Sony KV-27EXR25, Technical Service Data

Page: 33 / 42

CONFIRMATION METHOD (HOLD-DOWN
CONFIRMATION) AND READJUSTMENTS
The
following adjustments should always be performed when replac-
ing the following components 4608, 4607, R629, R628,
R627, R559.
Preparation Before Confirmation.
1.
2.
Remove on the G board and connect a variable
resistor about between pin 1 of IC653 and B+
line.
Supply with variable transformer.
Hold-down Operation Confirmation
1. Turn the Power switch on, and receive a white signal.
Adjust ABL current to 1650 with Picture and
Bright controls.
2. Increase B+ line voltage gradually by adjusting the
resistance of
.
Confirm that the MINIMUM voltage is
less than when the raster disappears during
operation of the hold-down circuit.
Note: When the
circuit starts operating, turn the
set off immediately.
3. Turn the Power switch on, and receive a dot pattern. Adjust
ABL current to 150 with Picture and Bright
controls.
4. Increase B+ line voltage gradually by adjusting
that the MINIMUM voltage is less than
when the raster disappears during operation of hold-down
circuit.
Note: When the hold-down circuit starts operating, turn the
set off immediately.
Readjustment
1. If Hold-down Operation Confirmation cannot be satisfied,
readjustment should be performed by altering the resistance
value of
R570 CONFIRMATION METHOD (HOLD-DOWN
CONFIRMATION) AND READJUSTMENTS
The following adjustments should always be performed when replac-
ing the following components IC653, PM501,
4607, D531,
C627, R591, R627, R628, R675, T500
Preparation Before Confirmation.
1. Turn the Power switch on, and receive a white signal. Set
the Picture and Bright controls to Maximum.
SAFETY RELATED ADJUSTMENTS
2. that the voltage at TP-85 is more than when
the set is operating normally with 120VAC supply.
Hold-down Operation Confirmation
Turn the Power switch on, and receive a white screen.
Adjust ABL current to 1650
with Picture and
Bright controls.
2. Gradually apply DC voltage to TP-85, and
that the
voltage is less than when raster disappears during
operation of the hold-down circuit.
Note: When the hold-down circuit starts operating, turn the
set off immediately.
3. Turn the Power switch on, and receive a dot pattern. Adjust
ABL current to 150 with Picture and Bright
controls.
4. Gradually apply DC voltage to TF-85, and confirm that the
voltage is less than when raster disappears during
operation of the hold-down circuit.
Note: When the hold-down circuit starts operating, turn the
set off immediately.
Readjustment
1. If Hold-down Operation Confiition cannot be satisfied,
readjustment should be performed by altering the resistance
value of
B+ VOLTAGE CONFIRMATION
The following adjustment should always be performed when replac-
ing IC653 and R675.
1.
2.
3.
4.
5.
Supply 130VAC with variable auto-transformer.
Receive a monoscope signal.
Set Picture and Bright controls to initial reset position.
that the voltage at TP-91 is less than 137V.
If step 4 cannot be satisfied, replace IC653 and R675.
Repeat above steps.
Courtesy of
Manufacturer