Sony PFM-42X1 Service Manual page 25

4 Connect the GND probe of DMV to the GND of
the Y B/D, and connect the positive probe to the
lower leg of R44 to check the _Vy voltage (_175
± 1 V). When there is abnormality in the voltage,
turn the variable resistor (PS2) of DC/DC Pack
(_Vy) on Y B/D to adjust it.
5 Connect the GND probe of DVM to the GND of
the Z B/D, and connect the positive probe to the
upper leg of B34 to check the Vzb voltage (_105
± 1 V). When there is abnormality in the voltage
turn the variable resistor (A2) of DC/DC Pack
(_Vzb) on Z B/D to adjust it.
3) Measuring the Vs voltage margin and determining the
voltage
1 Switch the signal of the signal generator to the
100% Full Red signal.
2 Turn the voltage adjusting knob of the Vs DC
power supply in the voltage-down direction, and
turn off the cells of the screen.
3 Turn the voltage adjusting knob of the Vs DC
power supply in the voltage-up direction until the
cells of the screen turn on. The first voltage, which
turns on the cells of the entire screen, is named as
Vsmin1. Record the value of Vsmin.
4 Turn the voltage adjusting knob of the Vs DC
power supply in the voltage-up direction slowly
until the cells of the screen turn off or until over-
electric discharge happens. The first voltage,
which turns off the cells of the screen or causes
over-electric discharge, is named as Vsmax1.
Record the value of Vsmax1. (Note that the Vs
voltage variable should exceed the maximum of
195 V.)
5 Switch the signal of the signal generator to the
100% Full Green signal.
6 Repeat the previous adjustment step (2), and
record each voltage as Vsmin2/Vsmax2.
7 Switch the signal of the signal generator to 100%
Full Blue signal.
8 Repeat the previous adjustment step (2), and
record each voltage as Vsmin3/Vsmax3.
9 Switch the signal of the signal generator to 100%
Full White signal.
0 Repeat the previous adjustment step (2), and
record each voltage as Vsmin4/Vsmax4.
!- Switch the signal of the signal generator to 100%
Full Black signal.
!= Repeat the previous adjustment step (2), and
PFM-42X1/42X1N
record each voltage as Vsmin5/Vsmax5.
![ At this time, the maximum voltage is set by
adding 6 V to the Vs voltage (Vsmin1 to Vsmin5).
Set the voltage within the setting range (180 V <
Vs < 195 V) while considering other characteris-
tics as well.
!] Turn the voltage adjusting knob of the Vs DC
power supply, and determine the Vs voltage.
!\ Adjust the Vset-down waveform by setting the Vs
voltage as described in 2-3-4.
4) Adjusting the final voltage waveform
1 Check the voltage waveform as described in 2-3-4
(3. How to adjust), and readjust the waveform
when it is out of range.
5) DC-DC Pack voltage setup range
V1st : 100V to 160 V
Vsc : 100 V to 160 V
_Vy : _160 V to _200 V
_Vzb : 100 V to 160 V
2-5