Epson PC AX User manual

EPSON pe AX
TECHNICAL MANUAL
Seiko Epson Corporation
Nagano,Japan
Y12699900201

Fce eOMPLIANCE STATEMENT
This equlpment uses and generates radio trequency energy and It not installed and used properly.
that
Is In strlct accordance wlth the manutacture's Instructlons, may cause Interference to radio
and television receptlon.
It
has been type tested and tound to comply wlth limits tor aClass Bcomputlng devlce In
accordance wlth Sub- part J of Part 15 of FCC Rules, whlch are designed to provlde reasonable
protectlon agalnst such Interference
in aresldential installation. However, there Is no guarantee
that Interference will not occur
In apartlcular Installation. It thls equlpment dose causa
Interference to radio or television receptlon,
wh Ich can be determlned by turnlng the equlpment
on
and off, the user Is encouraged to try to correct the interference by one or more of the
tollowing measures:
reorlent the receivlng antenna
relocate the computer wlth respect to the receiver
move .the computer away tram the receiver
plug the computer into adifferent outtet so that the computer and receiver
are on
different branch clrcults
It necessary, the user should consult the dealer or an experienced radio/television technician tor
additional suggestions.
The user may tind the tollowing booklet, prepared by the Federal
Communicatlons Commlssion, helptul:
"How to Identity and
Resoive Radio - TV interference Problems. ''This booklet Is avaiiable trom
the
U.S. Government Printlng Office. Washington. D.C., 20402, Stock No. 044 - 000 - 00345 - 4.
You can determine whether your computer Is causing interference by turning It off. It the
Interference stops, it was probably caused by the computer or Its perlpheral devlces. To further
lsolate the problem. disconnect elther the perlpheral device or its
1/0 cable.
These devices usually require shielded cable. For Epson peripheral devices, you can obtaln the
proper shlelded cable trom your dealer. For non -Epson devlces. contact the manufacturer or
dealer tor asslstance.
Seiko Epson Corporatlon, Nagano, Japan
© 1988 by Seiko Epson Corporation
All r1ghts reserved.
Prlnted
In Japan
No portion
of thls document may be reproduced, stored In aretrleval system, or transmitted In
any torm or by any means, electrlc. mechanlcal, photocopylng. recordlng, or otherwlse, wlthout
the written permission of Selko Epson Corporatlon. No patent liablllty
Is assumed wlth respect
to use of the Information contalned herein, nor Is any liablllty assumed tor damages resultlng
trom usa
cf thls text. Whlle every precautlon has been taken In the preparatlon cf thls bock,
the publlsher assumes no lIablllty tor errors or omisslons.
EPSON ® is areglstered trademark of Seiko Epson Corporatlon.
EPSON PC AX ™ Is trademark of Selko Epson Corporatlon.
IBM ®is areglstered trademark ot International Business Machlnes Corporation.

PRECAUTIONS
Precautlonary notations throughout the text are categorlzed relative to 1) personalinjury and 2)
darnage to equlpment.
DANG ER
WARNING
Signals aprecautlon whlch, If ignored, could result In serlous or fatal
personalinjury. Great caution should
be exercised in performlng procedures
preceded by
DANGER Headlngs.
Signals aprecaution whlch,
If ignored, could result In damage to equlpment.
The precautlonary measures Itemlzed below should always be observed when performlng repalr/
rnalntenance procedures.
DANGER
1. ALWAYS DISCONNECT THE PRODUCT FROM BOTH THE POWER
SOURCE AND PERIPHERAL DEVICES PERFORMING ANY
MAINTENANCE OR REPAIR PROCEDURE.
2. NO WORD SHOULD BE PERFORMED ON THE UNIT BY PERSONS
UNFAMILIAR WITH BASIC SAFETY MEASURES AS DICTATED
FOR ALL ELECTRONICS TECHNICIANS IN THEIR L1NE OF WORK.
3. WHEN PERFORMING TESTING AS DICTATED WITHIN THIS
MANUAL, 00 NOT CONNECT THE UNIT TO APOWER SOURCE
UNTIL INSTRUCTED TO 00 SO. WHEN THE POWER SUPPL Y
CABLE MUST BE CONNECTED, USE EXTREME CAUTION IN
WORKING ON POWER SUPPL Y AND OTHER ELECTRONIC COM-
PONENTS.
WARNING
1. Repalrs on Epson product should be performed only by an Epsan
certlfled repair techniclan.
2. Make certeln that the source voltage is the same as the rated
voltage, Iisted on the serial number/rating plate. If the Epson
product
has aprimary AC rating different from avallable power
saurce,
do not connect It to the power source.
3. Always verlfy that the Epson product has been disconnected from
the power source before removlng or replaclng prlnted circult
boards and/or Individual chips.
4. In order to protect sensitive microprocessors and clrcultry, use
static discharge equlpment, such as antl- static wrist straps, when
accesslng Internal components.
5. Replace rnalfunctlonlng components only wlth those components by
the manufacture; introductlon of second -source
ICs or other non-
approved components may damage the product and vold any
applicable Epson warranty.

REVISION ISSUE
DATE
REVISION PAGE
REV.A
December
1986
-
REV.B
September
1988
1-7, 2-2, 2-6, 2-7, 2-10,
2-15, 2-25, 2-33, 2-36,
2-39, 2-40, 2-42, 2-51,
2-73
Chapter 8
added

PREFACE
Thls manual descrlbes the theory of operation of the EPSON PC AX microcomputer system, and
Includes troubleshootlng, repair, and malntenance procedures for servlng system subassemblles.
Thls text Is dlvlded into eight chapters:
CHAPTER 1.
CHAPTER 2.
CHAPTER 3.
CHAPTER 4.
CHAPTER 5.
CHAPTER 6.
CHAPTER
7.
CHAPTER 8.
PRODUCT DESCRIPTION
... Descrlbesthe features and speclflcatlons of
the computer, lIIustrates system components.
and IIsts the loglc conflguratlon
of
the prlmary clrcult board.
PRINCIPLES OF OPERATION. "Details the functional organizatlon cfthe
loglc clrcultry.
Thls chapter also Illustrates the gate array pln
configuratlons.
OPTIONS . " Descrlbes option card speciflcatlons and the operating prln-
cl pies of the options.
TROUBLESHOOTING ." ProvIdes Instructions for isolating computer mal-
functlons.
DISASSEMBLYAND ASSEMBLY . .. Descrlbes system dlsassembly for
re placement of malfunctlonlng subassemblles.
ADJUSTMENTAND MAINTENANCE ... Usts the necessaryadjustments for
unlt assembly
and servlclng.
DIAGRAMSAND REFERENCE MATERIALS ... Descrlbes jumper settings
and connector pln asslgnments. Thls chapter also provldes expIoded clrcult
board layout
and schematlc dIagrams for use In conjunctlon wIth the text.
DIFFERENCES BETWEEN 1OMHz AND 12 MHz ... Descrlbes between the
EPSON PC AX 10MHz and the 12MHz, and includes the schematics for use In
conJunctlon with the the 12MHz.
SUbsequent product modlflcatlons will be brought to your attention via Service Bulletins; please revlse
the text as bulletins are recelved.
Thls document Is subJect to change without notice.

TABLE OF CONTENTS
CHAPTER 1. PRODUCT DESCRIPTION. . . . . . . . . . . . . . . 1- 1
CHAPTER 2. PRINCIPLES OF OPERATION 2-1
CHAPTER 3. OPTIONS........................ 3- 1
CHAPTER 4. TROUBLESHOOTING................. 4- 1
CHAPTER 5. DISSEMBLY AND ASSEMBLY 5-1
CHAPTER 6. ADJUSTMENT AND MAINTENACE . . . . . . . . . 6- 1
CHAPTER 7. DIAGRAMS AND REFERENCE MATERIALS .... 7- 1
CHAPTER 8. DIFFERENCES BETWEEN 10MHz AND 12MHz .. 8-1

Section
1.1
1.2
1. 2.1
1.2.2
1.2.3
1.2.4
1.2.5
1.2.6
1.3
1.3.1
1.3.2
CHAPTER
1
PRODOCT DESCRIPTION
TAßLE OF CONTENTS
Title Page
FEATU RES ......••.......••........••.........•............ 1-1
SPEC I FICATIONS ..........................•.•.............. 1-3
t1ain System Unit
Specifications .••......•...•......•... 1-4
Keyboard
Specifications •..........••••.•.....•......... 1-4
FD1155C Floppy Disk Drive Specifications .... .... .••.... 1-4
t1D5501-61 Floppy Disk Drive Specifications ....•.•...... 1-5
D5146H Hard Disk Drive Specifications ..•........ .••. ... 1-6
Hr,1D-720 Hard Disk Drive Specifications .•.•.•.... ..•.... 1-7
HARDWARE CONFIGURATION ............•...................... 1-8
Main System Unit Components ..........•...•.••.......... 1-8
Keyboard Components
............••..................••.. 1-12
LIST OF FIGURES
Fi gure
1-1-1
1-3-1
1-3-2
1-3-3
1-3-4
1-3-5
1-3-6
1-3-7
Title
Major Components
ANTA Boa rd ..........•..•........•.••........•.•..........
ANT - Rtl Boa rd ......••••...........••.......•.•.•..........
SPFG Board ......•.•......•••••.•.......•.••.......•••..••
ATRPS Unit ..............................•.••...........••
WHDC Boa rd •...••.•.........••..•.•.•..•.....•..•.••.•.•.•
Floppy Disk Drive Component ..••.•.......•.•...........••.
Keyboard Component ........•.........•••...........•......
LIST OF TAßLES
Page
1-1
1-8
1-9
1-10
1-11
1-11
1-12
1-12
Table
1-3-1
1-3-2
1-3-3
1-3-4
Title Page
ANTA Board Component Descripti on .......•••.........••.•.. 1-8
ANT - Rt,1 Boa rd C ompon en tDescript ion ......•.••............. 1-9
SPFG Board Component Description •.••.•.....•.••.......... 1-10
ATRPS Un i t Outputs .........•..............•........•..••. 1-11

REV .A PROnUCT DESCRIPTIOR
1 .1 FEATURES
The EQU1TY IlI+ / EPSON pe P\f.. computer system inc1udes two major elements; a
main system unit and a keyboard.
FIGURE 1-1-1. MAJOR. COMPORKRTS
The EQU1TY II1+ / EPSON PC P\f.. hardware configuration has Cl high degree of
compatibility with the IBM AT and the new AT.
System Performance
EQU1TY 111+ / EP SON pe P\f.. has three CPU execution speeds, these are the IBN AT
speed (6 MHz), the new AT speed (8 MHz) and a fast er speed (10 l'fiIz). Speed is
selected by setting a three-position switch easily accessed from the front.
The user can see the selected execution speed by the color of a 1ED.
Wait Cycles
EQUITY IlI+ / EPSON PC P\f.. uses several types of internal devices, such as RAM,
ROM, 16-bit extension memory, 16-bit 1/0 device, 8-bit extensi on memory anel
r,-bit 1/0 device at every CPU speed. In the case of 6 MHz or 8MHz, the
number of wait cycles is the same as the AT or the new AT.
1-1

PRODUCT DESCRIPTION
WX Clock
REV.A
The clock input to the numerical processor extension (NPX) may be changed
according to the NPX version. The standard clock input is 8 MHz (AT uses 4
MHz and the new AT uses 5.33 MHz). Other clock-inputs, 20, 16, or 12 MHz
(di vided by three in the NPX) may be selected by set t ing jumper connectors on
the system board.
Mass Memory
EQU11Y 111+ / EPSON PC AX supports 4 types of built-in mass memory.
Hass Memory S lots
EQUITY 111+ / EPSON PC AX has 5 half-height slots for FDD's and IIDD's. There
are several ways to install the drives in these slots: (1) 4 half-height
drives, (2) 3 half-height drives and a full-height drive, (3) a half-height
drive and 2 full-height drives. Amaximum of four drives can be installed.
Power Supply
EQUITY 11I+ / EPSON PC AX has an IBM AT compatible power unit. Hs
specification is world wide, using 115 V /220 V, switch selected, UL/CSA and
TUV standard, and FCC/FTZ standard. The number of power cables is 4.
Multi-function Card
The
multi-function carc in the EPSON proprietary slot provides the serial
communication port, parallel printer port and floppy disk controller.
Hard Disk Controller
The hard disk controller contained in the prorietary slot will control two
hard disks.
Packaging
All switches and controls are easily accessible. Switches control the
processor execution speed, and the type of the display, color or monochrome.
1t is easy to connect the keyboard, control the volume, push the reset button,
turn the power on or off, and lock or unlock the main unit. When the unit i8
locked, the system does not accept key input and ignores the reset button.
Exterior
The unit is designed in line with the EQU1TY / EPSON PC series, which visually
distinguishes it from the numerous compatibles.
1-2

REV.A PRODUCT DESCRIPTION
1.2 SPECIFICATION
The following sections describe detail specifications by major subassembly.
F requency .
Power Consumption .....••••.
Surge Current •......•.•....
POWER SUPPLY
Input
115 VAC
230 VAC
Min. 92 V
Max.
132 V
Min. 196 V
Max. 265 V
49 -61Hz
115
VAC:
42 A O-P
Hax. 4 A
Hax.
2.5 A
230
VAC approx. 60W
(0.5 sec. more)
INSOLATION STRKRG'l'H 115 VAC: AC 1.25 kV (l min.) (AC-FG, AC-
Secondary)
230 VAC: AC 1.25 kV (1 min.) (AC-FG)
AC 3.75 kV (1 min.) (AC-Secondary)
INSOLATION RESISTANCE
ElNIRONMENT CONDITIONS
25 MOhm more (500 VDC) (AC-FG,AC-Secondary)
1
MOhm more (250 VDC) (SG-FG) (DIC short
jumper not installed)
OPERATING
Temperature 5~ to 35~
Humidity 20% to 80%
(non-condensing)
Maximum wet bulb 29 deg.
NON-OPERATING
20
° 60°C
- 'C to
10% to 90%
40 deg.
STORAGE
5% to 95%
45 deg.
Vibration
Shock (non-HDD)
Shock
(HDD)
Alti tude (HDD)
0.2 G
1 G (less than
10ms)
1 G
(less than
25mm 0-60Hz)
o to 3000 m. ASL
1 G (non-HDD)
0.5 G (HDD)
3 G (less than
10ms)
3G
(less than
25mm 0-60Hz)
-300 to 3600 m. ASL
3 G (non-HDD)
0.5 G (FIDD)
30 G (less than
(lOms)
20 G (less than
25mm 0-60Hz)
-300 to 3600 m.
ASL
1-3

PRODUCT DESCRlP TION
1.2.1 Main System Unit Specifications
PROCESSOR ••.•.•..•..•.••• 80286-10
CO-PROCESSOR •••••.••.••.. 80287-8
ROM •..•.•••.••••....•.••• 64KB (27256 x 2)
RAM ••..••......•.•..•.•.. 640KB is standard
MASS MEMORy 5 1/4" 1.2MB FDD is standard
MASS MEMORY SLOTS ••••.•.• 6 16-bit 1/0 expansion slots
3 8-bit 1/0 expansion slots
CPU CLüCK ••••.••..•.•...• 6}lliz, 8}lliz, 10 }lliz
(Switch selectable)
HAlT CYCLES ...•.•••...... Selectable
DIMENSIONS (W x D x R) ••. 498.5 x442 x169 mm
WEICHT ••.•.•..•.••.•..••. 14.5 Kg (Standard model - 1FDD)
1.2.2 Keyboard Specifications
LAYOUT ..••••••••....•..•• New AT compatible
CORD ..•••.••.••.••.•.•..• App rox. 2met ers
DIMENSIONS (W x D x H) .... 490 x 197.5 x 47.7 mm
lmICHT .•••.••.••.••..•... 1.8 Kg
1.2.3 FD1155C Floppy Disk Drive Specification
High Density Mode
REV.A
1-4
Capacity (KBytes)
Unformatted
Formatted
Transfer Rate (K-bits/sec)
Number of Tracks
Recording Density (BPI max.)
(MFM / FM)
1670 /830
1065 /532
(256 byte x 26 sector)
1229 /614 (512 byte x 15 sector)
1311 /655 (1024 byte x 8 sector)
500 /250
160
(80 tracks x 2 sides)
9870

REV.A
Normal Density Mode
PRODUCT DESCRIPTIOH
Capacity
(KBytes) (MFM
/
FM)
Unformatted
1000 /500
Formatted
655 /328 (256
byte x 16 sector)
Transfer Rate
300 /150
Number of Tracks
160 (80 tracks
x2 sides)
Recording Density
(HPI max. )5922
Seek Speed (1 track)
Seek Settling Time
Head
Loading Time
Disk Speed
Track Density
Recording Method
Power
Consumption x2
3 ms
15 ms
35 ms
360 RPM
96 TPI
HFtl/FM
4.8 w
1.2.4 MD5501-61 Floppy Disk Drive Specification
Normal Density Mode High Density Mode
Capacity (KBytes)
Unformatted
Formatted (IBM
format)
Lf8 TP I
500
327.7
(8 sector)
96 TPI
1000
655.4
(16 sector)
96 TPI
1667
1065
(26 sector)
Transfer Rate (Kbits/sec.) 300
Access Time (track-track)(ms) 10
Recording Density (BPI) 5876
Number of Tracks (p.er side) 40
300
5
5922
80
500
3
9870
80
Seek Settling Time
Disk Speed
Recording Mode
Power Consumption
15 ms
360 RPH
HFN
3.0 \v
1-5

PRODUCT DFßCRIPTION
1.2.5 D5146H Hard Disk Drive Specification
REV.A
51.24
83,328
10,416
40.30
65,536
8,192
256
615
32
256
lf
8
Capacity
Unformatted
per Cylinder
per Track
Formatted
per Cylinder
per Track
per Sector
Number of Cylinders
Sectors per Track
Bytes per Sector
Number of Disks
Number of Heads
MBytes
bytes
bytes
MBytes
bytes
bytes
bytes
Vibration
Shock
Altitude
Transfer Rate
625 KB/sec
Access Time
Track-Track
8 ms
Average Seek
40
ms
Max.
Seek
75
ms
Disk Speed 3600
RPH
Start Time 25
sec.
Stop Time 30
sec.
Recording Methoc1
MFH
Recording Density
9000 BPI
Track Density
700
'!PI
Environment Conditions
Operatin$
Temperature 5~ -4)C
Humidity 8% - 80%
(29°c)
0.2 G
2.0 G
o - 3000 m
Storage
-4dt -6&
0.5 G (0-60Hz, less than 25 nun)
20.0 G
-300 -3600 m
1-6
Power Consumption
3.0 w

REV.B PRODueT DESCRIPTION
1.2.6 BMD-720 Hard Disk Drive Specification
25.5
10,416
20.0
8,192
256
615
2460
32
256
2
4
Capacity
Unformatted
per Track
Formatted
per Track
per Sector
Number of Cylinders
Number of Tracks
Sectors per Track
Bytes per Sector
Number of Disks
Number of Heads
MBytes
bytes
MBytes
bytes
bytes
Transfer Rate
Access Time
Track-Track
Average Seek
Max. Seek
Disk Speed
Recording Method
Recording Density
Track Density
Interface
5 Mbits/sec
18 ms
69 ms
150 ms
3528 RPH +/ -1%
MFM
12900 BPI
910
'!PI
ST-506/412
Temperature
Humidity
Environment
Altitude
Conditions
Operatin&
5°C - 50C
8% - 80%
(26C)
3000 m
Storage
-40°C - 6.fC
8% - 85%
( 30C)
10000 m
Shock-Vibration
No
Soft Errors
Vibration
0.4
G,
36-500 Hz
Shock 8G, 10
os
No Hard Errors
Vibration
2G,
14-500 Hz
Shock
20 G, 10
ms
PmJer Consumption
8.0 w
3 G, 12-500 Hz
40 G, 10 ms
1-7

PRODUCT DESCRlPTION
1.3 HARDWARE CONFIGURATION
1.3.1 Hain System Unit Components
TABLE 1-3-1. ANTA BOARD COMPONENT DESCRlPTION
HEV.A
NAHE MODEL Qty
CPU 80286-10
1
NPX 80287-8
1
DMAC 8237 A-5
2
INTC 8259A 2
TIMER 8254-2
1
REAL TIME 146818
1
KEYBOARD I/F 8042
1
GAATAB E01085CB 1
GAATCB
E01086CA 1
GAA'IDB
GAATCK
GAATRF
GAATIO
E01068CA
E01068CA
E01069BB
E01092EA
1
1
1
1
FUNCTION
16 bit CPU
Co-processor (socket only)
DMA control
Interrupt control
Support 3 clock channels
System clock
t
calender and CUOS RAM
Interface between 80286 and keyboard
Controls CPU address bus (A16-0) t system
addtess bus (5A16-0) and internal address
bus (XA16-0). Generates refresh address.
Control bus (1/0 write pulset 1/0 read
pu lse t memory wri te pulse, memory read
pulse) and 7 MSB of address bus (A23-17) and
bus high enable signal.
Control CPU bus (D15-0), system data bus
(SD1S-0) and memory data bus (}ID15-0)
Clock generator, bus controller and shut
dOvrn circuit.
Controls D-RAM refresh, DHA transfer t 16-B
data bit conversioD
t
and wait state
insertion.
Address decoder for 1/0 space and r/o
registers.
1-8
FIGURE 1-3-1. ANTA BOARD

HEV.A
PRODUCT DESCRIPTION
TABLE 1-3-2. ABT-RH BOARD COMPONENT DESCRIPTION
NAME
ROH
GAATH1
GAATM2
MODEL
MB81256-10Z
MB81464-12P
uPD4164-12
27256
EOI090BA
E01091EA
Qty
18
4
2
2
1
1
FUNCTION
256Kbit dynamic RAM (Parity check RAH)
64KB x4dynamic RAM
P arity check RAM
BIaS ROM
Address decoder for memory space and parity
checker / generator for system D-RA}I.
Generates D-RAM address (MA8-0) and D-RAM
access signals (RAS, CAS and WE)
FIGURE 1-3-2. ABT-RH BOARD
1-9

PRODUCT DESCRIPTION
TABU 1-3-3. SPFG BOARD COMPONENT DESCRIPTION
HEV.A
FDC
GAATSP
GAATFD
SERIAL
CONTROLLER
MODEL
uPD765A
E01093BA
E01094BA
16450
Q'ty
1
1
Q
1
FUNcnON
Controls FDD's.
Parallel port and address decoder for serial
port.
Controls 360KB and 1.2MB diskette drives.
Includes FDOR (Floppy digital output
register), FCR (Floppy control register) and
write precornpensation circuit.
Controls serial data transfer.
1-10
FIGURE 1-3-3. SPFG BOARD