Atari 400 Field Service Manual

400 POWER-UP
CATASTROPHIC
FAILURES
AND
BASIC
OPERATIONS
BLACK/GREY
SCREEN
Is the
screen
black
or gray
lYES
NO
Check Power
Supply
Board
for:
Is there -5v
on J201
Pin 18
iGo
to
GREEN/YELLO
I
SCREEN,
Page
5-^
NO
YES
Check,
repair,
or
replace the
following:
CR206
-
CR209
-
replace 1N400I
type
diodes
with
1N5391
(C017988)
CR201
-
Ca203,
and
C2ai, C202.
and
C210
Is
there
>I2v an
J201. Pin
2
NOTE
1
See Table
5-1,
start
at the
top of it
and
trace
back
until clock
signal
appears,
indicating
which
component
has failed.
/
/
NO
YES
Check . repair
, or
replace the following;
Voltage
Regulator
(A20I),
CR204
and
C203
-
C205
Check
the CPU
Board for:
''
Clock Circuit
(see
NOTE
I)
Chip Reset
Voltages:
NO
Is there +5v
on
A302,
Pin 36 and
A303,
Pin 30
Repair
YES
Replace CTIA/GTIA
(A301)
Is a
clear
MEMO
PAD
on- the
screen
YES
Go
to
POWER-UF.
PART
II.
Page
5-8
NO
Go
to
C,
next page
ATARI
Home
Computer
5-4

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)