6. Antenna Cold Check:
With the unit's AC plug disconnected from the AC source, connect an electrical jumper
across the two AC prongs. Connect one lead of the ohmmeter to an AC prong. Connect
the other lead to the coaxial connector.
7. X-ray Limits:
The picture tube is especially designed to prohibit X-ray emissions.
To ensure continued X-ray protection, replace the picture tube only with one that is the
same type as the original. Carefully reinstall the picture tube shields and mounting
hardware: these also provide X-ray protection.
8. High Voltage Limits:
High voltage must be measured each time servicing is done on the +B, horizontal
deflection or high voltage circuits.
9. High voltage is maintained within specified limits by close-tolerance, safety-related
components and adjustments. If the high voltage exceeds the specified limits, check
each of the special components.
10. Design Alteration Warning:
Never alter or add to the mechanical or electrical design of this unit.
Example: Do not add auxiliary audio or video connectors. Such alterations might
create a safety hazard. Also, any design changes or additions will void the
manufacturer' s warranty.
11. Components, parts and wiring that appear to have overheated or that are otherwise
damaged should be replaced with parts that meet the original spec ifications. Always
determine the cause of damage or overheating, and correct any potential hazards.
12. Observe the original lead dress, especially near the following areas:
Antenna wiring, sharp edges, and especially the AC and high voltage power supplies.
Always inspect for pinched, out-of place, or frayed wiring.
Do not change the spacing between components and the printed circuit board. Check
the AC power cord for damage. Make sure that leads and components do not touch
thermally hot parts.
13. Picture Tube Implosion Warning:
The picture tube in this receiver employs "integral implosion" protection.
To ensure continued implosion protection, make sure that the replacement picture tube
is the same as the original.
14. Do not remove, install or handle the picture tube without first putting on shatterproof
goggles equipped with side shields.
Never handle the picture tube by its neck. Some "in-line" picture tubes are equipped
with permanetly attached diflection yoke: do not try to remove such "permanently
attached" yokes from the picture tube.
15. Product Safety Notice:
Some electrical and mechanical parts have special safety-related characteristics which
might not be obvious from visual inspection.
These safety features and the protection they give might be lost if the replacement
component differs from the original--even if the replacement is rated for higher voltage,
wattage, etc.
Components that are critical for safety are indicated in the circuit diagram by
shading( )
Use replacement components that have the same ratings, especially for flame
resistance and dielectric strength specifications. A replacement part that does not have
the same safety characteristics as the original might create shock, fire or other hazards.
1-2 Servicing Precautions
Warning 1: First read the "Safety Precaution" section of the manual.
If some unforeseen circumstance creates a conflict between the servicing and safety
precautions, always follow the safety precaution.
Warning 2: An electrolytic capacitor installed with the wrong polarity might explode.
1. Servicing Precautions are printed on the cabinet. Follow them.
2. Always unplug the unit' s AC power cord from the AC power source before attempting
to: (a) Remove or reinstall any component or assembly, (b) Disconnect an electrical
plug or connector, (c) Connect a test component in parallel with an electrolytic capacitor.
3. Some components are raised above the printed circuit board for safety.
An insulation tube or tape is sometimes used. The internal wiring is sometimes clamped
to prevent contact with thermally hot components.
Reinstall all such elements to their original position.
4. After servicing, always check that the screws, components and wiring have been
correctly reinstalled. Make sure that the portion around the serviced part has not been
damaged.
5. Check the insulation between the blades of the AC plug and accessible conductive parts
(examples: metal panels,. input terminals).
6. Insulation Checking Procedure: Disconnent the power cord from the AC source and
turn the power switch ON. Connect an insulation resistance meter (500V) to the blades of
the AC plug.
The insulation resistance between each blade of the AC plug and accessible conductive
parts (see above) should be greater than 1 megohm.
7. Never defeat any of the B+ voltage interlocks. Do not apply AC power to the unit (or any
of its assemblies) unless all solid-state heat sinks are correctly installed.
8. Always connect a test instrument' s ground lead to the instrument chassis ground before
connecting the positive lead: always remove the instrument' s ground lead list.
!
1-3 Precautions for Electrostatically Sensitive Devices (ESDs)
1. Some semiconductor ("solid state") devices are easily damaged by static electricity.
Such some components are called Electrostatically Sensitive devices (ESDs); examples
include integrated circuits and some field-effect tran sistors. The following techniques will
reduce the occurrence of component damage caused by static electricity.
2. Immediately before handling any semiconductor components or assemblies, drain the
electrostatic charge from your body by, touching a known earth ground. Alternatively,
wear the discharging wrist-strap device. (Be sure to remove it prior to applying powerthis is an electric shock precaution.
3. After removing an ESD-equipped assembly, place it on a conductive surface such as
aluminum foil to prevent accumulation of electrostatic charge.
4. Do not use freon-propelled chemicals. These can generate electrical charges that
damage ESDS.
5. Use only a grounded-tip soldering iron when soldering or unsoldering ESDS.
6. Use only an anti-static solder removal device. Many solder removal devices are not rated
as "anti-static"; these can accumulate sufficient electrical charge to damage ESDS.
7. Do not remove a replacement ESD front its protective package until you are ready to
install it. Most replacement ESDs are packaged with leads that are electrically shorted
together by conductive foam, aluminum foil or other conductive materials.
8. Immediately before removing the protective material from the leads of a replacement
ESD, touch the protective material to the chassis or circuit assembly into which the
device will be installed.
9. Minimize body motions when unpackaged replacement ESDS. Motion, such as brushing
clothes together, or lifting a foot from a carpeted floor can generate, enough static
electricity to damage an ESD.
2. Specifications
RECEPTION SYSTEM
POWER REQUIREMENTS AC 90~250V 50/60Hz(AUTO
)
POWER CONSUMPTION 130W
SOUND OUTPUT POWER 10W(R) + 10W(L) AT10% TOTAL HARMONIC DISTORTION
ANTENNA IMPEDANCE 75 OHM UNBALANCED TYPE
OPERATING FREQUENCIES
VIDEO IF 45.75MHz
SOUND IF 41.25MHz
CHANNEL COVERAGE
VHF CH : 2 ~ 13
UHF CH : 14 ~ 69
CABLE CH : 1, 14 ~ 125
CHANNEL INDICATION ON - SCREEN DISPLAY
REMOTE CONTROL UNIT REQUIRES TWO 1.5V BATTERIES TYPE AAA SIZE
PROGRAM CH MEMORY 181CH MEMORY
NTSC M, PAL M/N
STEREO BTSC - Stereo + SAP
WARNING : TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS TELEVISION
TO RAIN OR MOISTURE
3. Description of controls
1.
Video/Audio 2 In Jacks
2.
Headphone Jack
3. Channel Down ( ) Key
4. Channel Up (
) Key
5. Volume Down (-) Key
6. Volume Up (+) Key
7. Menu Key
8. TV/Video Key
9. Remote Control Sensor
10. Stand-by Indicator
11. Main Power Key
12.
Component Video Input Jacks (DVD IN)
13. Audio/Video In/Out Jacks
14.
Coaxial cable Connector (75ohm)
1
2
DVD IN
ANT.
Y
C
b
CR
345 6 7 8 9 1110
12 13 14
FRONT
2 3 4 5 6 7
8
910111
REAR
4. Alignment and Adjustments
4-1 Preadjustment
4-1-1 Factory Mode
1. Do not attempt these adjustments in the VIDEO mode.
2. The Factory Mode adjustments are necessary when either the EEPROM(IC02) or the CPT
is replaced.
3. Do not tamper with the "Adjustment" screen of the Factory Mode menu. The screen is intended
only for factory use.
4-1-2 When EEPROM (IC02) is replaced
1. When IC02 is replaced all adjustment data revert to their initial values. It is necessary to reprogram this data.
2. After IC02 is replaced, warm up the TV for 10 seconds.
4-1-3 When CPT is replaced
1. Make the following the adjustments after setting up purity and convergence:
White Balance
Vertical center
Vertical size
Horizontal size
4-2 Factory / Service Mode
4-2-1 Procedure for the "Adjustment" Mode
1. This mode uses the standard remote control. In the stand-by mode, Press
display + MENU + 3 + 8 + Power(on) button on the remote controller in --> sequence
2. The Factory Mode will be displayed. The Factory Mode has three components :
SCREEN, PICTURE SIZE, PICTURE CONTROL.
3. Access the Adjustment Mode by pressing the VOLUME keys (Up or Down). The adjustment
Parameters adjusted are listed in the accompanying table, and they are selected by pressing
the CH keys (Up or Down).
4. The VOLUME keys increase or decrease the adjustment values.
4-3 Other Adjustments
4-3-1 General Alignment Instructions
1. Usually, a color TV needs only slight touch-up adjustment upon installation. Check the
basic characteristics such as height, horizontal and vertical sync and focus.
2. Observe the picture for good black and white details. There should be no objectionable
color, shading: if color shading is present, perform the purity and convergence
adjustments described below.
3. Use the specified test equipment or its equivalent.
4. Correct impedance matching is essential.
5. Avoid overload. Excessive signal from a sweep generator might overload the front-end of
the TV. When inserting signal markers, do not allow the marker generator to distort test results.
6. Connect the TV only to an AC power source with voltage and frequency as specified on the
back cover nameplate.
7. Do not attempt to connect or disconnect any wires while the TV is turned on. Make sure that
the power cord is disconnected before replacing any parts.
8. To protect against shock hazard, use an isolation transformer.
4-3-2 Automatic Degaussing
A degaussing coil is mounted around the picture tube, so that external degaussing after
moving the TV should be unnecessary. But the receiver must be properly degaussed upon
installation .
The degaussing coil operates for about 1 second after the power is switched ON. If the set is
moved or turned in a different direction, the power should be OFF for at least 20 minutes.
If the chassis or parts of the cabinet become magnetized, poor color purity will result. If this
happens, use an external degaussing coil. Slowly move the degaussing coil around the
faceplate of the picture tube and the sides and front of the receiver. Slowly withdraw the coil to
a distance of about 6 feet before turning power OFF.
If color shading persists, perform the following Color Purity and Convergence adjustments.
4-3-3 High Voltage Check
Connect an accurate high voltmeter to the second anode of the picture tube.
Tune on the TV. Set the Brightness and Contrast controls to minimum(Zero beam current).
Adjust the Brightness and Contrast controls to both extremes. Ensure that the high voltage does
not exceed 34KV under any conditions.
4-3-4. RF AGC Adjustment
Tune in the strongest channel.
Enter input the AGC in the service mode.
Adjust AGC until color noise disappears.
CAUTION :
There is no HIGH VOLTAGE ADJUSTMENT on this chassis. But +B power must
be adjusted in +120V under the full color bar pattern and normal picture control
level.
4-3-5 Screen Voltage Adjustment
1. Turn on TV and warm up the set for 30 minutes regardless of an input signal.
2. After Sufficient warming-up, Press display + MENU + 3 + 8 + Power(on).
3. Select "SCREEN" by pressing the VOLUME keys(+,-).
4. Make white colored line by adjusting "RDC", "GDC", "BDC" as follows;
5. Adjust the Screen VR (on the FBT) so that horizontal line is just seen a little.
4-3-6 WHITE BALANCE ADJUSTMENT (MANUAL)
1. Set up : Turn the pure white pattern and warm up the set for 20 minutes.
2. Low -Light Adjustment
1-1. Turn the CONTRAST and BRIGHTNESS controls to 3.0 0.3fl with using CA100
1-2. Adjust RDC, GDC and BDC so that the levels are suitable to each local area.
1-3. Check the result of adjustment using White Balance meter.
LOW LIGHT : X=0.261, Y=0.268
3. HIGH-LIGHT Adjustment
3-1. Turn the CONTRAST and BRIGHTNESS controls to 40 4fl with using CA100
3-2. Adjust GDRV and BDRV so that the levels are suitable to each local area.
3-3. Check the result of adjustment using White Balance meter.
HIGH LIGHT : X=0.261, Y=0.268
4-3-7 FOCUS Adjustment
1. Turn in the active station in your area.
2. Press the P.STD buton on the Remote control for DYNAMIC condition.
3. In put the standard signal. (Cross-Hatch pattern)
4. Adjust the FOCUS control on the FBT to abtain a sharp and clear picture.
4-3-8 Purity Adjustment
1. Warm up the receiver for at least 30 minutes.
2. Plug in the CRT deflection yoke. Tighten the clamp screw.
3. Plug the convergence yoke into the CRT and set it as shown in Fig. B-1.
4. Input a black and white signal.
5. Fully demagnetize the receiver by using an external degaussing coil.
6. Turn the CONTRAST and BRIGHTNESS controls to maximum.
7. Loosen the clamp screw holding the yoke. Slide the yoke backward or forward to produce a
vertical green belt. (Fig. B-2)
8. Tighten the convergence yoke.
9. Slowly move the deflection yoke forward. Adjust for the best overall green screen.
10. Temporarily tighten the deflection yoke.
11. Produce blue and red rasters by adjusting the-low-light controls.
Check for good purity in each field.
12. Tighten the deflection yoke.
Cut-off Key Action Key Action
RED(1) VOL(-) RED(-) VOL(+) RED(+)
GREEN(5) VOL(-) GREEN(-) VOL(+) GREEN(+)
BLUE(9) VOL(-) BLUE(-) VOL(+) BLUE(+)
NOTE : If a white balance meter is not available than approximate the following color adjustments "
by eye".
4-3-9 Center Convergence Adjustment
1. Warm up the receiver for at least 30 minutes.
2. Adjust the two tabs of the 4-pole magnets: Change the angle between them.
Superimpose the red and blue vertical lines in the center area of the screen.
3. Adjust the BRIGHTNESS and CONTRAST controls for a well-defined picture.
4. Adjust the two tabs of the 4-pole magnets, and change the angle between them.
Superimpose the red and the blue vertical lines in the center area of the screen.
5. Turn the both tabs at the same time, keeping the angle constant, and superimpose the red
and blue horizontal lines in the center of the screen.
6. Adjust two-tabs of 6-pole magnets to superimpose the red and blue lines onto the green.
Adjust the angle affects the vertical lines, and rotating both magnets affects the horizontal lines.
7. Repeat adjustments 2-6, if necessary.
8. Since the 4-pole and 6-pole magnets interact, the dot movement is complex(fig B-3).
FIG. B-1 CONVERGENCE MAGNET ASSEMBLY
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