Panasonic BT-M1950Y Service Manual page 32

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•How TO CHECK THE HIGH VOLTAGE HOLD CIRCUIT
1. HIGH VOLTAGE HOLD DOWN CIRCUIT
After repairing of the high voltage hold down circuit shown
in Fig. 1.
This circuit shall be checked to operate correctly.
IC501
X-RAY
PROTECT
D701 R714
+
C701 R715
FR704
D702
HEATER-------------~
T701 HVT
1---1
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SIGNAL PB
Fig.1
2. CHECKING OF THE HIGH VOLTAGE HOLD DOWN
CIRCUIT
1) Make sure that power switch is at OFF position.
2) Connect the High Voltage Meter to the CRT Anode.
3) Input the NTSC crosshatch pattern.
4) Turn the power switch ON.
5) Turn Brightness and Contrast controls to the minimum.
6) Turn the power switch OFF.
7) Remove the G connector in the Deflection PB and
connect the self-making service equipment
#2.
8) Connect the self-making service equipment #1 to the
G1 connector than turn the power switch of the monitor
ON.
Be sure that the switch of the equipment must be OFF
position.
9) Set the DC power supply 85V then turn the equipment
switch ON.
10) Gradually increase the DC voltage from 85V. Confirm
the High Voltage will disappear at the voltage between
27.0-29.0kV. After confirming, turn the power switch
of the monitor OFF.
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11) Turn the service equipment #1 switch OFF then dis-
connect the equipment from the G1 connector.
12) Disconnect the service equipment #2 from the G
connector then put the G connector back the original
condition.
DIODE
DC POWER
SUPPLY
SWITCH
Service equipment #1
TO G1 CONNECTOR
~-----l6
330Q
6W
330Q
6W
5
4
3
2
1
Service equipment #2
Fig. 2
*Notice
• While checking, sometimes the picture may roll vertically
or the picture may be back. It is no effect to check this
circuit.
• Self-making service equipments.
• Service equipment #1 :
The DC power supply requires to have over 1 A DC
current.
Use the diode RG4C/RU30/RU3AM/RU4AM or the
same type.
• Service equipment #2:
The total resistance must be 660'1.
The total reted power (W; wattage) must be over 12W.