A Board Adjustment - Sony Trinitron KV-25XBR Service Manual

4-1. A BOARD ADJUSTMENT
SECTION 4
CIRCUIT ADJUSTMENTS
KV-25XBR
RM-724/APM-X3U
KV-25XBR
RM-724/APM-X3U
I
BLACK LEVEL ADJUSTMENT!
(1) Receive color bar signal.
(2) Set the analog level of the microcomputer to the
standard.
(3) Add 6V DC to pin
@
(SUB BRT terminal) of A-16
connector.
(4) Adjust the black level volume (RV406) so as to the
voltage of pin
@
of IC401 (black level terminal)
becomes equal to the black level waveform of Pin
@
of /C401.
Waveform of pin
@
of IC401
(Caution) The black level of pin
@
waveform of
/C401 should be equal to the pedestal level
In addition, the voltage of pin
@
of IC401 should
not be higher than that of the black level.
-19 -
Oscilloscope
DC stabilized
power supply
I
BAR DISPLA y POSITION ADJUSTMENT
I
(1) Receiver the broadcasting signal.
(2) Press the picture button so that the received signal
becomes maximum.
(3) At this point, adjust the undisplayed portions of the
left and right sides of the bar signal so as to become
equal with l102.
Digital mu/ti-meter
II
ll~J
I
ACC ADJUSTMENT AND HUE ADJUSTMENT
I
(1) Receive color bar signal.
(2) HUE ..... 50% (resetting)
COLOR THICKNESS ..... 50% (resetting)
PICTURE ..... Maximum
(3) Observe pin
@
of/C301 with an oscilloscope, and
adjust the output 'waveform so as to become that as
shown in the diagram by turning the ACC volume
(RV304) and Hue volume (RV303).
(])
0 @
2.3±0.8 Vp-p
LJ @
@
Make levels of
Cl)
to
@
even.
@
to
@
have a little residual tilt.)
(4) Confirm that the voltage at the middle point of the
ACC volume (RV304) should be less than 911.
(5) Confirm that the blue output should be 2.3
±
0.2V
after adjusted.
Oscilloscope
~-
oscilloscope
11
ll~;J-----
I
RF AND AGC ADJUSTMENT (ROUGH ADJUSTMENT)
I
(1) Adjust with RV201 (RF AGC) so as to disappear snow
noise and cross-modulation.
(Caution) Measurement should be performed under
the conditions that removing A- 16 connector and not
applying ABL
(2) Confirm them at every channel.
-20
~
Oscilloscope
~
q I
MPX ADJUSTMENT
I
(1) Receive dot signal with channel 9.
(2) Observe pin
CJ)
of A· 7 connector with
(3) Adjust it with the MPX volume (RV