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(6) Adjustments of SCREEN VR(Reference Chan-
nel Decision) and FOCUS VR
i) Connect
the probe
of an oscilloscope
to
TPl(RK) on the CRT SOCKET BOARD and
monitor the waveforms from the end of V.BLK
to start of pictures at a V rate.
ii) Next, adjust the SCREEN VR until the top of
bias pulse reaches l00V DC.
iii) Not changing the range of the oscilloscope,
measure the voltages of bias pulse at TP2(GK)
and TP3(BK) on the CRT SOCKET BOARD.
Then, readjust the channel of the intermediate
voltage among the three channels to lO0V DC
with the SCREEN VR in order to decide the
reference channel.
Setting of BIAS PULSE LEVEL
Waveform of TP1
(V rate magnifying waveform)
--------
..- Pedestal line
100VDC
GND --'-----------
- 13 -
iv) Set the BACKGROUND VR of the reference
channel decided in the step iii) to its MAX
position ..
Next, preset the BRIGHTNESS and adjust the
pedestal potential of the reference channel to
105V DC with the PRESET BRIGHTNESS
VR.
Setting of PRESET BRIGHTNESS
• Waveform of TP1
DC105V
DC100V
v)Adjust the BACKGROUND VR set to MAX. in
the above step so that the raster of the reference
channel can be just before cut off on the screen.
In addition, adjust the other channels in the
same way as the reference using the respective
BACKGROUND VRs.
vi) Input the signal of detailed figures and optimize
the FOCUS VR.
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