Akai 25CT23FSR User manual

SERVICE MANUAL
Models:
25CT23FSR
29CT23FSR
www.akai.ru
COLOUR TV SET

SERVICE MANUAL
TABLE OF CONTENTS
TABLE OF CONTENTS................................................................................................... 1
SAFETY INSTRUCTIONS AND MAINTENANCE......................................... 2
X-RAY RADIATION PRECAUTION.......................................................................................... 2
SAFETY PRECAUTION.............................................................................................................. 2
PRODUCT SAFETY NOTICE.................................................................................................... 3
SAFETY SYMBOL DESCRIPTION........................................................................................... 3
MAINTENANCE............................................................................................................................ 4
ADJUSTMENTS .................................................................................................................. 5
SET-UP ADJUSTMENTS ........................................................................................................... 5
CIRCUIT ADJUSTMENTS.......................................................................................................... 8
STRUCTURE AND CHASSIS FUNCTION DESCRIPTION..................... 14
STRUCTURE BLOCK DIAGRAM ............................................................................................. 14
BLOCK DIAGRAM FOR SUPPLY VOLTAGE SYSTEM ...................................................... 15
CHASSIS DESCRIPTION ...........................................................................................................16
SERVICE DATA ..................................................................................................................17
TECHNICAL DATA OF KEY ICS ...............................................................................................17
WAVEFORMS OF KEY POINTS ...............................................................................................35
SERVICE DATA OF KEY ICS ....................................................................................................38
REPLACEMENT OF PARTS .......................................................................................44
APPENDIX
1. CIRCUIT DIAGRAM
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INSTRUCTIONS FOR SERVICE SAFETY AND MAINTENANCE
WARNING: BEFORE SERVICING THIS CHASSIS, READ THE X-RAY
RADIATION PRECAUTION , SAFETY PRECAUTION AND PRODUCT
SAFETY NOTICE INSTRUCTION BELOW.
X-RAY RADIATION PRECAUTION
1. The EHT must be checked every time the TV is serviced to ensure that the CRT does not emit
X-ray radiation as result of excessive EHT voltage. The maximum EHT voltage permissible in
any operating circumstances must not exceed the rated value. When checking the EHT, use
the High Voltage Check procedure in this manual using an accurate EHT voltmeter.
2. The only source of X-RAY radiation in this TV is the CRT. The TV minimizes X-RAY radiation,
which ensures safety during normal operation. To prevent X-ray radiation, the replacement
CRT must be identical to the original fitted as specified in the parts list.
3. Some components used in this TV have safety related characteristics preventing the CRT from
emitting X-ray radiation. For continued safety, replacement component should be made after
referring the PRODUCT SAFETY NOTICE below.
4. Service and adjustment of the TV may result in changes in the nominal EHT voltage of the
CRT anode. So ensure that the maximum EHT voltage does not exceed the rated value after
service and adjustment.
SAFETY PRECAUTION
WARNING: REFER SERVICING TO QUALIFIED SERVICE PERSONNEL ONLY.
1. The TV has a nominal working EHT voltage. Extreme caution should be exercised when
working on the TV with the back removed.
1.1 Do not attempt to service this TV if you are not conversant with the precautions and procedures
for working on high voltage equipment.
1.2 When handling or working on the CRT, always discharge the anode to the TV chassis before
removing the anode cap in case of electric shock.
1.3 The CRT, if broken, will violently expel glass fragments. Use shatterproof goggles and take
extreme care while handling.
1.4 Do not hold the CRT by the neck as this is a very dangerous practice.
2. It is essential that to maintain the safety of the customer all power cord forms be replaced
exactly as supplied from factory.
3. Voltage exists between the hot and cold ground when the TV is in operation. Install a suitable
isolating transformer of beyond rated overall power when servicing or connecting any test
equipment for the sake of safety.
4. When replacing ICs, use specific tools or a static-proof electric iron with small power (below
35W).
5. Do not use a magnetized screwdriver when tightening or loosing the deflection yoke assembly
to avoid electronic gun magnetized and decrement in convergence of the CRT.
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6. When remounting the TV chassis, ensure that all guard devices, such as nonmetal control
buttons, switch, insulating sleeve, shielding cover, isolating resistors and capacitors, are
installed on the original place.
7. Replace blown fuses within the TV with the fuse specified in the parts list.
8. When replacing wires or components to terminals or tags, wind the leads around the terminal
before soldering. When replacing safety components identified by the international hazard
symbols on the circuit diagram and parts list, it must be the company-approved type and must
be mounted as the original.
9. Keep wires away from high temperature components.
PRODUCT SAFETY NOTICE
CAUTION: FOR YOUR PROTECTION, THE FOLLOWING PRODUCT SAFETY NOTICE
SHOULD BE READ CAREFULLY BEFORE OPERATING AND SERVICING THIS TV SET.
1. Many electrical and mechanical components in this chassis have special safety-related
characteristics. These characteristics are often passed unnoticed by a visual inspection and
the X-ray radiation protection afforded by them cannot necessarily be obtained by using
replacements rated at higher voltages or wattage, etc. Components which have these special
safety characteristics in this manual and its supplements are identified by the international
hazard symbols on the circuit diagram and parts list. Before replacing any of these components
read the parts list in this manual carefully. Substitute replacement components which do not
have the same safety characteristics as specified in the parts list may create X-ray radiation.
2. Do not slap or beat the cabinet or CRT, since this may result in fire or explosion.
3. Never allow the TV sharing a plug or socket with other large-power equipment. Doing so may
result in too large load, causing fire.
4. Do not allow anything to rest on or roll over the power cord. Protect the power cord from being
walked on, modified, cut or pinched, particularly at plugs.
5. Do not place any objects, especially heavy objects and lightings, on top of the TV set. Do not
install the TV near any heat sources such as radiators, heat registers, stove, or other
apparatus that produce heat.
6. Service personnel should observe the SAFETY INSTRUCTIONS in this manual during use and
servicing of this TV set. Otherwise, the resulted damage is not protected by the manufacturer.
SAFETY SYMBOL DESCRIPTION
The lightning symbol in the triangle tells you that the voltage inside this product
may be strong enough to cause an electric shock. Extreme caution should be
exercised when working on the TV with the back removed.
This is an international hazard symbol, telling you that the components identified
by the symbol have special safety-related characteristics.
FDA This symbol tells you that the critical components identified by the FDA marking
have special safety-related characteristics.
ULThis symbol tells you that the critical components identified by the UL marking
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have special safety-related characteristics.
C UL This symbol tells you that the critical components identified by the C-UL marking
have been evaluated to the UL and C-UL standards and have special
safety-related characteristics.
VDE This symbol tells you that the critical components identified by the VDE marking
have special safety-related characteristics.
MAINTENANCE
1. Place the TV set on a stable stand or base that is of adequate size and strength to prevent it
from being accidentally tipped over, pushed off, or pulled off. Do not place the set near or
over a radiator or heat register, or where it is exposed to direct sunlight.
2. Do not install the TV set in a place exposed to rain, water, excessive dust, mechanical
vibrations or impacts.
3. Allow enough space (at least 10cm) between the TV and wall or enclosures for proper
ventilation.
4. Slots and openings in the cabinet should never be blocked by clothes or other objects.
5. Please power off the TV set and disconnect it from the wall immediately if any abnormal
condition are met, such as bad smell, belching smoke, sparkling, abnormal sound, no
picture/sound/raster. Hold the plug firmly when disconnecting the power cord.
6. Unplug the TV set from the wall outlet before cleaning or polishing it. Use a dry soft cloth for
cleaning the exterior of the TV set or CRT screen. Do not use liquid cleaners or aerosol
cleaners.
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