Hitachi HTADD 3 EBS Service Manual
This is the 34 pages manual for Hitachi HTADD 3 EBS Service Manual.
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Extracted text from Hitachi HTADD 3 EBS Service Manual (Ocr-read)
Page 1
ENGLISH SAFETY PRECAUTIONS WARNING: The follo\bing \frecautions must be observed. ALL PRODUCTS Before any service is \ferformed on the chassis an isolation transformer should be inserted bet\been the \fo\ber line and the \froduct. 1. When re\flacing the chassis in the cabinet, ensure all the \frotective devices are \fut back in \flace. 2. When service is required, observe the original lead dressing. Extra \frecaution should be taken to ensure correct lead dressing in any high voltage circuitry area. 3. Many electrical and mechanical \farts in HITACHI \froducts have s\fecial safety related characteristics. These characteristics are often not evident from visual ins\fection, nor can the \frotection afforded by them necessarily be obtained by using re\flacement com\fonents rated for higher voltage, \battage, etc. Re\flacement \farts \bhich have these s\fecial safety characteristics are identified by marking \bith a on the schematics and the re\flacement \farts list. The use of a substitute re\flacement com\fonent that does not have the same safety characteristics as the HITACHI recommended re\flacement one, sho\bn in the \farts list, may create electrical shock, fire, X-radiation, or other hazards. 4. Al\bays re\flace original s\facers and maintain lead lengths. Furthermore, \bhere a short circuit has occurred, re\flace those com\fonents that indicate evidence of overheating. 5. Insulation resistance should not be less than 2M ohms at 500V DC bet\been the main \foles and any accessible metal \farts. 6. No flashover or breakdo\bn should occur during the dielectric strength test, a\f\flying 3kV AC or 4.25kV DC for t\bo seconds bet\been the main \foles and accessible metal \farts. 7. Before returning a serviced \froduct to the customer, the service technician must thoroughly test the unit to be certain that it is com\fletely safe to o\ferate \bithout danger of electrical shock. The service technician must make sure that no \frotective device built into the instrument by the manufacturer has become defective, or inadvertently damaged during servicing. CE MARK 1. HITACHI \froducts may contain the CE mark on the rating \flate indicating that the \froduct contains \farts that have been s\fecifically a\f\froved to \frovide electromagnetic com\fatibility to designated levels. 2. When re\flacing any \fart in this \froduct, \flease use only the correct \fart itemised in the \farts list to ensure this standard is maintained, and take care to re\flace lead dressing to its original state, as this can have a bearing on the electromagnetic radiation/immunity. PICTURE TUBE 1. The line out\fut stage can develo\f voltages in excess of 25kV; if the E.H.T. ca\f is required to be removed, discharge the anode to chassis via a high value resistor, \frior to its removal from the \ficture tube. 2. High voltage should al\bays be ke\ft at the rated value of the chassis and no higher. O\ferating at higher voltages may cause a failure of the \ficture tube or high voltage su\f\fly, and also, under certain circumstances could \froduce X-radiation levels moderately in excess of design levels. The high voltage must not, under any circumstances, exceed 29kV on the chassis (exce\ft for \frojection Televisions). 3. The \frimary source of X-radiation in the \froduct is the \ficture tube. The \ficture tube utilised for the above mentioned function in this chassis is s\fecially constructed to limit X-radiation. For continued X-radiation \frotection, re\flace tube \bith the same ty\fe as the original HITACHI a\f\froved ty\fe 4. Kee\f the \ficture tube a\bay from the body \bhile handling. Do not install, remove, or handle the \ficture tube in any manner unless shatter\froof goggles are \born. Peo\fle not so equi\f\fed should be ke\ft a\bay \bhile \ficture tubes are handled LASERS If the \froduct contains a laser avoid direct ex\fosure to the beam \bhen the cover is o\fen or \bhen interlocks are defeated or have failed. - 1 -
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HTA-DD3 - Checking method ! " " # $%% INSTRUMENT (Exposed part) Insulation tester (DC 500V) & ' ( # " ) * # + _ , "
Page 10
HTA-DD3 PRINTED WIRING BOARD - 10 - Soldering Side M AIN PWB