Atari 400 Service Manual

Table 5-1. Troubleshooting Guide
Description Possible failure Test
Procedure
MEMO PAD TEST
• Green Screen
• Black Screen
• Random Characters on
Screen
• Unit Locks Up
• Character begin scrolling
across screen
Loose or dirty
contacts with RAM
or CPU boards
Motherboard
1
2
VISUAL INSPECTION
• Damaged or bent pins
• Cover Closed switch will
not work properly
• RF Cable cut or badly
damaged
• Bare or pinched area on
RF cable
Replace damaged
board
Plunger or Power
Supply
Replace RF Cable
Replace RF Cable
2
2
Replace
immediately
Replace
immediately
KEYBOARD TEST
• Key depressed not
displayed
• Key depressed not same
key that appeaes on
screen
• Characters begin
scrolling across screen
Motherboard
Or
Keyboard
2
STAND ALONE TEST
• System Error (can not
power-up with Stand Alone
Test Cartridge inserted)
• Fails Any Video Test
• Fails Color Bar test
• Fails Gray Bar test
Cartridge Guide
RAM Memory Board
CPU Board
2
2

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)