Page 1
DECpc LPv/LPv
DEC00152
Pin 1
DEC00144-4
+
Service Guide
FRU Removals 4 of 5
ER-740WW-SV.A01
Removing the Power Supply
SIMM Removal
1 Press retaining clips out
2 Push SIMM down and pull out
DEC00153
1 Disconnect power cord
2 Remove screw securing power on/off cable from chassis
3 Remove two screws securing power supply to chassis
4 Remove four screws securing power supply to rear panel
5 Remove power supply from computer
Removing the CPU
1 Disconnect power cord
2 Unlock and remove outside cover
3 Remove CPU
4 Install CPU
5 Set appropriate jumpers
d i g i t a l
FRU Removals
5
Page 2
DECpc LPv/LPv
Pin 1
DEC00144-3
+
Service Guide
FRU Removals 3 of 5
ER-740WW-SV.A01
Removing the 5¼-Inch FDD
1 Remove two retaining screws from each side of
bottom bay
2 Remove FDD from bay
DEC00082-3
Removing Cache and Tag SRAMs
1 Use suitable device puller and gently
remove SRAM chips from sockets
2 Be especially careful not to bend or
break pins
Removing the Mounting Adapter from
the FDD
1 Remove two retaining screws from bottom
and remove adapter
FRU Removals
4
DEC00079
Removing Real-Time Clock (RTC)
1 Use device puller and gently remove RTC
from socket
Pin 1
DEC00144-2
Page 3
DECpc LPv/LPv
DEC00081-3
+
Service Guide
FRU Removals 2 of 5
Removing the Mounting Adapter
ER-740WW-SV.A01
1 Remove one retaining screw
2 Remove mounting adapter from
chassis
NOTE: Mounting bracket is required
when installing a 3 1/2 inch device in
the lower 5 1/4 inch drive bay.
Removing Filler Panels
1 Place screwdriver through hole at side
2 Release plastic locking tabs
3 Remove both filler panels
Removing the 3½-Inch FDD
1 From top bay, remove two retaining screws
from each side
2 Remove FDD from bay
3 From bottom bay, remove two retaining
screws securing mounting adapter to chassis
4 Remove FDD from bay with filler panel
DEC00078-2
DEC00076-2
d i g i t a l
DEC00080
FRU Removals
3
Page 4
DECpc LPv/LPv
DEC00092-3
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Service Guide
FRU Removals 1 of 5
ER-740WW-SV.A01
Unlocking and Removing
the Outside Cover
1 Unlock outside cover
2 Remove two retaining screws
at each side
3 Slide cover toward rear until it
clears bezel
Removing Expansion Boards
1 Remove screw
2 Gently pull board outward
Removing Internal Mounting Tray
1 Loosen four retaining screws
2 Lift out of chassis
FRU Removals
2
DEC00118-2
DEC00119-2
Removing IDE Hard Disk Drive
from Mounting Tray
1 Removing four mounting screws
2 Pull drive from mounting tray
DEC00086
Page 5
DECpc LPv/LPv
+
Service Guide
System Description 1 of 1
ER-740WW-SV.A01
DECpc LPv/LPv
Main Logic Board
CPU Intel i486
Clock Speed 25 MHz SX, 33 MHz SX,
ROM BIOS 128 KB
Cache, internal 8 KB
Cache, secondary Direct-mapped, write-back,
Expansion Slots 3 Standard ISA,
Memory
Up to 64 MB using 4 MB, 16 MB, 32-bit SIMMs
+
33 MHz DX, 50 MHz DX2,
66 MHz DX2
0 KB standard, 128 KB or
256 KB optional
8-bit and 16-bit
Power Supply
Rated Voltage Range 100 V ac - 120 V ac
220 V ac - 240 V ac
Maximum Range 88 V ac - 132 V
ac
176 V ac - 264 V ac
Rated Input Current* 3.4 A
1.8 A
Frequency Range 50 Hz - 60 Hz
DC Voltage Output +12 V dc, -12 V dc
+5 V dc, -5 V dc
* Includes outlet current
SIMM Configuration
Bank 0 Bank 1 Bank 2 Bank 3 Total
4 MB 4 MB
4 MB 4 MB 8 MB
4 MB 4 MB 4 MB 12 MB
4 MB 4 MB 4 MB 4 MB 16 MB
4 MB 16 MB 20 MB
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
d i g i t a l
System Description
1
Page 6
DECpc LPv/LPv
Jumpers 2 of 3
Main Logic Board Jumper Settings
Feature Description Setting
+
Service Guide
ER-740WW-SV.A01
Onboard VGA (IRQ9) Disable IRQ9
Enable IRQ9
Onboard VGA Enable VGA
Disable VGA
Factory test Normal
MFG test
Video display type Mono monitor
Color monitor
CPU clock speed 50 MHz J18, open
40 MHz J18, jumpered
33 MHz J18, jumpered*
25 MHz J18, open
J25, open*
J25, jumpered
J23, pins 1 and 2 jumpered*
J23, pins 2 and 3 jumpered
J28, open*
J28, jumpered
J29, open*
J29, jumpered
J19, open
J20, open
J19, open
J20, open
J19, open*
J20, jumpered*
J19, jumpered
J20, jumpered
Jumpers
8
* Factory setting
Page 7
DECpc LPv/LPv
Jumpers 1 of 3
Main Logic Board Jumper Locations
+
Service Guide
1
23
J28
J29
ER-740WW-SV.A01
J12
J11 J10
Jumpers are shown with factory settings.
d i g i t a l
J9
J25
J6
J4
J3
J23
J7
J20
J19
J18
DEC00143-2
Jumpers
7
Page 8
DECpc LPv/LPv
DEC00143-4
Power
Connectors
Hard Disk
Cable Connector
Diskette Drive
Cable Connector
Mouse
Connector
Keyboard
Connector
Mounting
Holes (4)
Front Panel
Indicators
Expansion
Board
Riser
Card
Slot
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Service Guide
FRU Removals 5 of 5
Removing the Main Logic Board
1 Disconnect all cables
2 Remove expansion board riser card
3 Remove mounting screws and lift main logic board from computer
ER-740WW-SV.A01
FRU Removals
6
Page 9
DECpc LPv/LPv
+
Service Guide
Rear Panel Connectors 3 of 3
Serial Port Connector
ER-740WW-SV.A01
The serial port is a 9-pin,
D-shell male connector
Supported baud rates are 300,
1200, 2400, 4800, 9600,
19 200, and 38 400. An asterisk (*)
after a signal name indicates an
active low signal state. For example, RXD*.
15
69
DEC00157
DB9 Signal Function
1 DCD Data Carrier Detect
2 RXD* Receive Data
3 TXD Transmit Data
4 DTR* Data Terminal Ready
5 GND Signal Ground
6 DSR Data Set Ready
7 RTS* Request To Send
8 CTS Clear To Send
9 RING Ring Indicator
Rear Panel Connectors
12
Page 10
DECpc LPv/LPv
DEC00156
13
1
25 14
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Service Guide
Rear Panel Connectors 2 of 3
Parallel Port Connector
ER-740WW-SV.A01
The parallel port connector provides
an interface for a parallel printer or
other parallel device. An asterisk(*)
after a signal name indicates an
active low signal state. For example,
STB-R*.
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
Rear Panel Connectors
11
Page 11
DECpc LPv/LPv
6
51
10
15 11
DEC00154
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Service Guide
Rear Panel Connectors 1 of 3
VGA Connector
ER-740WW-SV.A01
The VGA connector is an industry
standard, 15-pin, D-type, male connector
Pin Function
1 Red video
2 Green video
3 Blue video
4 MS2
5 Digital ground
6 Red return (ground)
7 Green return (ground)
8 Blue return (ground)
9 No connection
10 Digital ground
11 MS0
12 MS1
13 Horizontal sync
14 Vertical sync
Rear Panel Connectors
10
Keyboard and Mouse
Connectors
The keyboard and mouse connectors
are each 6-pin, mini-DIN connectors
6 16
1
DEC00155
15 No connection
Pin Function
1 Data
2 Reserved
3 Ground
4 +5 Vdc (fused)
5 Clock
6 No connection
Page 12
DECpc LPv/LPv
+
Service Guide
Jumpers 3 of 3
Main Logic Board Jumper Settings (continued)
Feature Description Setting
Cache size select 0 KB J3, open*
128 KB J3, pins 1 and 2 jumpered
256 KB J3, pins 2 and 3 jumpered
ER-740WW-SV.A01
J4, open*
J6, open*
J7, open*
J4, pins 1 and 2 jumpered
J6, pins 1 and 2 jumpered
J7, pins 1 and 2 jumpered
J4, pins 2 and 3 jumpered
J6, pins 2 and 3 jumpered
J7, pins 2 and 3 jumpered
Reset switch Enable
Disable
CPU type DX J11, pins 1 and 2 jumpered*
SX J11, pins 2 and 3 jumpered
RDY signal type VLRDY->CPURDY (VL bus ready
connects to CPU bus ready)
VLRDY->LRDY (VL bus ready
synchronized through chipset**)
Recovery mode Recovery mode
Normal
* Factory setting
** Might be required by some expansion boards
Refer to the documentation supplied with the expansion board
J9, pins 1 and 2 jumpered*
J9, pins 1 and 2 open
J12, pins 1 and 2 jumpered*
J12, pins 2 and 3 jumpered
J10, pins 1 and 2 jumpered*
J10, pins 2 and 3 jumpered
J27, jumpered
J27, open*
d i g i t a l
Jumpers
9
Page 13
DECpc LPv/LPv
+
Service Guide
Logistics and Support 1 of 1
Part Numbers
54-22703-01 Main logic board, 486SX/25
54-22703-02 Main logic board, 486SX/33
54-22703-03 Main logic board, 486DX/33
54-22703-04 Main logic board, 486D2/50
54-22703-06 Main logic board, 486D2/66
54-22703-08 Main logic board, 486SX/25*
54-22703-09 Main logic board, 486SX/33*
54-22703-10 Main logic board, 486DX/33*
54-22703-11 Main logic board, 486D2/50*
54-22703-13 Main logic board, 486D2/66*
30-41318-02 Power supply, 145W
54-22058-01 Bus card
17-00606-02 Power cord term, 110V
17-00209-15 Power cord term, 220V
17-03460-02 Flat cable, 34-pin (diskette drive)
17-03461-01 Flat cable, 40-pin (IDE drive)
-PC7XL-AA Keyboard, US
-PCXAL-AA Keyboard, US
-PCXAL-NA Keyboard, US
-PC7XS-AA Mouse, 2-button
21-39125-01 Real-time clock
-ME524-DE 4 MB SIMM, 70ns
-ME544-DE 16 MB SIMM, 70ns
-PC75M-BA 128 KB SRAM, cache memory, 0-128K upgrade
-PC74M-BA 128 KB SRAM, cache memory, 128-256K upgrade
-RX23L-AA 3.5-inch FDD, 1.44 MB
-RX33L-AA 5.25-inch FDD, 1.2 MB
-RE23R-E 3.5-inch HDD 170 MB (IDE)
-RE24L-EA 3.5-inch HDD 245 MB (IDE)*
-RE25L-EA 3.5-inch HDD 525 MB (IDE)*
-RE24M-E 3.5-inch HDD 340 MB (IDE)
-RE25LL 3.5-inch HDD 540 MB (IDE)
ER-740WW-SV.A01
* for LPv only
Related Documentation
DECpc LPv/LPv+ User's Guide
DECpc LPv/LPv+ Installation Card
Copyright © Digital Equipment Corporation 1993. All rights
reserved. The DIGITAL logo and DECpc are trademarks of
d i g i t a l
Digital Equipment Corporation.
ER-740WW-UA.A01
ER-740WW-IA.A01
Intel is a trademark of Intel Corporation.
SIMM is a trademark of Wang Laboratories.
QAPlus is a trademark of DiagSoft.
PS/2 is a trademark of International Business
Machines Corporation.
Logistics and Support
21
Page 14
DECpc LPv/LPv
+
Service Guide
Troubleshooting 8 of 8
QAPLUS Error Messages (continued)
Component Messages Solution
Floppy drive Floppy Drives Failed Check connections
ER-740WW-SV.A01
Replace drive
Battery/Clock Clock Stopped
Invalid Date
RTC Interrupt Failed
CMOS CMOS Clock Test Failed Change time from Setup
Serial port COM port failed
Serial Chip Error
Serial Compare Error
Serial Timeout Error
Onboard video
circuitry
Video Failed
Error in Video Buffer
Run Setup
Replace battery/clock
menu in QAPLUS
Check COM device
Check connections
Replace COM device
Replace main logic board
Troubleshooting
20
Page 15
DECpc LPv/LPv
+
Service Guide
Troubleshooting 7 of 8
QAPLUS Advanced Diagnostics
To:
* Receive System Information, select SysInfo menu from the main menu.
* Locate bad chips and run mouse and keyboard tests, select Interact menu.
* Edit CMOS select Setup menu.
* Run tests on components, select Testing 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
Component Messages Solution
ER-740WW-SV.A01
before
running tests.
CPU Arithmetic Function Failed
General Functions failed
Exception Interrupt in Protected Mode
Refresh Failure
Logic Functions Failed
Hard disk Butterfly Cylinder Access Test Failed
Cylinder 0 Errors
Random Cylinder Access Failed
Linear Cylinder Access Failed
Hard drive/controller Controller Diagnostic Test FAiled
Questionable Controller Card
Hard drives failed
Floppy diskette Media Mismatch
Drive Not Ready
Unformatted Media
Write Protected Media
Reset CPU
Replace CPU
Low-level format hard disk
Replace disk
Run Setup
Check connections
Reset controller
Replace controller
Replace disk
Use known good diskette
Check size and density of
diskette
Close drive door
Remove write protection
Format diskette
d i g i t a l
Troubleshooting
19
Page 16
DECpc LPv/LPv
+
Service Guide
Troubleshooting 6 of 8
DMA Channel Assignment
Channel Controller Function
0 1 Refresh
1 1 Not used
2 1 Diskette controller
3 1 ECP (optional)
4 2 Cascade DMA
ER-740WW-SV.A01
5 2 Not used
6 2 Not used
7 2 Not used
Troubleshooting
18
Page 17
DECpc LPv/LPv
+
Service Guide
Troubleshooting 5 of 8
Computer Interrupt Levels
ER-740WW-SV.A01
Priority Interrupt
Controller
1 1 IRQ0 Timer tick
2 1 IRQ1 Keyboard controller
1 IRQ2 Cascade interrupt
3 2 IRQ8 Real-time clock (RTC)
4 2 IRQ9 Reserved
5 2 IRQ10 Reserved
6 2 IRQ11 Reserved
7 2 IRQ12 Mouse interrupt
8 2 IRQ13 Math co-processor
9 2 IRQ14 Hard disk drive
10 2 IRQ15 Reserved
11 1 IRQ3 COM2, COM4
12 1 IRQ4 COM1, COM3
13 1 IRQ5 Reserved
Interrupt
Number
Interrupt
Source
d i g i t a l
14 1 IRQ6 Diskette drive
15 1 IRQ7 LPT1, LPT2, LPT3
Troubleshooting
17
Page 18
DECpc LPv/LPv
+
Service Guide
Troubleshooting 4 of 8
ER-740WW-SV.A01
I/O Address Map
Range
(hexadecimal)
46E8 VGA enable register
42E8
42E8
4AE8
82E8
86E8
8AE8
8EE8
92E8
96E8
9AE8
9EE8
A2E8
A6E8
AAE8
AEE8
B2E8
B6E8
BAE8
BEE8
E2E8
E2EA
(continued)
Function
VGA enhanced mode register
Troubleshooting
16
Page 19
DECpc LPv/LPv
+
Service Guide
Troubleshooting 3 of 8
I/O Address Map
Range
(hexadecimal)
000 - 00F DMA controller one
020 - 021 Interrupt controller one
022 Index register (85C461)
023 Data register (85C461)
040 - 043 Interval timer
060 - 06F Keyboard controller
070 - 07F Real-time clock (RTC), NMI
ER-740WW-SV.A01
Function
080 - 08F DMA page register
0A0 - 0A1 Interrupt controller two
0C0 - 0CF DMA controller two
0F0 Clear math co-processor busy
0F1 Reset math co-processor
0F8 - 0FF Math co-processor
1F0 - 1F7 IDE controller
278 - 27A LPT2
2E8 - 2EF COM4
2F8 - 2FF COM2
378 - 37A LPT1
3BC - 3BE LPT3
3E8 - 3EF COM3
3B0 - 3DF VGA registers
3F0 - 3F7 Diskette controller
3F6 - 3F7 IDE controller (alt status, device address)
d i g i t a l
3F8 - 3FF COM1
Troubleshooting
15
Page 20
DECpc LPv/LPv
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Service Guide
Troubleshooting 2 of 8
Beep Codes
Beep Codes for Fatal Errors
ER-740WW-SV.A01
Beep
Code
Error Message Port
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 DMA 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 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 64 KB RAM failure 14h
Beep
Code
Error Message Port
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 3Eh
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
Troubleshooting
14
Beep Codes for Non-Fatal Errors
Beep
Code
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
Error Message Port
80h
Page 21
DECpc LPv/LPv
+
Service Guide
Troubleshooting 1 of 8
POST Error Messages
ER-740WW-SV.A01
POST
Countdown
Number
240
200
190
180 0010 Keyboard stuck key
170 0041 Mouse failure - Check connection
160 ___ 640 KB base memory
150
050
100 0018 Invalid configuration - Run setup
Message
Number
0007
0001
0009
0017
0019
Message Solution
No timer tick
Shutdown Failure
Timer 2 failure
Controller
Clock line
Data line
Keyboard failure
0 KB extended
memory
Time-of-day clock
stopped
Time-of-day not set
Contact your Digital service
representative
- Check connections
- Check controller
- Replace keyboard
- Contact service rep.
- Check for IRQ conflict
- Replace mouse
___
- Contact service rep
- Run setup
- Replace clock
090 0011 Diskette drive failure - Run setup
080 0015 Hard disk failure
060 0021 nnnn0h optional ROM
040 0020 Keyboard locked Unlock keyboard
020 ___ Enable NMI
010 ___ Enable cache
000 ___ Boot
d i g i t a l
HDD controller failure
bad
Checksum=xxxx
- Check connections
- Replace drive
- Run setup
- Check connections
- Replace drive
- Correct address conflict
- Replace ROM chip
Troubleshooting
13
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