DECpc 400 MT/MTE Series Service Guide
System Description 1 of 2
EK-PCT60-SA.A02
DECpc 400 MT
System Board
CPU Intel 80486
Clock Speed 33 MHz DX, 50 MHz DX2,
66 MHz DX2
ROM BIOS 128 KB
Expansion
Slots 6 Standard ISA
CPU Upgrade via vacancy
sockets on daughter card
Memory
Up to 64 MB using 4 MB, 16 MB 36-bit SIMMs
DECpc 400 MTE
System Board
CPU Intel 80486
Clock Speed 33 MHz DX, 66 MHz DX2
ROM BIOS 128 KB FLASH
Expansion
Slots 5 Standard EISA
1 EISA or VL-Bus (VESA
compliant)
1 Dedicated local bus video
CPU Upgrade via ZIF socket
on main logic board
Memory
Up to 128 MB using 4 MB, 16 MB, 64 MB
36-bit SIMMs
Power Supply
Rated Maximum Maximum Frequency
Voltage Range* Range Input Current Range
100 Vac - 120 Vac 88 Vac - 132 Vac 8A 47 Hz - 63 Hz
220 Vac - 240 Vac 176 Vac - 264 Vac 4A 47 Hz - 63 Hz
* auto-sensing
TM
System Description
1
DECpc 400 MT/MTE Series Service Guide
System Description 2 of 2
EK-PCT60-SA.A02
DECpc 400 MT SIMM Configuration
Bank 0 Bank 1 Bank 2 Bank 3 Total
4MB 4MB
4MB 4MB 8MB
4 MB 4 MB 4 MB 12 MB
4 MB 4 MB 4 MB 4 MB 16 MB
4MB 16MB 20MB
4 MB 4 MB 16 MB 24 MB
4 MB 4 MB 16 MB 16 MB 40 MB
16 MB 16 MB
16 MB 16 MB 32 MB
16 MB 16 MB 16 MB 48 MB
16 MB 16 MB 16 MB 16 MB 64 MB
DECpc 400 MTE SIMM Configuration
Bank 0 Bank 1 Bank 2 Bank 3 Total
4MB 4MB 8MB
4MB 4MB 4MB 12MB
4 MB 4 MB 4 MB 4 MB 16 MB
4MB 16MB 20MB
4 MB 4 MB 16 MB 24 MB
4MB 16MB 16MB 36MB
4 MB 4 MB 16 MB 16 MB 40 MB
16 MB 16 MB
16 MB 16 MB 32 MB
16 MB 16 MB 16 MB 48 MB
16 MB 16 MB 16 MB 16 MB 64 MB
64 MB 64 MB
64 MB 64 MB 128 MB
Note: For optimal performance use suggested configurations. When combining SIMMs of different sizes,
be sure lower sizes are in lower banks. Failure to follow these guidelines can result in performance
degradation.
System Description
2
DECpc 400 MT/MTE Series Service Guide
FRU Removals 1 of 5
EK-PCT60-SA.A02
Removing the Side Panels
1 Remove from pedestal
2 Turn chassis key clockwise
3 Slide side panels to rear
Power
Supply
Upper
Drive
Assembly
Lower
Drive
Assembly
Fan
Assembly
Main Logic
Board
Removing Fan/Speaker Assembly
1 Remove fan and speaker connections
2 Depress tabs
3 Pull forward
LJ-02949-TI0
Removing Expansion Boards
1 Remove screw
2 Gently pull board forward
LJ-02867-TI0
LJ-02863-TI0
FRU Removals
3
DECpc 400 MT/MTE Series Service Guide
FRU Removals 2 of 5
EK-PCT60-SA.A02
Removing Lower Disk Drives
1 Remove cables and connections
2 Push up retaining clip
1 A
3 Slide drive chassis out the back
1
A
Removing Upper Disk Drives
1 Remove both side panels
2 Remove screws from both sides
3 Slide drive out front
2
LJ-02851-TI0
4 Remove screws from chassis
5 Slide drive out
LJ-02948-TI0
2
1 A
1
FRU Removals
4
A
LJ-02845-TI0
4 Remove side brackets
A
LJ-02880-TI0
DECpc 400 MT/MTE Series Service Guide
FRU Removals 3 of 5
EK-PCT60-SA.A02
CPU Chip Removal
(DECpc 400 MTE only)
1 Move lever towards the right
2 Remove chip
LOCK
FREE
FREE
LOCK
J44
J47
J41
J20
J50
J33
J7
J8
Note: When re-installing, align pin one (identified
by notch and dot) for correct orientation.
J35
J37
J36
J34
J29
J30
J31
J51
J27
J43
J43
J52
J46
J25
J23
SPK
FAN
LJ-02835-TI0
SIMM Removal
Main Logic Board Removal
1 Remove all connectors
2 Remove all expansion boards
3 Remove fan assembly
4 Remove lower drives
5 Loosen screws and slide off standoffs
LJ-02853-TI0
CPU Module Removal
(DECpc 400 MT only)
1 Remove screw
2 Unclip from fan assembly
3 Gently lift up on module and pull forward
1 Press retaining clips out
2 Push SIMM down and pull out
LJ-02879-TI0
LJ-02864-TI0
FRU Removals
5
DECpc 400 MT/MTE Series Service Guide
FRU Removals 4 of 5
EK-PCT60-SA.A02
Battery Removal
Battery (DECpc 400 MT only)
1 Remove CPU module
2 Remove battery connector
3 Gently twist battery from Velcro strip
System Battery/Real Time Clock
(DECpc 400 MTE only)
1 Pry battery/real time clock from
main logic board
Note: Use proper removal tool.
LJ-0212-AC
J44
J47
J41
J20
J50
J33
J7
J8
J43
J37
J43
J36
J35
J34
J25
J23
J29
J30
J31
J51
J52
J46
LJ-02839-TI0
J27
SPK
FAN
FRU Removals
6
DECpc 400 MT/MTE Series Service Guide
FRU Removals 5 of 5
EK-PCT60-SA.A02
Power Supply Removal
1 Remove CPU or video module
2 Remove connections
3 Remove lower and upper drives
4 Remove on/off switch
1
1
LJ-02868-TI0
5 Remove screw from power plug 2
6 Pull out power plug
7 Remove four screws from the rear
8 Slide power supply forward and out 4
2
4
3
LJ-02870-TI0
3
LJ-02871-TI0
LJ-02872-TI0
FRU Removals
7
DECpc 400 MT/MTE Series Service Guide
Switches/Jumpers 1 of 4
EK-PCT60-SA.A02
MT Main Logic Board
J22
J13 J14
J23
J25
J27
J31
Main Logic Board Jumper Settings
Feature Description Settings
On-board VGA Disable IRQ9 J13, pin 1 and 2 open (1)
Enable IRQ9 J13, pin 1 and 2 jumpered
On-board VGA Enable J14, pin 1 and 2 jumpered (1)
Disable J14, pin 1 and 2 open
CMOS Memory Normal operation J31, pin 1 and 2 jumpered (1)
Clear CMOS memory J31, pin 2 and 3 jumpered
Enable/Disable Enable RESET switch J27, pin 1 and 2 jumpered (1)
RESET switch Disable RESET switch J27, pin 2 and 3 jumpered
Parallel port Printer J25, pin 1 and 2 jumpered (1)
Bidirectional J25, pin 2 and 3 jumpered
Video display type Color monitor J29, pin 1 and 2 jumpered
Monochrome monitor J29, pin 1 and 2 open
VRAM 512 KB VRAM J22, pin 1 and 2 jumpered (1)
1 MB VRAM J22, pin 2 and 3 jumpered
Reserved Factory use only J28
VGAIOW Local J23, pin 1 and 2 jumpered (1)
Local and ISA J23, pin 2 and 3 jumpered
(1)--- Factory-default setting
J28
J29
LJ-0225-AC
Switches/Jumpers
8
DECpc 400 MT/MTE Series Service Guide
Switches/Jumpers 2 of 4
EK-PCT60-SA.A02
MTE Main Logic Board
Main Logic Board Jumper Settings
Feature Description Settings
Flash BIOS Enable J43, jumpered (1)
Upgrade Disable J43, open
CPU Select P24T J52, pin 1 and 2 jumpered
486 DX or DX2 J52, pin 2 and 3 jumpered
RESET switch Enable J46, jumpered (1)
Disable J46, open
Parallel port type Printer J20, pin 1 and 2 jumpered (1)
Bi-directional J20, pin 2 and 3 jumpered
Factory Test/ Normal Operation J23, open/parked (1)
Remove password Factory test/clear password J23, jumpered
Display type Color J25, jumpered
Mono J25, open (1)
CPU Clock input 50 MHz J34, 35, 36, 37 open
40 MHz J36 on, 34, 35, 37 off
33 MHz J35 off, 34, 36, 37 on
25 MHz J36 off, 34, 35, 37 on
Cache size select 128 KB J29, J30, J31, pin 1 and 2 jumpered (1)
256 KB J29, J30, J31, pin 2 and 3 jumpered
VL-Bus Write Wait Zero Wait Write J51, pin 1 and 2 jumpered (1)
State One Wait Write J51, pin 2 and 3 jumpered
BIOS Recovery Normal Operation J53, open (1)
Recovery mode J53, jumpered
(1)--- Factory-default setting
J44
J47
J41
J20
J50
J33
J7
J8
J37
J43
J53
J36
J35
J34
J25
J23
J29
J30
J31
J51
J52
J46
LJ-02838-TI0
SPK
FAN
Switches/Jumpers
9
DECpc 400 MT/MTE Series Service Guide
Switches/Jumpers 3 of 4
EK-PCT60-SA.A02
Analog Video Connector
The analog video connector consists
of industry-standard, 15-pin, D-type
video connector.
LJ-02946-TI0
Analog Video Connector
Pin Signal
1 Red video
2 Green video
3 Blue video
4 No connection
5 Digital ground
6 Red return (ground)
7 Green return (ground)
8 Blue return (ground)
9 Composite sync
10 Digital ground
11 No connection
12 No connection
13 Horizontal sync
14 Vertical sync
15 No connection
Keyboard and Mouse
Connectors
The keyboard and mouse connectors consist of two 6-pin, mini-DIN
connectors.
Switches/Jumpers
10
LJ-02944-TI0
Keyboard and Mouse Connector Pins
Pin Signal
1 Data
2 Reserved
3 Ground
4 +5 Vdc (fused)
5 Clock
6 No connection
DECpc 400 MT/MTE Series Service Guide
Switches/Jumpers 4 of 4
EK-PCT60-SA.A02
Parallel Printer Connector
The parallel printer connector
provides an interface to a printer or
other parallel devices. An asterisk
(*) after a signal name indicates an
active low signal. For example,
STB-R*.
LJ-02947-TI0
Parallel Printer Pinout
DB25 Pin Signal Function
1 STB-R* Strobe
2 PRTD0 Printer data bit 0
3 PRTD1 Printer data bit 1
4 PRTD2 Printer data bit 2
5 PRTD3 Printer data bit 3
6 PRTD4 Printer data bit 4
7 PRTD5 Printer data bit 5
8 PRTD6 Printer data bit 6
9 PRTD7 Printer data bit 7
10 ACK* Acknowledge
11 BUSY Busy
12 PE Paper end
13 SLCT Select
14 AUTOFDXT* Autofeed
15 ERR* Error
16 INIT* Initialize printer
17 SLCTIN* Select
18 to 25 GND Ground
Serial Port Connectors
The serial port connectors consist
of two 9-pin D-submini connectors.
The two connectors are not interchangeable. The baud rates supported by the computer's serial
ports are 300, 1200, 2400, 4800,
9600, 19 200, 38 400.
2
1
LJ-02945-TI0
9-Pin Serial Port Pinouts
DB9 Pin Signal Function
1 DCD Data carrier detect
2 RXD Receive data
3 TXD Transmit data
4 DTR Data terminal ready
5 GND Ground
6 DSR Data set ready
7 RTS Request to send
8 CTS Clear to send
9 RI Ring indicator
Switches/Jumpers
11
DECpc 400 MT/MTE Series Service Guide
Troubleshooting 1 of 7
EK-PCT60-SA.A02
POST Error Messages
POST Code Error Number Message Solution
240 0007 No timer tick
200 0001 Shutdown failure
190 0009 Timer 2 failure
180 0010 Keyboard • Check connections
170 0041 Mouse failure • Check for IRQ conflict
• Check controller
• Replace keyboard
• Replace mouse
150 0017 Time-of-day clock • Run setup
050 0019 • Replace clock
100 0018 Invalid configuration • Run setup
090 0011 Diskette drive failure • Run setup
• Check connections
• Replace drive
080 0015 Hard disk failure • Run setup
• Check connections
• Replace drive
060 0021 xxxxoh Optional • Correct address conflict
ROM Bad • Replace ROM chip
Checksum = xx
010 Enable cache
Troubleshooting
12
DECpc 400 MT/MTE Series Service Guide
Troubleshooting 2 of 7
EK-PCT60-SA.A02
Beep Codes
Beep Codes for Fatal Errors
Beep Error Port
Code Message 80H
1-1-3 CMOS Write/Read test or failure 02h
1-1-4 ROM Checksum test or failure 03h
1-2-1 Interval Timer test or failure 04h
1-2-2 DMS Initialization or failure 05h
1-2-3 DMA Page Register Write/Read test or failure 06h
1-3-1 RAM Refresh verification or failure 08h
1-3-3 1st 64 KB RAM Chip or data line failure 0Ah
1-3-4 1st 64 KB RAM Odd/even logic failure 0Bh
1-4-1 1st 64 KB RAM Address line failure 0Ch
1-4-2 1st 64 KB RAM Parity test or failure 0Dh
2-1-1 Bit 0 1st 64 KB RAM failure 10h
2-1-2 Bit 1 1st 64 KB RAM failure 11h
2-1-3 Bit 2 1st 64 KB RAM failure 12h
2-1-4 Bit 3 1st 64 KB RAM failure 13h
2-2-1 Bit 4 1st 64KB RAM failure 14h
2-2-2 Bit 5 1st 64 KB RAM failure 15h
2-2-3 Bit 6 1st 64 KB RAM failure 16h
2-2-4 Bit 7 1st 64 KB RAM failure 17h
2-3-1 Bit 8 1st 64 KB RAM failure 18h
2-3-2 Bit 9 1st 64 KB RAM failure 19h
2-3-3 Bit A 1st 64 KB RAM failure 1Ah
2-3-4 Bit B 1st 64 KB RAM failure 1Bh
2-4-1 Bit C 1st 64 KB RAM failure 1Ch
2-4-2 Bit D 1st 64 KB RAM failure 1Dh
2-4-3 Bit E 1st 64 KB RAM failure 1Eh
2-4-4 Bit F 1st 64 KB RAM failure 1Fh
Beep Error Port
Code Message 80H
3-1-1 Slave DMA register test or failure 20h
3-1-2 Master DMA register test or failure 21h
3-1-3 Master interrupt mask register test or failure 22h
3-1-4 Slave interrupt mask register test or failure 23h
3-2-4 Keyboard/mouse controller test or failure 27h
4-2-1 Timer tick interrupt test or failure 34h
4-2-2 Shutdown test or failure 35h
4-2-3 Gate A20 failure 36h
4-2-4 Unexpected interrupt in protected mode 37h
4-3-1 RAM test or failure (above 0FFFFh) 38h
4-3-3 Interval timer 2 test or failure 3Ah
4-3-4 Time of day clock test or failure 3Bh
4-4-1 Serial port test or failure 3Ch
4-4-2 Parallel port test or failure 3Dh
4-4-3 Math coprocessor test or failure 3Fh
Beep Codes for Nonfatal Errors
Beep Error Port
Code Message 80H
3-3-4 Screen memory test or failure 2Bh
3-4-1 Screen initialization or failure 2Ch
3-4-2 Screen retrace test or failure 2Dh
Troubleshooting
13
DECpc 400 MT/MTE Series Service Guide
Troubleshooting 3 of 7
EK-PCT60-SA.A02
MT/MTE I/O Address Map
Range (hexadecimal) Function
000-00F DMA Controller one
020-021 Interrupt controller one
040-043 Interval timer
060-06F Keyboard controller
070-07F Real-time clock (RTC), NMI
080-08F DMA Page register
0A0-0A1 Interrupt controller 2
0C0-0CF DMA Controller 2
0F0 Clear math coprocessor busy
0F1 Reset math coprocessor
0F8-0FF Math coprocessor
1F0-1F7 IDE Controller
2F8-2FF COM2
378-37F LPT
3B0-3DF VGA Registers
3F0-3F7 Diskette controller
3F6-3F7 IDE Controller (alt status, device address)
3F8-3FF COM1
46E8 VGA Enable register
Troubleshooting
14
DECpc 400 MT/MTE Series Service Guide
Troubleshooting 4 of 7
EK-PCT60-SA.A02
Address Map (MT only)
Range (hexadecimal) Function
42E8 VGA Enhanced mode register
4AE8
82E8
86E8
8AE8
8EE8
92E8
96E8
9AE8
9EE8
A2E8
A6E8
AAE8
AEE8
B6E8
BAE8
BEE8
E2E8
022 Index register (82C206, 82C496, 82C497)
023 Data register (82C206)
024 Data register (82C496, 82C497)
Address Map (MTE only)
Range (hexadecimal) Function
C00 EISA Configuration PAGE register
800-8FF EISA Configuration DATA register
C18 Index register (Sis 85c411V)
C1C Data register (Sis 85c411V)
C80-C83 System board ID
CA0 Index register (Sis 85c406)
CA1 Data register (Sis 85c406)
Troubleshooting
15
DECpc 400 MT/MTE Series Service Guide
Troubleshooting 5 of 7
EK-PCT60-SA.A02
Memory Map MT
Address Range Function Size
0h to 9FFFFh Base memory 640 KB
A0000h to BFFFFh Video RAM 128 KB
C0000h to C7FFFh VGA BIOS 32 KB
C8000h to DFFFFh BIOS Extension ROM 96 KB
(AT bus usage)
E0000h to EFFFFh Reserved 64 KB
F0000h to FFFFFh Computer BIOS 64 KB
100000h to 3FFFFFFh Extended memory 63 MB
Memory Map MTE
Address Range Function Size
0h to 9FFFFh Base memory 640 KB
A0000h to BFFFFh Display buffer 128 KB
C0000h to C7FFFh VGA BIOS 32 KB
C8000h to DFFFFh BIOS Extension ROM 96 KB
(AT bus usage)
E0000h to EFFFFh Reserved 64 KB
F0000h to FFFFFh Computer BIOS 64 KB
100000h to 7FFFFFFh Extended memory 127 MB
Note: After the system completes POST, the E0000h address range is available for EMS page frame.
Troubleshooting
16
DECpc 400 MT/MTE Series Service Guide
Troubleshooting 6 of 7
EK-PCT60-SA.A02
QAPlus Advanced Diagnostics
To:
• Receive System Information select the SysInfo menu on the Main Menu.
• Locate bad chips and run mouse and keyboard tests select Interact menu on the Main Menu.
• Edit CMOS select the Setup menu on the Menu.
• Run tests on components select Testing menu on the Main Menu.
Default testing is No Pause on Errors/Single Pass/No Peripherals/No Error Logging/Test All
Components. To change default, select settings under the Testing menu
QAPLUS Error Messages
before
running tests.
Component Messages Solution
CPU "Arithmetic Function Failed" • Reseat CPU
"General Functions Failed" • Replace CPU
"Exception Interrupt in Protected Mode"
"Refresh Failure"
"Logic Functions Failed"
Hard disk "Butterfly Cylinder Access Test Failed" • Low-level format hard disk
"Cylinder 0 Errors" • Replace disk
"Random Cylinder Access Test Failed"
"Linear Cylinder Access Test Failed"
Hard drive/controller "Controller Diagnostic Test Failed" • Run Setup
"Questionable Controller Card" • Check connections
"Hard Drives Failed" • Reseat controller
• Replace controller
• Replace disk
Floppy diskette "Media Mismatch" • Use known good diskette
"Drive not ready" • Check size and density of
"Unformatted media" diskette
"Write protected media" • Close drive door
• Remove write protection
• Format diskette
Troubleshooting
17
DECpc 400 MT/MTE Series Service Guide
Troubleshooting 7 of 7
EK-PCT60-SA.A02
QAPLUS Error Messages
Component Messages Solution
Floppy Drive "Floppy Drives Failed" • Check connections
Battery/Clock "Clock Stopped" • Run Setup
CMOS "CMOS Clock Test Failed" • Change time from Setup
Serial port "COM port failed" • Check COM device
Video adapter "Video Adapters Failed" • Check connections
board/Module "Error in Video Buffer" • Reseat video board
continued
• Replace drive
"Invalid Date" • Replace battery/clock
"RTC Interrupt Failed"
menu in QAPLUS
"Serial Chip Error" • Check jumpers
"Serial Compare Error" • Check connections
"Serial Timeout Error" • Reseat serial adapter board
• Replace COM device
• Replace adapter board
• Replace video board
Troubleshooting
18
DECpc 400 MT/MTE Series Service Guide
Logistics and Support 1 of 1
EK-PCT60-SA.A02
Part Numbers
74-46491-01 Bracket, CPU card (MT only)
74-46492-01 Bracket, VGA card (MTE only)
30-32969-02 3.5" 1.44 MB Floppy disk driver
12-37977-02 Key, master
54-22036-01 CPU Module, 486 DX/33 MHZ (MT only)
54-22036-01 CPU Module, 486 DX2/66 MHZ (MT only)
54-22036-02 CPU Module, 486 DX2/50 MHZ (MT only)
17-03461-02 IDE cable assembly, 40 pin, flat (MT only)
17-03461-03 IDE cable assembly, 40 pin, flat (MTE only)
17-03460-03 Floppy cable assembly, 34 pin, flat
54-22080-01 DECpc 400 MT main board
PC7XS-CA PS/2 3-Button mouse
54-22092-04 DECpc 400 MTE main board
70-30805-01 Pedestal assembly
70-30683-01 Panel assembly, side
00-H7889-AA Power supply
74-46472-01 Bezel, front
54-22092-01 VGA card, S3 805 chipset, 1 MB DRAM,
W S/W (MTE only)
54-22669-01 VGA card, S3 928 chipset, 1 MB VRAM,
W S/W (MTE only)
00-PC7XL-AA U.S. Keyboard
22-00908-03 QAPLUS Diagnostic software
70-30797-01 Fan/Speaker assembly
54-22088-01 Switch board
21-33453-02 486 DX/33 MHZ CPU chip
21-39004-02 486 DX2/66 MHZ CPU chip
00-ME524-DE 4 MB SIMM (1X36), tin 70 NS
00-ME544-DE 16 MB SIMM (4X36), tin 70 NS
00-PC74M-BA 128 KB Cache Memory Upgrade;
Four 20 NS SRAM DIPs
00-PC74M-CA 512 KB Video Memory Upgrade;
Four 80 NS VRAM ZIPs (MT S3-924 only)
00-PCT7M-CA 1 MB Video Memory Upgrade; Eight 60 NS
DRAM DIPs (MTE S3-805 VGA card and
MT S3-805 only)
00-PCT7M-CB 1 MB Video Memory Upgrade Module; 80 NS
VRAM (MTE S3-928 VGA card only)
00-PCT7M-CC 3 MB Video Memory Upgrade Module; 80 NS
VRAM (MTE S3-928 VGA card only)
12-38597-01 Battery pack, 4.5 volt (MT only)
21-39151-01 Real-Time clock W/VRAM (MTE only)
Related Documentation
DECpc 400 MT
User Information
EK-PCT60-UA
DECpc 400 MTE
User Information
EK-PCT70-UA
TM
Copyright © Digital Equipment Corportation 1993.
All Rights Reserved. The DIGITAL logo and DECpc
are trademarks of Digital Equipment Corporation.
QA Plus
User's Guide
DECpc MTE Series
Vid-805 Local Bus VGA Module
User Guide
EK-T7HEA-IA
Intel is a trademark of Intel Corporation.
SIMM is a trademark of Molex Corporation.
QAPlus is a trademark of DiagSoft.
Velcro is a registered trademark of Velcro USA, Inc.
PS/2 is a registered trademark of International Business
Machines Corporation
Logistics and Support
19
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