Hitachi C28W40TN, Service Manual

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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