Panasonic CT-20D12DF-1, Руководство по обслуживанию

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Service notes (continued)
IMPORTANT: To protect against possible damage to
the solid state devices due to arcing or static discharge,
make certain that all ground wires and CTR DAG wire
are securely connected.
CAUTION: The power supply circuit is above earth
ground and the chassis cannot be polarized. Use an
isolation transformer when servicing the receiver to
avoid damage to the test equipment or to the chassis.
Connect the test equipment to the proper ground ( ) or
(
) when servicing, or incorrect voltages will be
measured.
WARNING: This receiver has been designed to meet
or exceed applicable safety and x-ray radiation
protection as specified by government agencies and
independent testing laboratories.
To maintain original product safety design standards
relative to x-ray radiation and shock and fire hazard,
parts indicated with the symbol on the schematic
must be replaced with identical parts. Order parts from
the manufacturer’s parts center using the parts
numbers shown in this service manual, or provide the
chassis number and the part reference number.
For optimum performance and reliability, all other parts
should
be replaced with components of
identical specification.
X-ray protection circuit check
This test must be performed as final check before the
receiver is returned to the customer. If voltage is out of
tolerance, immediate service and correction is required
to insure safe operation and to prevent the possibility of
premature component failure.
Equipment needed to check the protection circuit:
1. Isolator transformer.
2. High voltage meter.
3. Short jumper.
4. Diode connection jumper.
Use similar diode than D823, refer to parts list for
part No., (diode should support at least 150V.)
Procedure:
1. Connect receiver to isolator transformer.
2. Apply a monoscope pattern.
3. In service mode. (Refer to service mode section)
select register C0B.
4. Measure TP5 (TPs port close to tuner). Compare
the measure of TP5 and set the data for C0B
according the following table
5. Exit service mode and turn receiver OFF.
6. Connect a jumper from TPD16 to TPD17.
7. Connect the diode jumper , cathode to TPD14
(cold GND), anode to TPD15 (hot GND).
Note: Refer to Fig. 2 for test point location.
8. Apply 75V AC to the AC input of the Insulator
transformer.Turn receiver ON.
9. Set PICTURE and BRIGTHNESS to minimum.
10. Increase the AC voltage at the input of Insulator
transformer and confirm the HHS voltage is
32.0kV, at the point set starts to loose sync,
11. Reset picture controls to original levels.
12. Turn the set OFF, and remove all jumpers and
connections from chassis.
TP5
MEASURE (V)
DATA TO
C0B (Hex)
0 ~ 0.93 00
0.93 ~ 0.97 01
0.97 ~ 1.01 02
1.01 ~ 1.05 03
1.05 ~ 1.09 04
1.09 ~ 1.13 05
1.13 ~ 1.17 06
1.17 ~ 1.21 07