Section 3: Safety Related Adjustments; R530, R531 Confi Rmation Method (Hv Hold-Down Confi Rmation) And Readjustments; B+ Voltage Confi Rmation And Adjustment - Sony TRINITRON KV-27FS320 Service Manual

3-1. X R530, R531 CONFIRMATION METHOD
(HV HOLD-DOWN CONFIRMATION) AND
READJUSTMENTS
The following adjustments should always be performed when replacing
the following components which are marked with Y on the schematic
diagram:
Part Replaced (Y)
C531, C532, D519, D520,
D521, IC501, IC600, PH602,
R529, R530, R531, R532,
R533, R550, T503 (FBT),
T504 (DFT)
PREPARATION BEFORE CONFIRMATION
1. Using a Variac, apply AC input voltage: 120 +/- 2.0 VAC.
2. Turn the POWER switch ON.
3. Input a white signal and set the PICTURE and BRIGHT controls to
maximum.
4. Confi rm that the voltage of more than 23.0 VDC appears between
TP85 and ground on the A Board.
HOLD-DOWN OPERATION CONFIRMATION
1. Connect the current meter between Pin 11 of the FBT (T503) and the
PWB land where Pin 11 would normally attach. (See Figure 1).
2. Input a dot signal and set PICTURE and BRIGHTNESS to minimum:
IABL = 2175 + 100/ -325 µA.
3. Confi rm the voltage of A Board TP91 is 134.6 ± 1.0 VDC.
4. Connect the digital voltmeter and the DC power supply to TP85 and
ground. (See Figure 1).
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:
KV-27FS320 Only (standard = 24.78 + 0.0/ - 0.1 VDC).
All except KV-27FS320 (standard = 27.24 + 0.0/ - 0.1 VDC).
8. Input a white signal and set PICTURE and BRIGHTNESS to
maximum: IABL = 2175 + 100/ -325 µA.
9. Repeat steps 4 to 7.
KV-27FS320/32FS120/32FS320/34FS120/36FS120/36FS320/38FS120

SECTION 3: SAFETY RELATED ADJUSTMENTS

Adjustment (X)
HV HOLD-DOWN
R530, R531
KV-27FS320/32FS120/32FS320/34FS120/36FS120/36FS320/38FS120
HOLD-DOWN READJUSTMENT
If the setting indicated in Step 2 of Hold-Down Operation Confi rmation
cannot be met, readjustment should be performed by altering the
resistance value of R530, R531 component marked with X.
digital multimeter
R531 R530
DC Power Supply
3-2. B+ VOLTAGE CONFIRMATION AND
ADJUSTMENT
Always perform the following adjustments when replacing the following
components, which are marked with Y on the schematic diagram on the
A Board:
Adjustment (Y)
A BOARD
IC600, PH602
1. Using a Variac, apply AC input voltage: 130 + 2.0/-0.0 VAC
2. Input a monoscope signal.
3. Set the PICTURE control and the BRIGHT control to
minimum.
4. Confi rm the voltage on A Board between TP23 and ground is less
than 136.5 VDC.
5. If step 4 is not satisfi ed, replace R530 and R531 on A Board and
repeat the above steps.
+
-
T503
TP85
TP85
FBT FBT
ammeter
3mA DC range
+
-
A
+
-
Figure 1
27