Atari 400 Field Service Manual

400 ANY
VIDEO
TaoUBLESHQOTING
(contl
Verify
that
each
of the
following
levels
and/or
signal wave
forms exist
before
proceeding
to
the
ne« step.
Use
SAX-T
II,
COLOR
BARS.
locked
into
the
continuous
mode.
Is there
3.58MHz
osciXIation
at R15S
on Mother
boaz4.
Refer
figure
YES
Is there
input
signal
to
base of
gi07 Refer
FLgur«
YES
la
there
output
signal
from
coUectoi
on QIQ7
Refer
Figure
YES
NO
Swap-out
XlOl.
Q103
and
QI04
NO
Trace
circuit
back to
previous
step
NO
Trace
circuit
back
to
previous
step
Is there
signal
at
J107.
Pin
1 Refer
Figure
NO
Trace
circuit
back to
previous
step
YES
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next
page
ATARI
Home
Computer
5-20

Atari 400 Specifications

General

Manufacturer	Atari
Model	400
Type	Home Computer
Release Year	1979
CPU	MOS Technology 6502
CPU Speed	1.79 MHz
ROM	10 KB
Operating System	Atari OS
Keyboard	Membrane keyboard
RAM	8 KB (expandable to 48 KB)
Graphics	ANTIC and GTIA chips
Sound	4 channels
Display	RF output for connection to TV
Storage	Optional cassette tape drive or floppy disk drive
Ports	Cartridge
Display Resolution	320x192 (16 colors)