SECTION 4
SAFETY RELATED ADJUSTMENTS
Note:
Test Equipment Required.
1. Ammeter
2. DC Power Supply
3. Digital multimeter
4.
Audio OSC
5. Valiable auto-transformer
ABOARDANDCBOARD
R559 CONFIRMATION METHOD (HOLD-DOWN
CONFIRMATION) AND READJUSTMENTS
The following adjustments should always be per-
formed when replacing the following components
(marked with
on the schematic diagram).
A BOARD :
1. Preparation before confirmation
1) Remove R675 on the G board and connect a
variable resistor
: about
between
pin
of IC653 and
line.
2) Supply
AC to with variable auto-
transformer.
2. Hold-down operation confirmation
1) Turn the POWER switch ON, and input an
entirely white signals and adjust ABL current to
1650
with PICTURE and BRIGHT etc
controls.
2) Increase B+ line voltage gradually by adjusting
the resistor of
Confirm that the minimum
voltage is less than
DC whereby the
raster disappears during operation of hold-down
circuit.
NOTE:
When the hold-down circuit starts
operating, switch
the POWER of
the set immediately.
3) Turn the POWER switch ON, and input a dot
signals and adjust ABL current to
with PICTURE and BRIGHT etc controls.
4) Increase B+ line voltage gradually by adjusting
the resistor of
Confirm that the minimum
voltage is less than
DC whereby the
raster disappears during operation of hold-down
circuit.
NOTE:
When the hold-down circuit starts
operating, switch
the POWER of
the set immediately.
3. Hold-down readjustment
When step 2 is not satisfied, readjustment should
be performed by altering the resistance value of
R559 (a component marked with
q
>.
