Gain Adjustment; Cut Off Adjustment - Tatung OMNISCAN SERIES Service Manual

2.7 Gain adjustment
A. Adjust R032(R), R092 (G) , R152(B) so that the
terminals (Pins 1 of P901, POO2, P903) on the
CRT PWB are each set to 47Vp-p not including
the clamp pulse.)
*
Please use the plastic adjusting pole to do the
alignment.
R G B
[§]l
'00'
~
[§]l
~o ,,,.~
l22l
~
0 ""
~ ~
RCI
0
R043
RI19
0
1
Gel
P179
3
1
Bel
R044
RIOS RI04
PWB- 1642 TOP VIEW
VIDEO BOARD
ROB I
Ge'Z
o
RI63
RI64
RI41
002.
o
D£,D£,D£,
. RDI GOI BOI
---------~c!arrp pulse is
]~~~~~-
not
I
nc
I
uded
2.8 Cut-off adjustment
A. Initial setting of the adjustment VRs.
Rl19, R179: CUTOFF 2 VR MID'POINT
R058, Rl18, R178: CUTOFF 1 VA MID'POINT
R722: Brightness VR fully clockwise
SCREEN VA: fully counterclockwise
B. Apply signal 89 (64KHz), crosshatch pattern.
C. Adjust G1 control ROO7 (PWB-1642-3) so that the
voltage on Gl is Vc (See Table).
17" TOSHIBA 17" HITACHI 17" NEC 20" HITACHI
M41KJF26XX12 M41KKL80X-12 M41KMG23XX M48KAY80X01
M41KMK26XX12
Vc
-90V
-60V
-OOV -70V
290.5
~
+
GI
R907
o
PWB-1642
DRIVE BOAPD
D. As SCREEN VR is gradually turned clockwise, a
signal color will appear. Turn the CUTOFF 1 VR
fully counterclockwise for this color.
E. Again, turn SCREEN VR clockwise gradually, a
signal color will appear again. This color is the
reference color for the cut off adjustment. Set
the background color faintly appears with
SCREEN VR. Use this as your reference then
adjust the other two CUTOFF VRs (other than
the reference color) to form a white background.
F. Measure the color temperature
X
and
Y.
NOTE:
X = 281 (+ /- 5)
Y
=
311
(+/-
5)
*
White tracking will be best at dark cut off
adjustment settings. For the best setting,
therefore, perform the cut off adjustment in. as
dark a place as possible.
2.9 . Contrast Tracking 1
A.
Apply signal 89 (64KHz), full white pattern.
B. Initial Settings of Adjustment VRs.
R721:
R722:
R081, R141:
Contrast VR
Brightness VR
GAIN 2 VR
fully clockwise
MID'POINT
MID'POINT
C. Adjust R GAIN 1 VR (R032) and B GAIN 1 VR
(R152).
D. Measure the color temperature
X
and
Y.
X
=
281
(+/-
5)
Y = 311
(+/-
5)
=
2-4
=