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KV·27XBR51/27XBR55
RM·Y106
RM·Y107
SECTION 4
SAFETY RELATED ADJUSTMENTS
B
RS49 CONFIRMATION METHOD (HOLD-DOWN
CONFIRMATION) AND READJUSTMENTS
The following adjustments should always be per·
formed when replacing the following components
(marked with
Ciil
on the schematic diagram).
IC301, PM501, R549, R564
<D
1. Preparation before confirmation
1) Remove R663 on the F board and connect a
variable resistor (RVl:
about 4.7kJ?-10kn)
between pin
<D
of IC653 and B+ line.
2) Supply 120±2.0V AC to with variable auto-
transformer.
2. Hold-down operation confirmation
1) Turn the POWER switch ON, and receive entire-
ly white signals and adjust ABL current to 1620
±50µA with PICTURE and BRIGHT etc controls.
2) Increase B+ line voltage gradually by adjusting
the resistor of RV!. Confirm that the minimum
voltage is less than 142.5V DC whereby the
raster disappears during operation of hold-down
circuit.
NOTE :
When the hold-down circuit starts
operating, switch OFF the POWER of
the set immediately.
3) Turn the POWER switch ON, and receive dot
signals and adjust ABL current to 150±20µA
with PICTURE and BRIGHT etc controls.
4} Increase B+ line voltage gradually by adjusting
the resistor of RV!. Confirm that the minimum
voltage is less than 145.0V DC whereby the
raster disappears during operation of hold-down
circuit.
NOTE:
When the hold-down circuit starts
operating, switch OFF 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
R549 (a component marked with
8).
PMS01
pin@
ammeter
3.0 mA de
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B
RS67 CONFIRMATION METHOD (HOLD-DOWN
CONFIRMATION} AND READJUSTMENTS
The following adjustments should always be per-
formed when replacing the following components
(marked with
Ciil
on the schematic diagram).
IC301, IC653, PM501, D539, C556, R556, R564, R567,
R663, T500
<2\.
Preparation before confirmation
1) Turn the POWER switch ON, and receive entire-
ly white signals and set the PICTURE and
BRIGHT controls to maximum.
2) Confirm that voltage of the check terminal of pin
®
of F-5 (F BOARD) is more than 127.0V DC
when the set is operating normally with 120.0 ±
2.0V AC supply.
2. Hold-down operation confirmation
1} Turn the POWER switch ON, and receive entire-
ly white signals and adjust ABL current to 1620
±50µA with PICTURE and BRIGHT etc controls.
2) Apply DC voltage of over 140.0V DC gradually
to the check terminal of pin
®
of F-5 (F
BOARD) via 1 T40 from the DC stabilized power
source.
Confirm that the minimum voltage is less than
145.0V DC whereby the raster disappears during
operation of hold-down circuit.
NOTE :
When the hold-down circuit starts
operating, switch OFF the POWER of
the set immediately.
3) Turn the POWER switch ON, and receive dot
signals and adjust ABL current to 150±20µA
with PICTURE and BRIGHT etc controls.
4} Apply DC voltage of over 140.0V gradually to
the check terminal of pin
®
of F-5 (F BOARD)
via 1 T40 from the DC stabilized power source.
Confirm that the minimum voltage is less than
145.0V DC whereby the raster disappears during
operation of hold-down circuit.
NOTE :
When the hold-down circuit starts
operating, switch OFF 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
R567 (a component marked with 8).
-30-
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