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28LW-92E
SERVICE MANUAL
This document has been published to
be used for after sales service only.
AK- 45 CHASSIS
In the interests of user safety (required by safety
regulations in some countries) the set should be restored to its original condition and only parts identical to those specified should be used.
CONTENTS
ELECTRICAL SPECIFICATIONS ........................................................................................ 3
IMPORTANT SERVICING NOTES ...................................................................................... 4
CONTROLS & TERMINALS ................................................................................................ 5
PRINTED WIRING BOARD LAYOUT ................................................................................. 7
PARTS LISTING ................................................................................................................... 8
HOW TO UPDATE THE TECHNICAL INFORMATION ...................................................... 11
SHARP CORPORATION
PAL B/G, I / SECAM L/L’, B/G, D/K SYSTEM COLOUR TELEVISION
MODEL 28LW-92EES
SE0028LW92E00
Issued: 22nd Jan. 2004
In order to service the model 28LW-92E , refer to
the AK-45 Chassis Service Manual
(SE00AK45CHA00).
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28LW-92E
Use this page to keep any special servicing information as Technical Report (Bulletin), Technical Information, etc.
If only part number changes are required, just change part number directly the part number in the Parts Listing Section.
If you need more information, please refer to the Technical Report (Bulletin).
SERVICE MANUAL UPDATE LOG SHEET
Part No.
Technical Report No.
Technical Bulletin No.
Cause / Solution
Page No.
Application
Data /Serial No.
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28LW-92E
ELECTRICAL SPECIFICATIONS
WARNING
The chassis in this receiver is partially hot. Use an isolation transformer between the line cord plug
and power receptacle, when servicing this chassis.
To prevent electric shock, do not remove cover. No user-serviceable parts inside. Refer servicing to
qualified service personnel.
Specifications are subject to change without prior notice.
•Power Input .................... 220V-240 Volts AC 50 Hz
•Power Consumption
Normal Operation (Method IEC60107) ............... 80 W
Stand-by Operation .......................................... < 4 W
•Audio Power Output Rating (MPO) / Impedance
Internal Left Speaker ................................. 10 W, 8 Ω
Internal Right Speaker ............................... 10 W, 8 Ω
•Speakers
2 ways speaker elliptic (2 pcs) ............ 42 x 180 mm
Tweeter (2 pcs) ................................................... 27mm
•Convergence (Maximum Misconvergence)
AREA 28” W
A0.4
BC 1.2
DE 0.8
FGHJ 1.6
KLMN 1.4
F’G’H’J’ 1.4
STUV 1.2
mm
•Picture Intermediate frequency
L’ ................................................ 33.9MHz
L, B/G, D/K,I .............................. 38.9MHz
•Sound Carrier Trap
L’ ................................................ 40.4MHz
L, D/K ......................................... 32.4MHz
B/G ............................................ 33.4MHz
I .................................................. 32.9MHz
•Adjacent Sound Carrier Trap
L’ ................................................ 32.4MHz
L, D/K, B/G ................................ 40.4MHz
I .................................................. 40.9MHz
•Adjacent Picture Carrier Trap
L’ ................................................ 41.9MHz
L, D/K, I ...................................... 30.9MHz
B/G ............................................ 31.9MHz
•Aerial Input Impedance
VHF/UHF ................. 75 ohm Unbalanced
•Tuning Ranges ..... 45.75MHz thru 855.25 MHz
VHF: IR A - J / S1 - S41 CH (Hiperband)
E2 - E12 / F2 - F10
UHF: I21 - I69 CH / E21 - E69
•White Level
Apply the rated voltage at the rated frequency to the TV set, while it is receiving full white pattern RF signal of 60
dB/µV from its RF input via the pattern generator.
Turn all picture controls to maximum value. Measure the colour temperatures at the center of the screen by
using the colour analyzer.
X=0.290 ± 0.015 Y=0.300 ± 0.015
MODEL DESTINATION (Operation Manual Languages)
28LW-92E: Deutsch, Français, Nederlands.
28LW-92EES: Español, Português.
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28LW-92E
IMPORTANT SERVICING NOTES
Only qualified service personnel are allowed to carry out maintenance and repair of this receiver.
Servicing of High Voltage System and CRT
It is important that the static charge is removed from the high voltage system when carrying out work on the
receiver. This can be achieved by connecting a 10K resistor (with a suitably insulated lead) from the CRT
cavity connector to the CRT ground tag. This must be carried out with the AC supply disconnected from the
receiver.
Note the following:
•
The CRT in this receiver employs Integral Implosion Protection.
• If the CRT has to be changed it MUST be replaced with the correct type for continued safe working.
• DO NOT lift the CRT by its neck.
• When handing the CRT, ensure that shatterproof goggles are worn.
• Ensure that the CRT is discharge before handling.
X-Ray
This receiver is designed to keep any x-ray emission to an absolute minimum. Some fault conditions and
servicing procedures may produce potentially hazardous x-ray radiation levels. This is a problem when in
close proximity to the receiver for long periods of time. To reduce any risks associated with this, please
observe the following precautions:
1. When undertaking any servicing on this chassis, DO NOT increase the EHT to more than 31 KV, (at a
instantaneous beam current of 1000 µA).
2. Ensure that during normal operation the EHT does not exceed 28 KV (at a beam current of 1200 µA).
This level has been preset in the factory. Always check that this level has not been exceeded after
carrying out any repair on the receiver.
3. DO NOT replace the CRT with any other type than that specified in the parts listing as this may cause
excessive x-ray radiation.
Before returning the receiver to the customer
In addition to the above checks, the following should also be carried out before returning the receiver to the
customer.
1. Inspect all the leads to ensure that they are dressed correctly and that they are not obstructed or pinched
by any other parts.
2. Ensure that all protective devices are in good condition. These will include nonmetallic control knobs,
insulating fish papers, cabinets backs, compartment covers or shields, mechanical insulators, etc.
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