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KV-24FV12/25FV12/25FV12A/25FV12C
SECTION 4
SAFETY RELATED ADJUSTMENTS
4-1.
R564 CONFIRMATION METHOD
(HV HOLD-DOWN CONFIRMATION) AND
READJUSTMENTS
The following adjustments should always be performed when
replacing the following components which are marked with on
the schematic diagram:
Preparation Before Confirmation
1. Using a Variac, apply AC input voltage: 120-220 ± 2 VAC.
2. Turn the POWER switch ON.
3. Input a white signal and set the PICTURE and
BRIGHTNESS controls to maximum.
4. Confirm that the voltage between C546 (+) or TP503
and ground is more than 97 VDC.
Hold-Down Operation Confirmation
1. Connect the current meter between Pin 11 of the FBT
(T505) and the PWB land where Pin 11 would normally
attach. (See Figure 1 on the next page.)
2. Input a dot signal and set PICTURE and BRIGHTNESS
to minimum: IABL = 100 ± 100
µ
A.
3. Confirm the voltage of A Board TP-600 is 135 ± 1 VDC.
4. Connect the digital voltmeter and the DC power supply
via diode 1SS119 to C546 (+) and ground. (See Figure 1
on the next page.)
5. Increase the DC power voltage gradually until the picture
blanks out.
6. Turn DC power source off immediately.
7. Read the digital voltmeter indication
(standard < 138 ± 0.3 VDC).
8. Input a white signal and set PICTURE and BRIGHTNESS to
maximum: IABL = 1650 ± 100
µ
A.
9. Repeat steps 4 to 7.
Hold-Down Readjustment
If the setting indicated in step 2 of Hold-Down Operation
Confirmation cannot be met, readjustment should be performed by
altering the resistance value of R564 component marked with .
+
IABL
ABL
T505
FBT
range
-
ammeter
3.0 mA DC
A
4-2. B+ VOLTAGE CONFIRMATION AND
ADJUSTMENT
Note: The following adjustments should always be performed
when replacing the following components, which are marked with
on the schematic diagram on the A Board.
A BOARD:
IC601, PH601
1. Using a Variac, apply AC input voltage: 130 ± 2 VAC.
2. Input a dot signal.
3. Set the PICTURE and BRIGHTNESS controls to minimum.
4. Confirm that the voltage of A Board TP-600 is <136 VDC.
5. If step 4 is not satisfied, replace the components listed above,
then repeat steps 1–3.
Part Replaced ( )
Adjustment ( )
DY, T505, CRT, IC501, C507, C520,
C505, C509, C515, T504, T503,
C551, L510, C546, C537,C547,
D517, D518, D519, R560, R561,
R562, R563, R565, R566, R567,
R525 .................................. A B
oard
IC1301 .............................
MB Board
HV HOLD-DOWN
R564
