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C
1
VIDEO MAP
PAGE
2 OF
4
l07
.Switch power OFF
~.
-Exchange the video card.
GO TO MAP
0000,
ENTRY POINT BB.
ooa
-Release Intensity
Override~
(ENTRY POINT CCl
-See Figure 6-7 and Figure 6-9.
-Meter the 3 video card grid test points
shown below.
Use the -150 V de meter
range.
Use a ground braid or the
brightness potentiometer plate as ground.
-With the brightness control set to
MINIMUM, the voltages on the test points
should be between
-50 V
dc and
-80 V
dc.
.With the control set to MAXIMUM, the test
point voltages should be between -20 V de
and
-60 V
dc.
GREEN GRID Test Point
=
GG
BLUE GRID Test Point
=
BG
RED GRID Test Point
=
RG
Do the
3
grid voltages look good?
Y N
009
Is only the blue grid voltage bad?
Y N
D E
010
(ENTRY POINT DOl
-Adjust the settings of the brightness
limiting (color balance)
potentiometers on the amplifier card
of the bad color.
See Figure 1-4.
can the bad grid voltage be corrected?
Y N
011
-See Figure 6-7 and Figure 1-4.
-Switch power OFF
~.
-Check the continuity of the PI5
connector on the video card to the
amplifier card connectors PI7A and
Pl7B.
·If
the continuity
is
good exchange
the amplifier card.
Has the problem gone?
Y N
012
·Exchange the video card, then the
CRT.
GO TO MAP
0000,
ENTRY POINT BB.
013
GO TO MAP
0000,
ENTRY POINT BB.
14
-Set up the color balance.
See MIM
section 5.3.6.
-Check for a possible intermittent
problem.
GO TO MAP
0000.
ENTRY POINT BB.
A 0 E
1
MAP 0300-2
L
IS the blue grid voltage constant (and
between -10 V and -20
v
de)
as
the
brightness control is turned?
Y
I
i6
6
TO STEP
010.
ENTRY POINT DO.
017
GO TO MAP
0800,
ENTRY POINT DO.
018
.Switch power OFF
~.
-Exchange the video card.
.If the problem remains exchange the
CRT.
GO TO MAP
0000,
ENTRY POINT BB.
019
-Release Intensity Override.
Turn up tl,e brightness.
Is the problem that
ALL 3
rasters are
permanently on (as if IntenSity Override
is always active)?
Y N
020
Is the problem that ONE RASTER is
permanently on?
(that is, there is a solid RED, GREEN.
or BLUE raster which may be dim or
bright).
Some characters may
be
just
visible.
Y N
021
.Set the TEST/NORMAL switch to TEST.
-Look at the normal cursor -
it
should
be WHITE - that is,
mada
up of RED
and BLUE and GREEN.
IS the problem that ONE of the
3
primary colors is never displayed on
the screen?
VI
i~2TO
PAGE
4,
STEP
036,
ENTRY POINT BB.
023
-Ground the suspect video signal for a
few seconds, where
it
comes on to the
video card.
GREEN
=
Test Point GI
RED
=
Test Point
RI
BLUE
=
Test Point
81
See Figure 6-9.
Does a full raster appear in the
correct color?
Y N
3 3 3
F G H
024
.Switch power OFF
~.
-Exchange the video card.
.If the problem remains, exchange
the
CRT.
GO TO MAP
0000.
ENTRY POINT
SB.
04FEB8l
MAP 0300-2
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