Commodore C286-LT User manual

rn N
SERVICE MANUAL
C286-LT
OCTOBER, 1990 PN-400400-01
__ 5,
C=z Commodore

Produced
By:
Commodore
International
Spare
Parts
GmbH
Braunschweig,
West
Germany
SERVICE MANUAL
C286-LT
OCTOBER, 1990 PN-400400-01
INTERNATIONAL EDITION
COMMODORE “INTERNATIONAL EDITION?” SERVICE MANUALS CON-
TAIN PART NUMBER INFORMATION WHICH MAY VARY ACCORDING TO
COUNTRY. SOME PARTS MAY NOT BE AVAILABLE IN ALL COUNTTRIES.
Commodore Business Machines, Inc.
1200 Wilson Drive, West Chester, Pennsylvania 19380 U.S.A.
Commodore makes no express or implied warranties with
regard to the information contained herein. The infor-
mation is made available solely on an as is basis, and the
entire risk as to completeness, reliability, and accuracy
is with the user. Commodore shall not be liable for any
damages in connection with the use of the information
contained herein. The listing of any available replacement
part herein does not constitute in any case a recommenda-
tion, warranty or guaranty as to quality or suitability of
such replacement part. Reproduction or use without ex-
press permission, of editorial or pictorial content, in any
matter is prohibited.
This manual contains copyrighted and proprietary information. No part
of this publication may be reproduced, stored in a retrieval system, or
transmitted in any form or by any means, electronic, mechanical, photo-
copying, recording or otherwise, without the prior written permission
of Commodore Electronics Limited.
Copyright © 1990 by Commodore Electronics Limited.
All rights reserved. Printed in U.S.A.

C286-LT SERVICE MANUAL
TABLE OF CONTENTS
SECTION
1
—
SPECIFICATIONS
TECHNICAL
SPECIFICATIONS.
....ueueueesesenenenenennnsnenensnnnnnnnnnenenenenne
sense
nen
1-1
SECTION
2
—
THEORY
OF
OPERATIONS
2.1
MAIN
PCB
BLOCK
DIAGRAM........ccunseneenennunsensnennensnntnnenneeneenteeteereerenn
2-1
2.2
MAIN
SYSTEM
PARTS..........2222enseneensensnnsunennnunnneeennuneenneeneenteeteereeteen
2-2
2.3
SYSTEM
OVERVIEW.
.....ounnnssenseesensensunsunsnnenneneeentennenetneteeteettereeteeeeen
2-4
DD)
19
2
N
Ze
R
2-5
2.5
VGA
SYSTEM
BLOCK
DIAGRAM......uncenseesenennennsuneensenneenseeeeeeeneeereetennenn
2-6
2.6
FLOPPY
DISK
DRIVE
AND
CONTROLLER.
........cuccnneenennsunnnensunseneneneenee
nennen
2-7
2.7
HARD
DISK
DRIVE.
......2eeeneeseneeseesesunsnennunennnnensenenenenneneeneneneeeneneeenen
2-7
2.8
PARALLEL
PRINTER
INTERFACE........ceccecceneeneeneensunsnnennnennneneeneenenee
nenn
2-8
2.9
RS-232C
INTERFACE.........cccceceseeneneeeensnnunsnennenseneuneneeneeneneeneneenneeenen
2-9
2.10
MODEM
UF
SLOT.......22222eseeseseesenseseennenennennenennenneneeneneenennenennenennen
2-10
2.11
C286-LT
MEMORY
MAP.
......uceeesseeeeseesesnenesnnenenneneenenseneeneeseeenseeneeneeen
2-11
2.12
WO
ADDRESS
MAP.
.....cececeeseeeesenenseeensnennensnneesenennensenesnensenenseesenenen
2-12
SECTION
3
—
TROUBLESHOOTING
3.0
TROUBLESHOOTING
SECTION
—
CAUTION.........2ceeeeseeeneeseeeeneeseeeeeeessennenn
3-1
DISASSEMBLY
INSTRUCTIONS
FOR
C286-LT
3.1
KEYBOARD
REMOVAL
INSTRUCTIONS..........2222esseseeseeeeeeeeenseneeneneen
nennen
3-2
3.2
NICAD
BATTERY
PACK
AND
LITHIUM
CELL
REMOVAL
INSTRUCTIONS................
3-3
3.3
HDD
REMOVAL
INSTRUCTIONS........22e@seeseeeeeeseesenenesenneeneenneen
essen
nenn
3-4
3.4
LCD
POWER
UNIT
INVERTER
REMOVAL
INSTRUCTIONS...........22c2sssesseneenenen
3-5
3.5
MAIN
PCB,
POWER
SUPPLY
PCB,
FDD
AND
SPEAKER
REMOVAL
INSTRUCTIONS......
3-6
3.6
MEMORY
PCB
(OPTION)
INSTALLATION.............22cnsenseseeeeeeenesenseensennenenn
3-7
3.7
WIRING
DIAGRAM.......2cneeneeseseneseenesesneeneeseeeensenensensenessensensenennensene
3-8
3.8
TROUBLESHOOTING
ERROR
MESSAGES.
..........2.cessesseeeenseeneeeseneseee
tens
nnne
3-9
3.9
POWER
ON
DIAGNOSTICS.........2.22eeseeeeseeeeeeeeeeneeneneeeeeseneensenneren
nennen
3-10
SECTION
4
—
PARTS
COMMODORE
STOCKED
PARTS.
......ceeesseseeeeeseeeeenennneneeeennssnn
nennen
nnn
seen
4-1
SERVICE
REFERENCE
PARTS
DIAGRAM.
........cecenseeeeeenseeeeeenenesen
sense
nr
nennen
4-2
SECTION
5
—
SCHEMATICS
C286-LT
>.
|||‘ een

SECTION 1
SPECIFICATIONS

C286-LT SERVICE MANUAL
1.1
TECHNICAL
SPECIFICATIONS
C286-LT
MEMORY
RAM on board
VIDEO RAM
ROM
RAM EXPANDABLE
on board
CPU
Type
Clock speed
EXTERNAL STORAGE
Floppy disk drive
Type
Supported disks
Hard disk
Capacity
Type
Access time
Interface
DISPLAY
Dimensions
Type
Video mode
Gray scale
AC ADAPTER
Input
Output power
Input current
Dimensions
Weight
SOFTWARE
Operating System
Language
Utilities
Eagle.com
Switcher.com
Alarm.com
Mdmon.com/mdmoff.com
AT Compatible
1MB:
640
KB
Base
memory,
384
KB
extended/expanded
memory;
con-
figurable
by
user
256
KB
(A000:0000H-13000;FFFH):
32
KB
(frame
buffer
for
LCD)
128
KB
(64
KB
for
system
BIOS,
64
KB
for
VGA
video
BIOS)
Yes; to SM — 2 meg. memory expansion cards optional (maximum of two
cards for a total of 5 meg.)
80C286
12.5 MHz, 8 MHz
3.5-inch double-sided high density
3.5-inch 1.4 MB, 3.5-inch 720 KB
20 MB
2.5-inch, low power consumption type
23 ms mean access time
IDE
197 mm x 149 mm (7%” x 5%") diagonal 247 mm (9% ")
0.27 mm dots size and 0.3 mm dot pitch
1:1 aspect ratio
STN type LCD with CFL backlight lamp
Compatible with VGA
Text: 80 characters x 25 lines or 40 characters x 25 lines
Graphics: 640 x 480
8 shades of gray
Operating voltage — 100 to 240 VAC
Frequency — 50/60 Hz
Adapter mode — 24 W
Charger mode — 45 W
Adapter mode — 0.6 A
Charger mode — 1 A
85Wx205Dx55 Hmm
0.65 Kg
MS-DOS 4.01 with Shell
GW-BASIC
LCD control
LCD control
Indicating low battery
Modem power on/off
1-1

SECTION 2
THEORY OF OPERATIONS
NOTE
PLEASE REFER TO C286-LT OPERATIONS MANUAL
PN-363573-01 FOR ADDITIONAL INFORMATION

2-1
I
OPTION
or
EXT
VO
SNP-100
_-_— _- ..-.,
pn
—-
—-
--_
-.
r---
"-
I
VGA-MONITOR
|
RS-232C
| |
(Analog
I/F)
pn
L-
BOARD ASSY
(LED
PCB)
LITHIUM
(@.6V
x
1900mA)
(for
RTC/CMOS)
SNP-286
(MAIN
PCB)
CPU:
80C286
(12.5MHz/8MHz)
*** MAIN PARTS ***
LCD PANEL (with CFL)
(640 x 480)
E FL12V
BATTERY-PACK
(12V
x
1700mA)
AT
CHIP
SET
(OAK)
OTI-051:
SYSTEM
CONTROL
OTI-052:
/O
CONTROL
OTI-053:
DMA
&
MEMORY
CONTROL
OTI-054:
ADDRESS
BUFF
& RTC
OTI-055:
DATA
BUFF
&
PWR
MANAGE
CFP-24
(INVERTOR
PCB)
2.1
MAIN
PCB
BLOCK
DIAGRAM
SPECIAL CARD SLOT
r-—-—-- - -. .
(TTL
V/F
level)
1 SNP-XXX I
| | (MODEM pcB) | |
I
SR-170
(POWER PCB)
5V/0V/+12V/-12V
—-23V/FL12V
CHARGE/ALMIY/ALM2
ALMCK
ROM: 128KB (16 bit) with VGA-BIOS
SYSRAM: 1MB or 2MB
3.5" FDD X1
(720KB/1.44MB)
FL12V
T
VGA CHIP SET (CIRRUS)
GD-610:
GRAPHIC/ATTRIBUTE
CTRL
GD-620:
SEQUENCER/CRT
CONTROL
AC
Adaptor
VRAM: 256KB/FRAM: 128KB (256Kx4)
INTERNAL CONNECTOR
2.5” HDD X1
(20MB)
K/B Matrix
(Membrane
Type)
2.1
—
MAIN
PCB
BLOCK
DIAGRAM
SPEAKER
EXT MEMORY
| |
t 2MB module |
' 1:
|
2MB module
Total:
max
5MB
(STD:
1MB)
/
4MB
(STD:
2MB)
C286-LT
SERVICE
MANUAL

2.2
MAIN
SYSTEM
PARTS
SYSTEM CONTROL OTI-051
1/0 CONTROL OTI-052
DMA
&
MEMORY
CONTROL
OTI-053
ADDRESS
BUFFER
&
RTC
OTI-054
DATA
BUFFER
&
POWER
MANAGER
OTI-055
SYSTEM CLOCK OTI-051
DMA CHANNEL ASSIGNMENT
Channel 0O- Not used
Channel 1 - Not used
Channel 2- Floppy Disk Controller
Channel 3 - 4 Not used
Channel 5 - 7 Not used
INTERRUPT CONTROL OTI-052
INTERRUPT CONTROLLER CHANNEL ASSIGNMENT
IRQ 0 - Timer Channel 0
IRQ 1- Keyboard Interface Interrupt
IRQ 2 - Not used
IRQ 3 - Com2 Interrupt
IRQ4- Com Interrupt
IRQS5 - Not used
IRQ 6 - Floppy Disk Controller Interrupt
IRQ 7 - Printer Interface Interrupt
IRQ 8 - Real Time Clock
IRQ 9 - Not used
IRQIO - Power Saving Mode
IRQ11 - 13 Not used
IRQ14
-
Hard
Disk
Controller
Interrupt
IRQIS - Not used
BUS
CONTROLLER
OTI
-
051
TIMER/COUNTER
OTI
-
052
TIMER/COUNTER
CHANNEL
ASSIGNMENT
Channel
0
-
System
Timer
for
use
with
MS-DOS
Channel
1
-
Memory
Refresh
Timing
Generator
Channel
2
-
Speaker
Beep
Tone
Generator
KEYBOARD/SENSE
CONTROL
PORT
80C42
OUTLINE
OF
OTI-051
C286-LT SERVICE MANUAL
The
OTI-051
is
a
customized
IC
in
the
Oak
Model
35
chip
set
and
it
is
a
system
control
chip
used
in
IBM
AT
and
Model
30-286
architectures.
Its
main
features
are
described
below.
8 MHz, 10 MHz, 12.5 MHz, 16 MHz and 20 MHz system
speeds supported
8 MHz asynchronous mode, and 8 MHz, 10 MHz and 12
System Control
I/O Channels
MHZ synchronous modes
Programmable wait state
Laptop Power management function
Other Features
Fast reset and time-out counter
2-2

C286-LT SERVICE MANUAL
2.2
MAIN
SYSTEM
PARTS
(Continued)
OUTLINE
OF
OTI-052
The
OTI-052
is
an
/O
peripheral
controller
circuit
which
comes
with
the
following
functions.
e
Two
8259-compatible
interrupt
controllers
e
8254-compatible
timer/counter
e
16450-compatible
serial
communication
controller
e Floppy disk controller, hard disk subsystem, keyboard controller, numerical calculation processor and other chip
select circuits
e Numerical calculation processor interface circuit
OUTLINE OF OTI-053 DMA & MEMORY CONTROLLERS
The OTI-053 is an integrated circuit which has a DMA controller and memory controller, and its main features are
listed below.
© () wait cycle page mode and interleave mode
e DRAMSs with access times ranging from 60ns to 120ns supported
e System speeds up to a maximum 20 MHz
e Programmable wait state for slow-speed DRAMs
e Non-wait state ROM cycle execution enabled with use of shadow RAM
© EMS4.0 supported
e 640KB system memory and total memory space of up to 8MB using extension/expansion memories supported
e 256KB and 1IMB type DRAMSs supported
e Dummy SRAM for laptop models supported
® Cartridge ROMs supported
DMA Control
e Fast and normal DMA modes with built-in 8237 to handle operating speeds up to 10 MHz
Laptop Support
e Power-saving mode
OUTLINE OF OTI-054
The OTI-054 is a customized IC in the Oak Model 35 chip set and it is an address buffer driver for IBM AT, Model
30 and other 286-compatible systems. It features all the TTL address and command driver functions normally re-
quired on a system board. In addition to its address driver functions, it comes with an RTC (real-time clock) function.
Except for the 3 items below, the RTC function is compatible with the MC146818.
®
128-byte
CMOS
RAM
in
total
®
No
CKFS
(clock-out
frequency
select)
input
facility
°
No
SQW
(square
wave)
output
facility
OUTLINE
OF
OTI-055
The OTI-055
features
all the
TTL
data driver
functions
normally
required
on
a system
board
and,
in addition
to its
data
buffer
functions,
it
comes
with
power
manager
functions
for laptop
computers.
It has
16 bidirectional
control/status
signal
lines
which
can
be
used
by system
designers
to
control
power
distribution
to peripheral
units
inside
a
system.
Besides these 16 signal lines, it features an internal timer/counter which enables the user to supply power automatically
to the system.
2-3

2-4
OPTION
(2M)
BMB
SD0-
15
MEMORY
RAS/CAS
OTI-053
Extended/
Expanded
MAI1-10
DMA
and
Memory
n
|
"BASE
MODEL
1
ı
MEMORY
SIZE
1MB
(FUCTORY)
I
OPTION
2M,
2M
|
TOTAL
MEMORY
SIZE
5MB
|
BASE
MODEL
2
|
MEMORY
SIZE
2MB
(FUCTORY)
|
OPTION
2M
| _
TOTAL
MEMORY
SIZE
4MB
0OSC
Controller
SD0-»-15
BIOS
PCAI1-16
SA1»23
80386SX-16
CPU
SA0»23
SD0»15
80386SX-16 |
Co-Processor |
_
(Option)
___1
OTI-051
32/40M
Bus Control
RESET
NMI
VGA
SA0x23
SA0»23
SDO-
15
SD0-15
OTI-054
Address
Buffer
RTC
PCA0-9
WD37C65C
FDC XD0x7
LA1723
PCA0»20
XD0-7
OTI-052
Vo
Personal
Controller
XD0-7
80C42G
Keyboard
Controller
DATA/CLK
XD0»7
LOCAL BUS
OTI-055
Data
Buffer
Power
Mg
PCDO-
15
XD0-7
3.5 inch 2HD
SPEAKER
RS232C
PRINTER
HARD
DISK
(IDE)
80C41
Keyboard
Interface
iss]
16C450
sı0
XD0-7
INTERNAL
1/O
BUS
2.2
—
SYSTEM
OVERVIEW
AT
BUS
GD610/620
VGA/LCD
INTERFACE
VRAM
Size
256Kb
16 Bit Memory
B Bit VO
CPT
LCD
2.3
SYSTEM
OVERVIEW
C286-LT
SERVICE
MANUAL