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1
ENGLISH ............................................................................................................................................. 3
SAFETY ............................................................................................................................................ 3
SAFETY PRECAUTIONS ..............................................................................................................................3
CIRCUIT DESCRIPTION ................................................................................................................... 4
D8/A8 CHASSIS ALIGNMENT PROCEDURE ................................................................................................4
DIGITAL COMB FILTER ­ TOSHIBA TC9090AF. ......................................................................................... 13
SCAN VELOCITY MODULATION. ............................................................................................................... 13
DIGITAL DOUBLE SCAN CONVERSION UNIT (FEATURE BOX)................................................................. 13
INPUT PROCESSOR - PHILIPS TDA 9320. ................................................................................................. 14
PICTURE IMPROVEMENT - PHILIPS TDA 9178.......................................................................................... 15
TUNER........................................................................................................................................................ 15
RGB PROCESSOR - TDA 9330................................................................................................................... 15
SIGNAL PATH DESCRIPTION..................................................................................................................... 16
AUDIO CIRCUIT.......................................................................................................................................... 16
AUDIO OUTPUT.......................................................................................................................................... 17
DOLBY DECODER...................................................................................................................................... 17
DEFLECTION.............................................................................................................................................. 17
HIGH END FEATURE BOX.......................................................................................................................... 18
LOW END FEATURE BOX .......................................................................................................................... 18
MICROCONTROLLER SECTION ON THE A8/D8 CHASSIS ........................................................................ 19
POWERED CONSOLE ................................................................................................................................ 26
DIGITAL SECTION ...................................................................................................................................... 27
GENERAL BLOCK DIAGRAM...................................................................................................................... 28
COFDM FRONT-END PCB.......................................................................................................................... 29
MPEG DECODER AND AV/GRAPHICS PCB ............................................................................................... 37
CONNECTOR SPECIFICATION .................................................................................................................. 60
A8/D8 PSU.................................................................................................................................................. 66
DTI PSU...................................................................................................................................................... 67
SERVICING..................................................................................................................................... 69
SERVICE. ................................................................................................................................................... 69
SELF DIAGNOSTICS .................................................................................................................................. 71
DIAGNOSTIC INTERFACE.......................................................................................................................... 73
FRANÇAIS ......................................................................................................................................... 74
SÉCURITÉ ...................................................................................................................................... 74
CONSIGNES DE SECURITE ....................................................................................................................... 74
DESCRIPTION DU CIRCUIT ........................................................................................................... 75
PROCEDURE D'ALIGNEMANT DU COFFRET D8/A8 .................................................................................. 75
FILTRE-PEIGNE NUMÉRIQUE.................................................................................................................... 84
MODULATION DE LA VITESSE DE BALAYAGE.......................................................................................... 84
GROUPE DE CONVERSION NUMÉRIQUE À DOUBLE VISIONNEMENT (COFFRET DES FONCTIONS). ... 84
PROCESSEUR D'ENTRÉE ­ PHILIPS TDA 9320 ........................................................................................ 85
AMÉLIORATION DE L'IMAGE - PHILIPS TDA 9178 ..................................................................................... 86
TUNER........................................................................................................................................................ 86
PROCESSEUR RGB - TDA 9330................................................................................................................. 86
DESCRIPTION DE LA TRAJECTOIRE DES SIGNAUX ................................................................................ 87
CIRCUIT AUDIO.......................................................................................................................................... 87
SORTIE AUDIO........................................................................................................................................... 88
DÉCODEUR DOLBY ................................................................................................................................... 88
DEFLEXION ................................................................................................................................................ 89
CASE DE FONCTIONS EXTRÉMITÉ HAUTE .............................................................................................. 90
CASE FONCTIONS EXTRÉMITÉ BASSE .................................................................................................... 90
SECTION DU MICROCONTRÔLEUR DU CHÂSSIS A8/D8 .......................................................................... 91
CONSOLE D'ALIMENTATION ..................................................................................................................... 99
DESCRIPTION GÉNÉRALE ...................................................................................................................... 100
SCHÉMA SYNOPTIQUE ........................................................................................................................... 101
CIRCUIT IMPRIMÉ FRONTAL COFDM...................................................................................................... 102
CIRCUIT IMPRIMÉ DE DÉCODEUR MPEG ET AV/GRAPHIQUES ............................................................ 110
SPÉCIFICATION DES CONNECTEURS .................................................................................................... 132
ALIMENTATION A8/D8.............................................................................................................................. 139
ALIMENTATION DTI.................................................................................................................................. 140
ENTRETIEN COURANT ................................................................................................................ 142
SERVICE. ................................................................................................................................................. 142
AUTO-DIAGNOSTIC.................................................................................................................................. 146


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2
INTERFACE DE DIAGNOSTIC. ................................................................................................................. 148
DEUTSCH........................................................................................................................................ 149
SICHERHEIT................................................................................................................................. 149
SICHERHEITSVORKEHRUNGEN ............................................................................................................. 149
SCHALTUNGSBESCHREIBUNG .................................................................................................. 150
D8/A8 VERFAHREN ZUM GRUNDPLATTENABGLEICH ........................................................................... 150
DIGITALER KAMMFILTER ­ TOSHIBA TC9090AF. ................................................................................... 159
MODULATION DER ABTAST-GESCHWINDIGKEIT................................................................................... 159
DIGITALES DOPPELABTASTUNGS-UMWANDLUNGS-AGGREGAT (ZUSATZ-KASTEN). ........................ 159
EINGABE-PROZESSOR - PHILIPS TDA 9320. .......................................................................................... 160
BILDVERBESSERUNG - PHILIPS TDA 9178. ............................................................................................ 161
TUNER...................................................................................................................................................... 161
RGB PROZESSOR - TDA 9330. ................................................................................................................ 161
BESCHREIBUNG DES SIGNALWEGS. ..................................................................................................... 162
AUDIO-SCHALTKREIS.............................................................................................................................. 162
AUDIO-AUSGABE ..................................................................................................................................... 163
DOLBY DECODER.................................................................................................................................... 163
ABLENKUNG ............................................................................................................................................ 163
,,HÖHERE" FEATURE BOX ....................................................................................................................... 165
,,NIEDRIGE" FEATURE BOX...................................................................................................................... 165
MIKROCONTROLLER-ABSCHNITT AUF DER A8/D8 GRUNDPLATTE...................................................... 166
MIT STROM VERSORGTE KONSOLE ...................................................................................................... 175
DIGITALER TEIL ....................................................................................................................................... 175
BLOCKSCHALTBILD................................................................................................................................. 177
COFDM EINGANGS-FLACHBAUGRUPPE ................................................................................................ 178
MPEG DECODER UND AV/GRAFIK FLACHBAUGRUPPE ........................................................................ 187
STECKER-SPEZIFIKATION ...................................................................................................................... 210
A8/D8 NETZTEIL....................................................................................................................................... 217
DTI-NETZTEIL........................................................................................................................................... 218
WARTUNG.................................................................................................................................... 220
WARTUNG................................................................................................................................................ 220
SELBST-DIAGNOSE. ................................................................................................................................ 223
DIAGNOSE-SCHNITTSTELLE................................................................................................................... 224
WAVEFORMS ............................................................................................................................... 225
IC DATA ........................................................................................................................................ 230
I200........................................................................................................................................................... 230
IE02 .......................................................................................................................................................... 235
MECHANICAL ............................................................................................................................... 238


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3
ENGLISH
ENGLISH
SAFETY
SAFETY PRECAUTIONS
WARNING: The following precautions must be observed.
ALL PRODUCTS
1.
Before any service is performed on the chassis an isolation transformer should be inserted between the power line and
the product.
2.
When replacing the chassis in the cabinet, ensure all the protective devices are put back in place.
3.
When service is required, observe the original lead dressing. Extra precaution should be taken to ensure correct lead
dressing in any high voltage circuitry area.
4.
Many electrical and mechanical parts in HITACHI products have special safety related characteristics. These
characteristics are often not evident from visual inspection, nor can the protection afforded by them necessarily be
obtained by using replacement components rated for higher voltage, wattage, etc. Replacement parts which have these
special safety characteristics are identified by marking with a
! on the schematics and the replacement parts list.
The use of a substitute replacement component that does not have the same safety characteristics as the HITACHI
recommended replacement one, shown in the parts list, may create electrical shock, fire, X-radiation, or other hazards.
5.
Always replace original spacers and maintain lead lengths. Furthermore, where a short circuit has occurred, replace those
components that indicate evidence of overheating.
6.
Insulation resistance should not be less than 2M ohms at 500V DC between the main poles and any accessible metal
parts.
7.
No flashover or breakdown should occur during the dielectric strength test, applying 3kV AC or 4.25kV DC for two
seconds between the main poles and accessible metal parts.
8.
Before returning a serviced product to the customer, the service technician must thoroughly test the unit to be certain that
it is completely safe to operate without danger of electrical shock. The service technician must make sure that no
protective device built into the instrument by the manufacturer has become defective, or inadvertently damaged during
servicing.
CE MARK
1.
HITACHI products may contain the CE mark on the rating plate indicating that the product contains parts that have been
specifically approved to provide electromagnetic compatibility to designated levels.
2.
When replacing any part in this product, please use only the correct part itemised in the parts list to ensure this standard
is maintained, and take care to replace lead dressing to its original state, as this can have a bearing on the
electromagnetic radiation/immunity.
PICTURE TUBE
1.
The line output stage can develop voltages in excess of 25kV; if the E.H.T. cap is required to be removed, discharge the
anode to chassis via a high value resistor, prior to its removal from the picture tube.
2.
High voltage should always be kept at the rated value of the chassis and no higher. Operating at higher voltages may
cause a failure of the picture tube or high voltage supply, and also, under certain circumstances could produce X-radiation
levels moderately in excess of design levels. The high voltage must not, under any circumstances, exceed 29kV on the
chassis (except for projection Televisions).
3.
The primary source of X-radiation in the product is the picture tube. The picture tube utilised for the above mentioned
function in this chassis is specially constructed to limit X-radiation. For continued X-radiation protection, replace tube with
the same type as the original HITACHI approved type
4.
Keep the picture tube away from the body while handling. Do not install, remove, or handle the picture tube in any manner
unless shatterproof goggles are worn. People not so equipped should be kept away while picture tubes are handled
LASERS
If the product contains a laser avoid direct exposure to the beam when the cover is open or when interlocks are defeated or have
failed.CIRCUIT DESCRIPTIONCIRCUIT DESCRIPTION


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4
CIRCUIT DESCRIPTION
D8/A8 CHASSIS ALIGNMENT PROCEDURE
APPLICATIONS
THIS SPEC. SHOULD BE APPLIED TO ALL UK AND EXPORT, A8 RECEIVERS
P.W.B ASSEMBLY ADJUSTMENT
FOR SIGNAL
PREPARATION ADJUSTMENT
·
+B adj. VR982..........Centre
·
Screen VR (FBT).......Counter-clockwise fully
·
Turn on set. Adjust +B to approximately 152V. (Pre adjustment only - final adjustment in +B VOLTAGE ADJUSTMENT
section)
·
If flaring is observed adjust L501 until a clean video signal is seen on the oscilloscope video out port.
For models which have a flash device fitted, ensure that the service information reads FLASH: x.x instead of Code: x.x for the
software version.
STANDARD AFC ALIGNMENT
To reduce the influence of circuit temperature drift, let the television warm up by leaving it operating normally for more than two
minutes.
·
Receive a 'PAL I' signal by selecting program 3 via the remote control handset.
·
Receive a signal level of +60 dBuV at 623,25MHz (CH40) by direct frequency entry under the CH option.
·
Set AFC offset (in service - options) to the centre position.
·
In the tuner menu select standard I.F AFC and press either '<' or '>' on the remote control to activate the automatic AFC
setting procedure.
·
If the indicator bar goes either end, then returns to the centre, adjust L201 one turn and then return to step 3, continue this
until the indicator bar no longer jumps back to the centre.
L' AFC ALIGNMENT (FOR EXPORT MODELS ONLY).
·
To reduce the influence of circuit temperature drift, let the television warm up by leaving it operating normally for more
than two minutes.
·
Receive an L' signal by selecting program 14 via the remote control hand-set.
·
Receive a signal level of +60 dBuV at 63,75MHz (CH4) by direct frequency entry under the CH option.
·
In the tuner menu select L' I.F AFC and press '<' or '>' on the remote control.
·
If the bar goes to either end then returns to centre, adjust L201 one turn and then return to step 3, continue this until the
indicator bar no longer jumps back to the centre.
Because the set up procedures are interactive it is necessary to repeat all procedures from STANDARD AFC ALIGNMENT until no
adjustment of L201 is required.
AGC ALIGNMENT
·
To reduce the influence of circuit temperature drift, let the television warm up by leaving it operating normally for more
than two minutes.
·
Connect a voltmeter of at least 100K internal resistance to the A.G.C. terminal of the tuner.
·
Receive channel 40 (623.25mhz) at +60dBuV.
·
Adjust the A.G.C. using the A.G.C take-over option in the tuner sub menu until the A.G.C. voltage is 2.8V +/- 0.1V.