Safety Related Adjustments - Sony TRINITRON KV-27EXR20 Service Manual

KV-27EXR20/27EXR25 |
RM-Y103__ RM-Y104
SECTION 4
SAFETY RELATED ADJUSTMENTS
Note: Test Equipment Required. 3. Hold-down readjustment
1. Ammeter When step 2 is not satisfied, readjustment should
2. DC Power Supply
3. Digital multimeter
4, Audio OSC
be performed by altering the resistance value of
R559 (a component marked with 54). F
TS00
: FeT |
5. Valiable auto-transformer |
ammeter
A BOARD AND G BOARD
Ba 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).
PM501,Q608,Q607,R629,R628,R627,R559
(1]
1. Preparation before confirmation
1) Remove R675 on the G board and connect a
variable resistor (RV1: about 10k2 ) between
pin @ 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 input an
entirely white signals and adjust ABL current to
1650 +80 yA with PICTURE and BRIGHT etc
controls.
2) Increase B+ line voltage gradually by adjusting
the resistor of RV1. Confirm that the minimum
voltage is less than 143.5V 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 input a dot
signals and adjust ABL current to 150+50pA
with PICTURE and BRIGHT etc controls.
4) Increase B+ line voltage gradually by adjusting
the resistor of RV1. Confirm that the minimum
voltage is less than 146.5V 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.