Panasonic tx-34p180b, Service Manual

Page: 15 / 51

5.9. CUT OFF
Preparation
1. Receive a colour bar signal with colour “OFF” and operate
the TV set more than 15 minutes.
2. Set the picture menu to “DYNAMIC NORMAL” and the AI to
off.
3. Connect an oscilloscope to TPL7 with DC mode.
4. Set the TV set to Service Mode 1.
5. Screen VR: Min.
6. Set the data level of SUB BRIGHT, R, G, B-CUTOFF and
R, G, B-DRIVE to the table values.
Display Data Level
R High (R-CUT OFF) 256
G High (G-CUT OFF) 512
B High (B-CUT OFF) 256
R Low (R-DRIVE) 128
G Low (G-DRIVE) 128
B Low (B-DRIVE) 128
SUB BRIGHT 136
Adjustment
1. Select G-CUTOFF adjustment mode and collapse vertical
scan.
2. Adjust G-CUTOFF control to become the DC = 0V to video
level at 180V as shown below.
3. Slowly turn the screen control clockwise until a green colour
horizontal line appears on the picture tube. This is the
setting point for the screen control.
Note that do not adjust the G-CUTOFF setting in the
following procedure.
4. Adjust the remained R and B-CUTOFF controls so as to get
a white horizontal line on the screen.
5. Return to full field SCAN by pushing the position 5 key on
the remote control.
6. Adjust the R-Drive and B-Drive controls as to obtain uniform
white on the white bar of the greyscale pattern.
7. Confirm correct B/W rendition and greyscale tracking or
repeat CUTOFF and drive control setup.
Note :
Write down the original value for each address
adjusment before adjusting anything.
(Fig. 1)
8. Wedge A shown in Fig. 1 should be fixed within a range of
45° to the left of the vertical line as shown.
9. After inserting wedge A, insert wedges B, C and D.
The wedges should be set 90° apart from each other.
10. Be certain that the four wedges are firmly fixed and the
deflection yoke is tightly clamped in place otherwise the
deflection yoke may shift its position and cause a loss of
convergence and purity.
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TX-34P180B