Hitachi C1421R/T Wartungshandbuch Seite 3

SAFETY PRECAUTIONS
WARNING : The following precautions should be
observed.
—
. Do not install, remove, or handle the picture tube in
any manner unless shatter proof goggles are worn.
People not so equipped should be kept away while pic-
ture tubes are handled. Keep the picture tube away
from the body while handling.
. When service is required, an isolation transformer
should be inserted between the power line and the
receiver before any service is performed on the chas-
sis.
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When replacing the chassis in the cabinet, ensure all
the protective devices are put back in place.
. When service is required, observe the original lead
dressing. Extra precautions should be taken to ensure
correct lead dressing in the high voltage circuit area.
. Always use the manufacturer's replacement compo-
nent. Always replace original spacers and maintain
lead lengths. Especially critical components are indi-
cated as /A\ on the parts list and should not be
replaced by other makes. Furthermore, where a short
circuit has occurred, replace those components that
indicate evidence of overheating.
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. Before returning a serviced receiver 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, and be sure that no protec-
tive device built into the instrument by the manufactur-
er has become defective, or inadvertently damaged
during servicing.
Therefore, the following checks are recommended for the
continued protection of the customers and service techni-
cians.
INSULATION
Insulation resistance should not be less than 10M ohms
at 500V DC between the main poles and any accessible
metal parts.
Also, 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.
HIGH VOLTAGE
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 pro-
duce X-radiation levels moderately in excess of design
levels. The high voltage must not, under any circum-
stances, exceed 29kV on the chassis.
X-RADIATION
TUBES : The primary source of X-radiation in this receiv-
er is the picture tube. The tube utilised for the above
mentioned function in this chassis is specially construct-
ed to limit X-radiation.
For continued X-radiation protection, replace tube with
the same type as the original HITACHI approved type.
PRODUCT SAFETY NOTICE
Many electrical and mechanical parts in HITACHI televi-
sion receivers have special safety related characteristics.
These characteristics are often not evident from visual
inspection nor can the protection afforded by them nec-
essarily be obtained by using replacement components
rated for higher voltage, wattage, etc. Replacement parts
which have these special safety characteristics are iden-
tified by marking with a A\ on the schematics and the
replacement parts list contained in this service manual.
Ths use of a substitute replacement component which
does not have the same safety characteristics as the
HITACHI recommended replacement one, shown in the
parts list of this service manual, may create electrical
shock, fire, X-radiation, or other hazards.
Product Safety is continuously under review, and new
instructions are issued from time to time. For the latest
information, always consult the current HITACHI service
manual. A subscription to, or additional copies of
HITACHI service manuals may be obtained at a nominal
charge from your HITACHI SALES CORPORATION.
CE MARK
Some of these models may contain the CE mark on the
rating plate.
This illustrates that the T.V contains parts that have been
specifically approved to provide electromagnetic compat-
ibility to designated levels.
Therefore, when replacing any part in this T.V., please
use only the correct part itemized in the parts list of this
service manual to ensure this standard is maintained.
Also, take care to replace lead dressing to its original
state, as this can also have a bearing on the electromag-
netic radiation/immunity.
TUBE DISCHARGE
The line output stage can develop voltages in excess of
25kV; if the E.H.T. cap is required to be removed, dis-
charge the anode to chassis via a high value resistor,
prior to its removal from the tube.