Sharp 28LF-94E User manual

1
28LF-94E
SERVICE MANUAL
This document has been published to
be used for after sales service only.
AK-53 CHASSIS
In the interests of user safety (required by safety
regulations in some countries) the set should be re-
stored to its original condition and only parts identi-
cal to those specified should be used.
CONTENTS
ELECTRICAL SPECIFICATIONS ........................................................................................ 3
IMPORTANT SERVICING NOTES ...................................................................................... 4
CONTROLS & TERMINALS ................................................................................................ 5
PRINTED WIRING BOARD LAYOUT ................................................................................. 7
PARTS LISTING ................................................................................................................... 9
HOW TO UPDATE THE TECHNICAL INFORMATION ...................................................... 19
SHARP CORPORATION
SE0028LF94S00
Issued: 7th July 2004
In order to service the model 28LF-94E, refer to
the AK-53 Chassis Service Manual
(SE00AK53CHA00).
MODEL 28LF-94E
PAL B/G / SECAM L/L’, B/G, D/K SYSTEM COLOUR TELEVISION

2
28LF-94E
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.

3
28LF-94E
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.
•Picture Intermediate frequency
L’ ................................................ 33.9MHz
L, B/G, D/K ................................. 38.9MHz
•Sound Carrier Trap
L’ ................................................ 40.4MHz
L, D/K ......................................... 32.4MHz
B/G ............................................ 33.4MHz
•Adjacent Sound Carrier Trap
L’ ................................................ 32.4MHz
L, D/K, B/G ................................ 40.4MHz
•Adjacent Picture Carrier Trap
L’ ................................................ 41.9MHz
L, D/K ........................................ 30.9MHz
B/G ............................................ 31.9MHz
•Aerial Input Impedance
VHF/UHF ................. 75 ohm Unbalanced
•Tuning Ranges ..... 48.25MHz thru 855.25 MHz
VHF: S1 - S41 CH (Hiperband)
E2 - E12 / F2 - F10
UHF: E21 - E69
•Power Input .................... 220V-240 Volts AC 50 Hz
•Power Consumption
Normal Operation (Method IEC60107) ............. 113 W
Stand-by Operation .......................................... < 3 W
•Audio Power Output Rating (MPO) / Impedance
Internal Left Speaker ................................. 10 W, 7 Ω
Internal Right Speaker ............................... 10 W, 7 Ω
•Speakers
Full range (2 pcs) ................................... 60 x 120 mm
•Convergence (Maximum Misconvergence)
MODEL DESTINATION (Operation Manual Languages)
28LF-94E: Deutsch, Français, Nederlands.
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
•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

4
28LF-94E
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 33 KV (at a
instantaneous beam current of 1800 µA).
2. Ensure that during normal operation the EHT does not exceed 29,65 KV (at a beam current of 1800 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.

5
28LF-94E
CONTROLS & TERMINALS
VIDEO
AUDIO L (L/S/G/I) = Audio left
AUDIO R (R/D/D/D) = Audio right
= Headphone 3,6 mm Ø
Speakers (left + right)
= ower On / Off
= Volume -/+
CH = rogram -/+
S-VIDEO
&+
&+ 69,'(2 9,'( 2 /6*,

5'''
$8', 2
69,'(2 9,'(2 /6*,

5'''
$8',2
FRONT PANEL
REAR TV
RF Input
1. Aerial terminal
21-pin In/Out
2. 21-pin Audio/Video (RGB) (EXT.1) With
AL/SECAM/NTSC/S-Video Input
3. 21-pin Audio/Video (EXT.2) With
AL/SECAM/NTSC Video Input
(;7
(;7


6
28LF-94E
REMOTE CONTROL
1
= Stand By
= Cursor Up
= Cursor Right
OK = Store / Still icture
= Info ( rogram Table)
- 9 = Direct rogram
- / - - = Double Digit
= Screen Format button
P/CH+ = rogram Up
+ = Volume Up
= TV / Quit Menu
(;7
= EXT button (EXT-1, EXT-2, S-VHS, S-VHS EXT2 or FRONT-AV)
Yellow = Feature Menu
Blue = Installation Menu
= Hold
16
= Update
= Index age
= Reveal
= Expand
= Mix
21
= Teletext
= Time
23
Red = Sound Menu
Green = icture Menu
= Mute
I-II = Mono/Stereo - Dual I-II
- = Volume Down
- P/CH = rogram Down
= Flash back button
30
M = Menu
31
= Cursor Down
32
= Cursor Left

7
28LF-94E
CHASSIS LAYOUT
Mother Unit
Front Unit (SW+Keyboard+FAV)

8
28LF-94E
Digital Module Unit
CRT Socket Unit

9
28LF-94E
PARTS LISTING
REPLACEMENT PARTS
Replacement parts which have special safety characteristics are identified in
this manual. Electrical components having such features are identified by
in the Replacement Parts Listing.
The use of a substitute replacement part which does not have the same safety
characteristics as the factory recommended is not permitted.
Replacement parts not shown in this service manual may create shock fire, or
other hazards.
HOW TO ORDER REPLACEMENT PARTS
To have your order completed promptly and correctly please supply the follow-
ing information.
1. MODEL NUMBER 2. REF. NO.
3. PART NO. (*) 4. DESCRIPTION
5. CODE 6. QUANTITY
(*) When ordering any part, a “V” should be added before the Part No.
(*)
REF No. PARTS DESCRIPTION SN CODE EX CODE
Q117 30001458 TR BC858B SMD AA AB
Q400 30001458 TR BC858B SMD AA AB
Q401 30001457 TR BC848B SMD AA AC
Q402 30001457 TR BC848B SMD AA AC
Q403 30001457 TR BC848B SMD AA AC
Q404 30001457 TR BC848B SMD AA AC
Q405 30001458 TR BC858B SMD AA AB
Q406 30001458 TR BC858B SMD AA AB
Q412 30001457 TR BC848B SMD AA AC
Q413 30001457 TR BC848B SMD AA AC
Q700 30001458 TR BC858B SMD AA AB
Q701 30001457 TR BC848B SMD AA AC
Q702 30001457 TR BC848B SMD AA AC
Q703 30001457 TR BC848B SMD AA AC
Q704 30001457 TR BC848B SMD AA AC
Q706 30001457 TR BC848B SMD AA AC
Q707 30001458 TR BC858B SMD AA AB
Q708 30001457 TR BC848B SMD AA AC
Q709 30001458 TR BC858B SMD AA AB
Q710 30001458 TR BC858B SMD AA AB
Q711 30001457 TR BC848B SMD AA AC
Q712 30001458 TR BC858B SMD AA AB
Q713 30001458 TR BC858B SMD AA AB
Q714 30001457 TR BC848B SMD AA AC
Q715 30001458 TR BC858B SMD AA AB
Q716 30001458 TR BC858B SMD AA AB
Q717 30001457 TR BC848B SMD AA AC
Q718 30001458 TR BC858B SMD AA AB
Q719 30001457 TR BC848B SMD AA AC
Q720 30001457 TR BC848B SMD AA AC
Q722 30001458 TR BC858B SMD AA AB
Q725 30001457 TR BC848B SMD AA AC
Q729 30001458 TR BC858B SMD AA AB
Q733 30001457 TR BC848B SMD AA AC
Q734 30001458 TR BC858B SMD AA AB
Q735 30001457 TR BC848B SMD AA AC
Q801 30001454 TR BC548B AA AC
Q802 30001386 TR MTP6N60E (PLASTIC) AE AP
Q803 30001454 TR BC548B AA AC
Q804 30001457 TR BC848B SMD AA AC
Q805 30001454 TR BC548B AA AC
Q806 30001428 TR BF423 AA AC
Q807 30001457 TR BC848B SMD AA AC
Q808 30001457 TR BC848B SMD AA AC
Q810 30001454 TR BC548B AA AC
Q811 30001457 TR BC848B SMD AA AC
Q812 30001458 TR BC858B SMD AA AB
Q813 30007802 TR STP20N06LFP AD AL
Q814 30001455 TR BC558B AA AC
Q815 30023137 IC TL431 %1 TOL (TO-92) AA AD
Q816 30023137 IC TL431 %1 TOL (TO-92) AA AD
Q817 30001384 TR MCR22-6 AB AG
Q818 30010149 TR BD243C AC AG
Q900 30001427 TR BF422 AA AE
Q902 30017863 TR BF199 AA AD
Q903 30017862 TR BF370 AA AE
Q904 30003768 TR BD139 AB AF
Q905 30013531 TR BD140 AB AF
Q906 30017863 TR BF199 AA AD
DIODES
D100 30001291 DIODE HER107 1A/800V 30A AA AB
D100 30003720 DIODE ZENER BZT55C5V6 5.6V SMD AA AB
D100 20060150 BRACKET LED 20 AA AD
D100 30001279 LED RED/GREEN LTL293SJ AC AH
D101 30001371 DIODE ZENER 5.1V ZPD AA AB
REF No. PARTS DESCRIPTION SN CODE EX CODE
. 30016949 28" CPT TUBE 16:9 100HZ REALFLAT CE CZ
. 30029092 28" 16:9 RF DEG COIL&EARTH CB. WO/UL S AL AX
TUNER
TU200 30009637 TUNER WSP (PLL) CTF5510A AR BC
INTEGRATED CIRCUITS
IC100 30013687 IC TDA8177F AH AT
IC100 30001669 PREAMPLIFIER TFMS1380 AD AM
IC103 30022479 IC LDO LM1086 3.3V/1.5A D2PAK VINMAX=18V AC AK
IC104 30022477 IC STEP DOWN CS51033 1A SO8 AE AP
IC105 30001665 IC LM358N AA AE
IC105 30022958 TR PMOS STS5PF30L -5A/-30V SO8 AB AF
IC309 20164379 IC M24C64 D01341111172111221111 AC AK
IC309 30021752 IC M24C64 (SO8W6) AD AK
IC313 30021602 IC PNX3006E / N302 BC BS
IC314 30027713 IC FLASH 32Mbit 3V x8/x16 (TSOP-56) AQ BB
IC315 30029152 IC SDRAM 64MBIT(1Mx16bitx4bank)TSOP(CTV) AR BC
IC316 30022895 IC RESET NE56610-29 AD AL
IC400 30021285 IC PNX3000HL / N2 AS BD
IC401 30018422 IC AAMP TDA7480L 10W PDIP20 AG AS
IC402 30018422 IC AAMP TDA7480L 10W PDIP20 AG AS
IC801 30015087 IC SAFE OPTOCOUPLER TCET1102G AA AE
IC803 30001500 IC LM7808 AC AH
IC804 30011968 IC SMPS MC44608 DIP8 AF AQ
IC900 30008721 IC TDA6108 AH AT
TRANSISTORS
Q100 30018627 TR NMOS IRFU110 4.3A/100V TO251 AB AG
Q101 30016686 TR 2SC5302 AK AV
Q102 30001458 TR BC858B SMD AA AB
Q102 30001457 TR BC848B SMD AA AC
Q103 30001458 TR BC858B SMD AA AB
Q103 30001457 TR BC848B SMD AA AC
Q104 30007799 TR BDX53BFI AC AK
Q105 30001454 TR BC548B AA AC
Q106 30001458 TR BC858B SMD AA AB
Q106 30025524 TR PMEM4010PD PNP/SCH -1A -40V SOT457 AB AF
Q107 30001452 TR BC327 AA AC
Q108 30001457 TR BC848B SMD AA AC
Q109 30001452 TR BC327 AA AC
Q110 30001453 TR BC337 AA AC
Q111 30001453 TR BC337 AA AC
Q112 30001457 TR BC848B SMD AA AC
Q113 30001457 TR BC848B SMD AA AC
Q114 30001457 TR BC848B SMD AA AC
Q115 30001458 TR BC858B SMD AA AB
Q116 30023137 IC TL431 %1 TOL (TO-92) AA AD
PICTURE TUBE
!
!
!

10
28LF-94E
REF No. PARTS DESCRIPTION SN CODE EX CODE
D102 30007760 DIODE ZENER SMD BZT55C10 AA AB
D102 30018574 DIODE SCH SS33 3A/30V DO214AB AA AE
D102 30001371 DIODE ZENER 5.1V ZPD AA AB
D103 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D103 30001371 DIODE ZENER 5.1V ZPD AA AB
D104 30007678 DIODE GUC DTV32F1500A 6A/1500V 100A AD AL
D104 30001371 DIODE ZENER 5.1V ZPD AA AB
D105 30007768 DIODE STTA506F 5A/600V 55A AD AM
D105 30001371 DIODE ZENER 5.1V ZPD AA AB
D106 30001291 DIODE HER107 1A/800V 30A AA AB
D106 30001371 DIODE ZENER 5.1V ZPD AA AB
D107 30001291 DIODE HER107 1A/800V 30A AA AB
D107 30001371 DIODE ZENER 5.1V ZPD AA AB
D108 30001299 DIODE UF5404 3A/400V 150A AA AD
D109 30001299 DIODE UF5404 3A/400V 150A AA AD
D110 30001291 DIODE HER107 1A/800V 30A AA AB
D111 30001288 DIODE BYV27-200 2A/200V 50A AA AD
D112 30012412 DIODE ZENER 2.4V SMD AA AB
D113 30001377 DIODE ZENER 33V UZT 33B AB AF
D114 30001285 DIODE 1N4148 SMD AA AB
D117 30001285 DIODE 1N4148 SMD AA AB
D118 30001285 DIODE 1N4148 SMD AA AB
D119 30001285 DIODE 1N4148 SMD AA AB
D120 30001318 DIODE BA159 1A/800V 20A AA AB
D121 30009699 DIODE ZENER SMD BZT55C12 AA AB
D122 30009699 DIODE ZENER SMD BZT55C12 AA AB
D123 30001318 DIODE BA159 1A/800V 20A AA AB
D124 30009699 DIODE ZENER SMD BZT55C12 AA AB
D125 30001291 DIODE HER107 1A/800V 30A AA AB
D127 30001285 DIODE 1N4148 SMD AA AB
D128 30001285 DIODE 1N4148 SMD AA AB
D201 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D202 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D203 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D204 30018735 DIODE ZENER BZT55C15 15V SMD AA AB
D205 30018735 DIODE ZENER BZT55C15 15V SMD AA AB
D207 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D400 30012411 DIODE BA782 SMD AA AD
D404 30001284 DIODE 1N4148 0.15A/100V 0.5A AA AB
D700 30001285 DIODE 1N4148 SMD AA AB
D701 30001285 DIODE 1N4148 SMD AA AB
D703 30021518 DIODE ZENER BZT55C2V7 2.7V SMD AA AA
D705 30021443 DIODE ZENER BZT55C22 22V SMD AA AA
D707 30021445 DIODE ZENER BZT55C47 47V SMD AA AA
D711 30001285 DIODE 1N4148 SMD AA AB
D713 30022478 DIODE SCH BAT254 0.2A/30V SOD110 AA AC
D714 30007169 DIODE BAV99 (SOT23) 0.25A/70V 4.5A AA AA
D715 30007169 DIODE BAV99 (SOT23) 0.25A/70V 4.5A AA AA
D716 30001285 DIODE 1N4148 SMD AA AB
D717 30001285 DIODE 1N4148 SMD AA AB
D718 30001285 DIODE 1N4148 SMD AA AB
D801 30001318 DIODE BA159 1A/800V 20A AA AB
D802 30001323 DIODE BY299 2A/800V 70A AA AD
D803 30009366 DIODE UF5402 3A/200V 150A AB AF
D804 30009366 DIODE UF5402 3A/200V 150A AB AF
D805 30007681 DIODE UF5407 3A/800V 150A AB AF
D805+ 30001964 FERRITE BAR 5*8 AA AD
D806 30001344 DIODE ZENER 6.2V 1/2W AA AB
D807 30000613 RES SMD 1/8W 2.4K G AA AA
D808 30001288 DIODE BYV27-200 2A/200V 50A AA AD
D809 30001285 DIODE 1N4148 SMD AA AB
D810 20108354 DIODE BRIDGE GBU4M 4A/1000V 150A(FORMLU) AB AE
D811 30009366 DIODE UF5402 3A/200V 150A AB AF
D812 30001329 DIODE 1N4007 1A/1000V 30A AA AB
D813 30006691 DIODE ZENER 3.3V AA AA
D814 30001318 DIODE BA159 1A/800V 20A AA AB
REF No. PARTS DESCRIPTION SN CODE EX CODE
D815 30001318 DIODE BA159 1A/800V 20A AA AB
D818 30001318 DIODE BA159 1A/800V 20A AA AB
D819 30001285 DIODE 1N4148 SMD AA AB
D820 30001285 DIODE 1N4148 SMD AA AB
D821 30001285 DIODE 1N4148 SMD AA AB
D822 30009699 DIODE ZENER SMD BZT55C12 AA AB
D823 30001285 DIODE 1N4148 SMD AA AB
D824 30009366 DIODE UF5402 3A/200V 150A AB AF
D827 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D829 30001318 DIODE BA159 1A/800V 20A AA AB
D830 30001285 DIODE 1N4148 SMD AA AB
D831 30001329 DIODE 1N4007 1A/1000V 30A AA AB
D901 30001318 DIODE BA159 1A/800V 20A AA AB
D902 30001318 DIODE BA159 1A/800V 20A AA AB
D903 30001318 DIODE BA159 1A/800V 20A AA AB
D904 30001318 DIODE BA159 1A/800V 20A AA AB
D905 30001284 DIODE 1N4148 0.15A/100V 0.5A AA AB
D906 30001284 DIODE 1N4148 0.15A/100V 0.5A AA AB
D907 30001284 DIODE 1N4148 0.15A/100V 0.5A AA AB
D910 30006918 DIODE BAV21 0.25A/200V 1A AA AB
D911 30006918 DIODE BAV21 0.25A/200V 1A AA AB
D951 30001285 DIODE 1N4148 SMD AA AB
D965 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D966 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D967 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D968 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D969 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D970 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D971 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D972 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D973 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
D974 30007763 DIODE ZENER SMD BZT55C5V1 AA AB
PACKAGED CIRCUITS
X700 30022663 XTAL 13.5MHZ AA AD
COILS
L100 30007771 FIXED COIL 100UH AA AE
L100 30001979 FIXED COIL 1UH Q45 M-A AA AB
L1000 30001992 FIXED COIL 10UH Q65 K-A AA AB
L1001 30001992 FIXED COIL 10UH Q65 K-A AA AB
L101 30007757 COIL INJECTION EW 6MH AK28 AC AH
L101 30023096 FIXED COIL SMD 10uH 2.5A 10x10x4.5mm AC AG
L101 30001979 FIXED COIL 1UH Q45 M-A AA AB
L102 30022848 FERRITE SMD 30/100MHz 4A (0603) AA AC
L103 30020531 FERRITE SMD (805) BLM21PG221SN1 AA AA
L104 30020531 FERRITE SMD (805) BLM21PG221SN1 AA AA
L104 30019483 COIL BRIDGE 300UH 32KHZ AK52 AD AM
L105 30006712 FERRITE BEAD 3.5X4.7X0.8 AA AB
L106 30006712 FERRITE BEAD 3.5X4.7X0.8 AA AB
L107 30001996 FIXED COIL 22UH Q40 K AA AB
L107 30020531 FERRITE SMD (805) BLM21PG221SN1 AA AA
L108 30001996 FIXED COIL 22UH Q40 K AA AB
L108 30020531 FERRITE SMD (805) BLM21PG221SN1 AA AA
L109 30001996 FIXED COIL 22UH Q40 K AA AB
L109 30020531 FERRITE SMD (805) BLM21PG221SN1 AA AA
L112 30018093 COIL SMD 3.3uH (2520) AA AC
L113 30018093 COIL SMD 3.3uH (2520) AA AC
L114 30018093 COIL SMD 3.3uH (2520) AA AC
L115 30020531 FERRITE SMD (805) BLM21PG221SN1 AA AA
L213 30013413 FERRITE BEAD ACB2012H-300 AA AB
L214 30013413 FERRITE BEAD ACB2012H-300 AA AB
L215 30013413 FERRITE BEAD ACB2012H-300 AA AB
L216 30013413 FERRITE BEAD ACB2012H-300 AA AB
L217 30013413 FERRITE BEAD ACB2012H-300 AA AB
L218 30013413 FERRITE BEAD ACB2012H-300 AA AB