Hitachi HTA-DD1E Service Manual Download

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ENGLISH

SAFETY PRECAUTIONS

WARNING:

The following precautions must be observed.

ALL PRODUCTS

Before any service is performed on the chassis an
isolation transformer should be inserted between the
power line and the product.

1. When replacing the chassis in the cabinet, ensure

all the protective devices are put back in place.

2. 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.

3. 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.

4. Always replace original spacers and maintain lead

lengths. Furthermore, where a short circuit has
occurred, replace those components that indicate
evidence of overheating.

5. Insulation resistance should not be less than 2M

ohms at 500V DC between the main poles and
any accessible metal parts.

6. 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.

7. 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,

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

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.