High Voltage Hold-Down Check; Beam Current Protector Check - Sony BVM-D14H1E Maintenance Manual

High Voltage Hold-Down Check

When the following parts (the parts to which the
is attached on the schematic diagram) are replaced, be sure
to perform the following checks.
G board ...... IC514, IC507, IC523, Q520, D506,
D513, D535, T502, R553, R560, R561,
R569, R575, R597, R1566, R512
1. Turn off the main power.
2. Connect a digital voltmeter between D513 cathode and
GND of G board.
3. Connect a 200 kΩ variable resistor between IC523
pin-2 and GND of the G board.
[Adjust the 200 kΩ variable resistor to its maximum
resistance value.]
5. Connect the 480/60i entire black signal (see note) to
input connector.
Note: NTSC entire black signal
6. Push the BRIGHTNESS and CONTRAST buttons to
their MANUAL positions (to turn the green LEDs on
the buttons.)
7. Set the BRIGHTNESS and CONTRAST buttons to
their MIN positions.
8. Confirm that the raster disappears from the CRT
screen when the DC voltage at D513 cathode reaches
the following voltage as the 200 kΩ variable resistor is
turned to decrease its resistance value gradually.
25.5 ± 1.0 V
9. Turn off the main power.
10. Remove the 200 kΩ variable resistor that is connected
to IC523 pin-2.
11. Turn on the main power.
12. Confirm that the DC voltage at D513 cathode is as
follows.
20.0 ± 1.5 V
13. Connect the 480/60i entire white signal to input
connector.
14. Set the BRIGHTNESS and CONTRAST buttons to
their MAXIMUM positions.
15. Confirm that the DC voltage at TP505 is as follows.
22.0 ± 2.0 V
16. Disconnect the digital voltmeter.
BVM-D14H1U/D14H5U/D14H1E/D14H5E/D14H1A/D14H5A

Beam Current Protector Check

mark When the following parts (the parts to which the
is attached on the schematic diagram) are replaced, be sure
to perform the following checks.
G board ....... IC507, IC517, IC523, Q520, D507,
1. Turn off the main power.
2. Connect a DC ammeter and a 20 kΩ variable resistor
in series between the junction point of R1522 and
R1523, and GND on the G board
[The junction point of R1522 and R1523 is the
positive (+) side. Adjust the 20 kΩ variable resistor to
its maximum resistance beforehand.]
3. Turn on the main power.
4. Connect the 480/60i entire black signal (see note) to
input connector.
Note: NTSC entire black signal
5. Push the BRIGHTNESS and CONTRAST buttons to
their MANUAL positions (to turn the green LEDs on
the buttons.)
6. Set the BRIGHTNESS and CONTRAST buttons to
their mechanical center positions.
7. Confirm that the raster disappears from the CRT
screen when the DC ammeter reaches the following
value as the 20 kΩ variable resistor is turned to
decrease its resistance value gradually.
1600 µA
8. Turn off the main power.
9. Remove a 20 kΩ variable resistor and a DC ammeter.
D535, T502, R1516, R1517, R1518,
R1521, R1522, R1523, R1566, R1569,
R512, R562, R576, R578, R579, R580,
R586
mark
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