Table Of Contents - Facit 4431 Service Instruction

2
SCOPE OF THE MANUAL
The information contained in this manual is in-
tended for the maintenance group, other avail-
able documents are:
Facit 4431 Technical Description
Facit 4431 Operator Guide
INT R 0 DUCT I 0 N _ _ _ _ _ _ _ _
As with any electronic equipment, all standard
safety precautions should be observed while
servicing the Facit 4431 Video Terminal. Any
servicing which requires opening the cabinet
must be performed only by qualified service
personnel.
***********************************************
WARNING
Hazardous voltages are exposed when the cabinet
top is removed. Use extreme caution when servi-
cing the monitor assembly or power supply. Un-
der certain conditions dangerous potentials may
exist even when the power is off due to the
cathode ray tube.
***********************************************
In the text and on the schematics, locations
are referenced in the following manner:
Part number (IC number) (:pin number) (Signal
name) (Schematic page).
Example:
Reference to Pin 19 of D71 located at page MEM
Circuit Diagram: D71:19 RD ATT.(MEM)
Acronyms and Abbreviations:
Main Logic Board Schematic Drawings:
IJO
Input/output interface
KBD Keyboard interface
MEM Display Refresh RAM
CPU Processor
SG Sync Generator
VG Video Generator
Devices:
CPU
CRT
CRTC
EAR OM
EPROM
LED
RAM
ROM
SIO/DART
Central Processing Unit
Cathode Ray Tube
CRT Controller
Electrically Alterable Read-Only
Memory
Eraseable Programmable Read-Only
Memory
Light Emitting Diode
Random Access Memory
Read Only Memory
Serial Input/ output or Dual channel
Asynchronous Receiver/Transmitter
1 . 1
DESIGN
The terminal consists of three major physical
subassemblies:
the Main Logic Board (MLB)
the Keyboard (KBD)
the Monitor assembly
and the Power Supply (PS)
The majority of servicable components are on
the Main Logic Board, which provides six (6)
major circuit functions:
1. Keyboard Interface
2. Microprocessor Control
3. Input/Output Interfaces
4. Display Refresh Memory
5. Synchronization Generator
6. Video Generator
Chapter 6 contains a general circuit descrip-
tion and each of these circuits are described
in detail in Section 7 of this manual. A block
diagram showing the main functional components
of the terminal is given in Fig 7.1. The rest
of Section 7 describes how these components
combine to perform all terminal operations.
1.2 SPECIFICATIONS
Monitor
Screen capacity
Characters per line
Number of lines
Screen
Tube size
Veiwing area
Character size
Referesh rate
Scan method
Character generator
Frequency
Interface
CCITT V24/RS-232-C
Current Loop (Optional)
1920/3168 characters
80/132
25(24 + status
line)
Green phosphor, P42 C
Non glare with medium
short percistance
(300uS)
30.5 cm (12") diago-
nal
310 sq. cm (48
sq.in.)
20 cm x 15 cm (8"x6")
rectangele (centered
on screen) +/-0,2"
(80col) 5mm high x 2
mm wide(0.2"x0.08")
(132col) 5mm high x
2mm wide (0.2"x0.05")
50 or 60Hz
Raster
128 displayable char.
(inc. space) Alterna-
tiv set possible 7 x
9 character defini-
tion with 2 dot sepa-
ration between cha-
racters.
15 700Hz +/- 500Hz
Composite video output (Optional)