Gray Bar Test 3 - Atari CX 5200 Field Service Manual

GRAY BAR
TEST
•
Purpose:
To
test
the functioning
of
the
luminescence
lines
(LM1,
LM2,
LM3)
from
the
GTIA
chip.
•
Procedure: Press key
3
followed by
START.
•
Format:
Eight horizontal gray bars are displayed, going
from
black at the
top
to
white at the
bottom
in
even
steps
(see
Figure 3A-2).
The
screen
should be steady and
unchanging.
These
lines
may have
minor
glitches
on
their edges.
A
thin
white
line
always appears
just
over the top
(black)
bar.
No
color should
appear
anywhere on
the screen.
The
areas
above
the
top
(black)
bar and below
the
bottom
(white) bar are
of
no
importance
to
the
test.
This test should
be
left
on
for at least
ten seconds
to
ensure
that there
is
no flashing of
any
color or shifting of
the gray
bars.
Diagnostic
Flowchart Entry
Point: Pg. 4A-16.
Figure 3A-2. Gray
Bar
Screen
CX5200
Field Service
Manual 3A-5 Changed by
ECN
#0036
6/21/83