The information in this guide is subject to change without notice.
Compaq Computer Corporation shall not be liable for technical or editorial
errors or omissions contained herein; nor for incidental or consequential
damages resulting from the furnishing, performance, or use of this material.
This guide contains information protected by copyright. No part of this guide
may be photocopied or reproduced in any form without prior written consent
from Compaq Computer Corporation.
Copyright 1991 Compaq Computer Corporation.
All rights reserved.Printed in the USA
COMPAQ, DESKPRO, SYSTEMPRO, LTE, FASTART
Registered United States Patent and Trademark Office.
SLT is a trademark of Compaq Computer Corporation.
The software described in this guide is furnished under a license agreement
or nondisclosure agreement.The software may be used or copied only in
accordance with the terms of the agreement.
Product names mentioned herein may be trademarks and/or registered trademarks
of their respective companies.
MAINTENANCE AND SERVICE GUIDE
COMPAQ PORTABLE 486c Personal Computer
First Edition (October 1991)
Text Number 128987-001
Page 2
Chapter 1. Specifications
Introduction
This chapter provides physical, environmental, and performance specifications
for the following COMPAQ PORTABLE 486c Personal Computer subsystems:
o System Unit
o Full Function 101/102 Key Keyboard
o Active Matrix Color VGA Display
o Power Supply
o 3 1/2 inch 1.44 Megabyte Diskette Drive
o 210 and 120 Megabyte Fixed Disk Drives
Track to Track3 ms8 ms
Average12 ms19 ms
Maximum30 ms35 ms
Cylinders
Physical21191522
Logical683760
Read/Write Heads
Physical44
Logical168
Sectors Per Track
Physical4940
Logical38 + 1 spare39 + 1 spare
Bytes Per Sector512512
=============================================================================
Page 7
Chapter 2. Power On Self Test (POST)
Introduction
This chapter lists the subassemblies checked by the Power On Self Test (POST)
and briefly describes the types of error codes that can occur.The chapter
also includes problem isolation procedures and a flowchart for quick
reference.
Chapter 2.1 POST
POST is a series of diagnostic tests that runs automatically on the COMPAQ
PORTABLE 486c Personal Computer when it is turned on.
POST checks the following subassemblies to ensure that the computer system is
functioning properly:
o Processor Board
o Memory Module
o Keyboard
o Controller Circuitry
o Video Circuitry
o Fixed Disk Drive
o Diskette Drive
If POST finds an error in the computer, an error condition is indicated by an
audible and/or visual message.See Chapter 3, "Error Messages and Codes,"
for an explanation of the error codes and a recommended course of action.
Chapter 2.2 Preliminary Steps
If you encounter an error condition, complete the following steps before
starting the problem isolation procedures:
1.Turn off power to the computer.
2.Disconnect any external devices.Do not disconnect the printer if you
want to test the printer or use it to log error messages.
3.Install all appropriate loopback plugs and terminating plugs for complete
testing.
4.Clear the power on password, if it is preset by the user.You will know
that the power on password is set when a key icon (0--m) appears on the
screen when POST completes.If this occurs, you must enter the password
to continue.
If you do not have access to the password, you must disable the power on
password feature by setting the power on password switch (see section
2.3, "Clearing Power on Password").
Page 8
5.Access the fixed disk drive.
You will know that the fixed disk drive password is set when the
DriveLock icon (see illustration of DriveLock icon below) appears on the
screen.If this occurs, you must enter the fixed disk drive password to
continue.
IMPORTANT: It is not necessary to access the fixed disk drive in order to run
the Diagnostics diskette; however, complete system testing cannot be done
without access to the complete system.
The user must clear the fixed disk drive password or give you access
before servicing can be performed.
6.Position the brightness and volume controls approximately in the center
of their range.
7.Insert the Diagnostics diskette into drive A.
8.Turn on the computer.
9.Follow the procedures of the Problem Isolation Flowchart, section 2.4.
Refer to Chapter 3, "Error Messages and Codes," for detailed information
on problem isolation.
Chapter 2.3 Clearing Power On Password
To clear the power on password feature, reset the power on password switch
(SW5) located on the I/O board.To do so, complete the following steps:
Page 9
1.Disconnect the AC power.
2.Disassemble the computer to reach the I/O board (refer to Chapter 5).
3.Locate the power on password switch (SW5) on the I/O board; set the
switch to ON (Figure 2-1).
4.Reconnect AC power.
5.Turn on the computer and allow it to complete POST.
6.Turn the computer off.
7.Set switch SW5 to OFF.
8.Disconnect AC power.
9.Reassemble the computer (refer to Chapter 5).
10.Reconnect the AC power.
11.Turn on the computer and allow it to complete POST.If the key icon
(o--m) does not appear when POST completes, the power on password has
been cleared.
Chapter 2.4 Problem Isolation Flowchart
The problem isolation flowchart provides a quick reference for identifying
and correcting problems that may occur during POST.The flowchart gives
troubleshooting procedures for identifying malfunctions.It also directs you
to the Diagnostics chapter in the SUPPORT SOFTWARE MAINTENANCE AND SERVICE
GUIDE and to Chapter 3, "Error Messages and Codes," for more detailed
Page 10
troubleshooting information.
Page 11
Page 12
Page 13
Page 14
Page 15
Page 16
Page 17
Chapter 3. Error Messages and Codes
This chapter contains Power On Self Test (POST) messages, Diagnostic error
codes, and memory error codes for the COMPAQ PORTABLE 486c Personal Computer.
The messages and codes appear in tables that list the message or error code,
a description of the error or its probable cause, and the action recommended
to resolve the error condition.
Chapter 3.1 Power On Self Test Messages
An error message results if a problem is encountered during POST, which runs
automatically when the system is turned on.
Table 3-1 lists the messages for POST, the audible (beep) messages, probable
causes, and recommended actions.
Table 3-1.Power On Self Test Messages
=============================================================================
MessageBeepsProbable CauseRecommended Action
----------------------------------------------------------------------------205 - Memory ErrorNoneCache MemoryRun Diagnostics.
XXYYYYYcontroller or
ZZZZZZZZRAM failure
----------------------------------------------------------------------------301 - KeyboardNoneKeyboard1.Check that keyboard
Errorfailureis connected.
2.Replace the
keyboard.
----------------------------------------------------------------------------303 - KeyboardNoneProcessor board,Replace the keyboard,
Controller Errorkeyboard, ormouse or I/O board.
mouse
----------------------------------------------------------------------------304 - Keyboard orNoneKeyboard or1.Replace the
System Unitprocessor boardkeyboard.
Error2.Replace the
processor board.
----------------------------------------------------------------------------501 - Display1 Long,Video displayReplace the video board
Adapter Failure2 Shortcontroller
----------------------------------------------------------------------------601 - DisketteNoneDiskette Controller1.Replace the power
Controller Errorcircuitrydistribution board
----------------------------------------------------------------------------610 - ExternalNoneExternal StorageTurn on External
Storage ModuleModule connectedStorage Module or
Failure.Hitbut turned offdisconnect from
F1 when ready.computer.
----------------------------------------------------------------------------1151 - Comm Port 12 ShortAdded or removedRun COMPAQ EISA
Configurationmodem, or secondConfiguration utility
Errormodem boardfor error codes
1151 through 1154.
1152 - Comm Port 22 ShortAdded or removed
Configurationmodem, or second
Errormodem board
1153 - Comm Port 32 ShortAdded or removed
Configurationmodem, or second
Errormodem board
1154 - Comm Port 42 ShortAdded or removed
Configurationmodem, or second
Errormodem board
----------------------------------------------------------------------------1771 - Primary Disk2 ShortInternal andRun Diagnostics.
Port Addressexternal fixed disk
Assignmentdrive controllers
Conflictare assigned to the
primary address
----------------------------------------------------------------------------1772 - Secondary2 ShortInternal andRun Diagnostics.
Disk Port Addressexternal fixed disk
Assignmentdrive controllers
Conflictare assigned to the
secondary address
----------------------------------------------------------------------------1780 - Disk 0NoneFixed disk drive/1.Run Diagnostics.
Failureformat error2.Check and/or
replace the power
distribution board.
3.Replace the fixed
disk drive.
----------------------------------------------------------------------------1781 - Disk 1NoneFixed disk drive/1.Run Diagnostics.
Failureformat error2.Check and/or
replace the power
distribution board.
3.Replace the fixed
disk drive.
Page 20
----------------------------------------------------------------------------1782 - DiskNoneFixed disk drive1.Run Diagnostics.
Controllercontroller error2.Check and/or
Failurereplace the power
----------------------------------------------------------------------------(RESUME =NoneAs indicatedPress F1 key
"F1" KEY)to continue.
=============================================================================
Chapter 3.2 Diagnostic Error Codes
Page 21
Diagnostic error codes occur if the system recognizes a problem while running
the Diagnostics program (refer to the SUPPORT SOFTWARE MAINTENANCE AND
SERVICE GUIDE for additional information on running the Diagnostics
software).These error codes help identify possible defective subassemblies.
Tables 3-2 through 3-12 list possible error codes, a description of the error
condition, and the action required to resolve the error condition.
In each case, the Recommended Action column lists steps necessary to correct
the problem.After completing each step, run the Diagnostics program to
verify whether the error condition has been corrected.If the error code
reappears, perform the next step, then run the Diagnostics program again.
Follow this procedure until the Diagnostics program no longer detects an
error condition.
The error codes appear in an AYY XX or AAYY XX format.
A or AA = number that represents faulty assembly
YY = test or action that failed
XX = a specific problem
Example: Error code 610-21 shows that the diskette drive failed to get change
line status.
For assistance in the removal and replacement of a particular subassembly,
see Chapter 5, "Removal and Replacement Procedures."
Table 3-2.Processor Test Error Codes
=============================================================================
ErrorRecommended
CodeDescriptionAction
----------------------------------------------------------------------------101 - 0116 bit CPU failedReplace the processor board
Table 3-10.Fixed Disk Drive Test Error Codes
=============================================================================
ErrorRecommended
CodeDescriptionAction
----------------------------------------------------------------------------1700 - xxFixed disk ID driveThe following steps apply
types test failedto error codes 1700 - xx
through 1719 - xx:
1701 - xxFixed disk drive format1.Replace the fixed disk
Memory error codes appear when the system detects a memory fault during the
Power On Self Test (201 or 203 error codes) or as a result of a diagnostic
test.The TEST programs attempt to isolate the memory fault to a specific
location, then generate a memory error code.
The memory error code points to a specific memory address.The physical
location of the memory address depends on the number and type of memory
modules installed and the type of memory device used.
Memory error codes are displayed in an eight digit format (XX000Y ZZ).The
XX and Y alphanumeric codes are key identification points for defective
memory isolation.
|| |08, 10, 20, 40, 80, ??
|||
|| |00 = parity bit
|| |01 = data bit 0
|| |02 = data bit 1
|| |04 = data bit 2
|| |08 = data bit 3
|| |10 = data bit 4
|| |20 = data bit 5
|| |40 = data bit 6
|| |80 = data bit 7
|| |?? = unable to determine failed data bit.
|||
||------------------------ Failed byte.Values are 0, 1.
||
|-------------------------- Always 000.
|
----------------------------- Failed address.Values are 00 through 20.
0X = error in 1st megabyte
1X = error in 2nd megabyte
2X = error in 3rd megabyte
3X = error in 4th megabyte
Page 44
Chapter 4. Illustrated Parts Catalog
This chapter provides an illustrated parts breakdown and identifies the spare
parts for the standard features of the COMPAQ PORTABLE 486c Personal
Computer.
Chapter 4.1 Illustrated Parts Breakdown
System Unit
Page 45
Table 4-1.System Unit
=============================================================================
DescriptionSpare Part Number
Table 4-7.Processor and Standard Board Assemblies and Subassemblies
=============================================================================
Item DescriptionSpare Part Number
The following table provides a list of all of the spare part descriptions and
part numbers for standard features of the COMPAQ PORTABLE 486c Personal
Computer.Refer to the OPTIONS AND PERIPHERALS MAINTENANCE AND SERVICE GUIDE
for spare part numbers to optional features.
Table 4-9.Spare Parts List
=============================================================================
DescriptionPart Number
System Chassis128937-001
Front Bezel128946-001
Rear Panel128938-001
Handle
Connector Cover
Enhanced Option Cover
Base Panel128948-001
Tilt Base135999-001
Power Supply128898-001
Fan Assembly128901-001
Keylock135901-001
AC Power Cord (U.S./Canada)121258-001
AC Power Cord (UK)128943-001
Active Matrix Color Display:
Front Bezel128946-001
Display Assembly128902-001
Display Shield
Backlight Assembly136964-001
Display Shield
Video Cable128903-001
Display Inverter Board128900-001
Mass Storage Devices:
210 Megabyte Fixed Disk Drive128956-001
120 Megabyte Fixed Disk Drive128955-001
3 1/2 inch 1.44 Megabyte
Diskette Drive123313-001
Cables:
Power Distribution Board128935-001
Video Cable128903-001
Processor and Standard Board Assemblies
and Subassemblies:
Processor Board128897-001
4 Megabyte Memory Module118741-001
System ROM128939-001
Real Time Clock/Battery126570-001
I/O Board128949-001
Video Board128899-001
Display Inverter Board128900-001
Speaker Assembly128966-001
Keyboards:
U.S. English128958-001
Keyboard template128934-001
UK English128958-003
German128958-004
French128958-005
Italian128958-006
Spanish128958-007
Danish128958-008
Norwegian128958-009
Swedish/Finnish128958-010
Swiss128958-011
Portuguese128958-013
Latin American128958-016
Page 52
Belgian128958-018
Documentation:
Service Aids Kit105264-001
Maintenance and Service Guides:
COMPAQ PORTABLE 486c Personal Computer128987-001
Options and Peripherals Volume 1120577-001
Options and Peripherals Volume 2120577-001
Options and Peripherals Volume 3120577-001
Support Software120576-001
Operations Guide128940-001
COMPAQ PORTABLE 486c
PERSONAL COMPUTER TECHNICAL
REFERENCE GUIDE128822-001
COMPAQ SERVICE QUICK REFERENCE
GUIDE106854-001
Diagnostics
3 1/2 inch 720 Kbyte Diskette*
User Programs
3 1/2 inch 1.44 Megabyte Diskette*
----------------------------------------------------------------------------* The software spare part numbers are subject to change.Please consult the
current price list for the software spare part number before ordering.
This chapter provides module level removal and replacement procedures for the
COMPAQ PORTABLE 486c Personal Computer.
After completing all removal and replacement procedures, run the Diagnostics
program to verify that all components operate properly.Refer to the SUPPORT
SOFTWARE MAINTENANCE AND SERVICE GUIDE for information on installing new or
updated utilities when adding or removing options.
Chapter 5.1 Electrostatic Discharge
Before beginning to remove and replace a component in the COMPAQ PORTABLE
486c Personal Computer, be sure you are discharged of static electricity.
A sudden discharge of static electricity from a finger or other conductor can
destroy static sensitive devices or micro circuitry.Often the spark is
neither felt nor heard, but damage occurs.An electronic device exposed to
electrostatic discharge (ESD) may not be affected at all and will work
perfectly throughout a normal cycle.Or it may function normally for awhile,
then degrade in the internal layers, reducing its life expectancy.
Networks built into many integrated circuits provide some protection, but in
many cases, the discharge contains enough power to alter device parameters
and/or melt silicon junctions.
Generating Static
Table 5-1 shows how different methods generate static electricity and at
different electrostatic voltage levels.
----------------------------------------------------------------------------Walking across carpet35,000V15,000V7,500V
Walking across vinyl floor12,000V5,000V3,000V
Motions of bench worker6,000V800V400V
Removing DIPs from plastic tubes2,000V700V400V
Removing DIPs from vinyl trays11,500V4,000V2,000V
Removing DIPs from Styrofoam14,500V5,000V3,500V
Removing bubble pack from PCBs26,000V20,000V7,000V
Packing PCBs in foam lined box21,000V11,000V5,000V
=============================================================================
10%40%55%
NOTE:700 volts can degrade a product.
Preventing Electrostatic Damage to Equipment
Many electronic components are sensitive to ESD.Circuitry design and
structure determine the degree of sensitivity.Proper packaging and
Page 55
grounding are necessary precautions to prevent damage.Use the following
precautions to protect equipment from static damage:
o To avoid hand contact, transport products in static safe containers such as
tubes, bags, or boxes.
o Protect all electrostatic parts and assemblies by conductive or approved
containers or packaging.
o Keep electrostatic sensitive parts in their containers until they arrive at
static free stations.
o Place items on a grounded surface before removing them from their
container.
o Always be properly grounded when touching a sensitive component or
assembly.
o Place reusable electrostatic sensitive parts from assemblies in protective
packaging or conductive foam.
Use transporters and conveyors made of antistatic belts and metal roller
bushings.Mechanized equipment used for moving materials must be wired to
ground and proper materials selected to minimize static charging.When
grounding is not possible, use an ionizer to dissipate electric charges.
Preventing Damage to Drives
To prevent static damage to diskette drives and fixed disk drives, handle
drives gently and perform the following static guarding techniques:
o Store drives in their original shipping containers.
o Avoid dropping the drive from any height onto any surface.
o Handle drives on surfaces which have at least one inch of shock proof foam.
o Always place drives PCB assembly side down on the foam.
Grounding Methods
Methods for grounding must include either a wrist strap or a foot strap at a
grounded workstation.When seated, wear a wrist strap connected to a
grounded system.When standing, use footstraps and a grounded floor mat.
Table 5-2 lists different antistatic materials and their shielding protection
levels.
To provide a grounded workstation, do the following:
o Cover workstations with approved static dissipating material.Provide a
wrist strap connected to work surface and properly grounded tools and
equipment.
o Use static dissipating mats, heel straps, or air ionizers to give added
protection.
o Handle electrostatic sensitive components, parts, and assemblies by the
case or PCB laminate.Handle them only at static free workstations.
o Avoid contact with pins, leads, or circuitry.
o Turn off power and input signals before inserting and removing connectors
or test equipment to the computer.
o Use fixtures made of static safe materials when fixtures must directly
contact dissipating surfaces.
o Keep work area free of non conductive materials such as ordinary plastic
assembly aids and Styrofoam.
o Use field service tools, such as cutters, screwdrivers, vacuums, that are
conductive.
o Use a portable field service kit with a static dissipating vinyl pouch that
folds out to a work mat.Also use a wrist strap and a ground cord for the
work surface.Ground the cord to the chassis of the equipment undergoing
test or repair.
Grounding Equipment
Use the following equipment to prevent static electricity damage to
equipment:
Wrist Straps are flexible straps with a minimum of 1 megohm ñ 10%
resistance in the ground cords.To provide proper ground, a strap must be
worn snug against the skin.On grounded mats without banana plug connectors,
connect a wrist strap with alligator clips.
Heelstraps/Toestraps/Bootstraps can be used at standing workstations and are
compatible with most types of shoes or boots.On conductive floors or
dissipative floor mats, use them on both feet with a minimum of 1 megohm
resistance between operator and ground.To be effective the conductive
strips must be worn in contact with the skin.
Other materials and equipment that are recommended for use in preventing
static electricity include:
o Antistatic tape
o Antistatic smocks, aprons or sleeve protectors
o Conductive bins and other assembly or soldering aids
Page 57
o Conductive foam
o Conductive table top workstations with ground cord of 1 megohm resistance
o Static dissipating table or floor mats with hard tie to ground
o Field service kits
o Static awareness labels
o Wrist straps and footwear straps providing 1 megohm ñ 10% resistance
o Material handling packages
- Conductive plastic bags
- Conductive plastic tubes
- Conductive tote boxes
- Metal tote boxes
- Opaque shielding bags
- Transparent metallized shielding bag
- Transparent shielding tubes
Chapter 5.2 Tool and Software Requirements
To service the COMPAQ PORTABLE 486c Personal Computer, you need the
following:
o Case utility tool
o Flathead screwdriver
o Modem terminating plug
o Nonconductive probe
o ROM removal tool
o Torx screwdrivers, sizes T-10 and T-15
o 9 pin serial interface loopback plug
o 25 pin parallel interface loopback plug
Chapter 5.3 Disassembly/Assembly Sequence Chart
Use the following chart as a reference along with the procedures in this
chapter for removing and replacing the subassemblies of the COMPAQ PORTABLE
486c Personal Computer.
5.4PREPARATION PROCEDURES
|
5.5|-- KEYBOARD
|
5.6|-- REAR PANEL
||
5.7||-- OPTIONS COVER
||
5.8||-- STANDARD BOARDS
|||-- Video Board
|||-- Processor Board
|||-- System ROM
Page 58
|||-- Real Time Clock/Battery
||
5.9||-- POWER SUPPLY
||
5.10||-- FAN ASSEMBLY
||
5.11||-- I/O BOARD
|
5.12|-- BASE PANEL
|
5.13|-- MASS STORAGE DEVICES
||-- Diskette Drive
||-- Fixed Disk Drive
|
5.14|-- ACTIVE MATRIX COLOR DISPLAY
||-- Front Bezel
||-- Display Assembly
||-- Backlight Assembly
||-- Display Inverter Board
||-- Speaker Assembly
|
5.15|-- POWER DISTRIBUTION BOARD
|
5.16|-- KEYLOCK
Chapter 5.4 Preparation Procedures
Before beginning the removal and replacement procedures, complete the
following steps:
1.Turn off the computer.
2.Disconnect the AC power cord from the AC outlet and from the computer
(Figure 5-1).
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3.Disconnect all external devices (printer, monitor, and other devices)
Screws in this system are not interchangeable.As you remove screws, place
them with the component you removed.Damage may occur if you insert these
screws in the wrong place.
NOTE: The ZIF connectors in this product have mechanical latches that either
slide foreword and lift up or slide up to open.Be sure the latches on the
ZIF connectors are opened before attempting to remove the cable.
4.Carefully disconnect the video board cable from the ZIF connector
Page 65
(Figure 5-9).
5.Carefully disconnect the video cable from the video board (Figure 5-9).
6.Using a Torx T-10 screwdriver, remove the screw securing the video board
(Figure 5-9).
7.Carefully pull the video board out of the slot (Figure 5-9).
To replace the video board, reverse the steps in the above illustration.
Processor Board
To remove the processor board, complete the following steps:
1.Remove the rear panel (Section 5.6).
2.Remove the options cover (Section 5.7).
3.Remove the video board (Section 5.8).
4.Using a Torx T-15 screwdriver, remove five screws securing the processor
board to the display pan (Figure 5-10).
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5.Carefully pull the processor board out of the slot (Figure 5-10).
To replace the processor board, reverse the steps in the above illustration.
System ROM
To remove the system ROM from the processor board, complete the following
steps:
1.Remove the rear panel (Section 5.6).
2.Remove the options cover (Section 5.7).
3.Remove the video board (Section 5.8).
4.Remove the processor board.
5.Locate the system ROM on the processor board (Figure 5-11).
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6.Using the ROM removal tool, grasp the ROM and gently pull up until it is
released from the socket (Figure 5-11).
To replace the system ROM, reverse the steps in the above illustration.
NOTE: When replacing the system ROM, align Pin 1 with the dot on the system
ROM socket.
Real Time Clock/Battery
To remove the real time clock/battery, complete the following steps:
1.Remove the rear panel (Section 5.6).
2.Remove the options cover (Section 5.7).
3.Remove the video board (Section 5.8).
4.Remove the processor board (Section 5.8).
5.Locate the real time clock/battery on the processor board (Figure 5-12).
The real time clock/battery contains a lithium battery that may explode if
mishandled.Do not abuse, recharge, disassemble, or dispose of in fire.
Use only replacement real time clock/battery modules supplied by Compaq
Computer Corporation (part no. 126570-001).
Disposal of the real time clock/battery should be accomplished within
compliance of local regulations or returned to Compaq Computer Corporation by
established parts return methods.
6.Cut the tie wrap securing the real time clock/battery to the processor
board and remove the real time clock/battery (Figure 5-12).
To replace the real time clock/battery, reverse the steps in the above
illustration.
Chapter 5.9 Power Supply
To remove the power supply, complete the following steps:
1.Remove the rear panel (Section 5.6).
2.Remove the options cover (Section 5.7).
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3.Using a Torx T-15 screwdriver, remove three screws securing the power
supply to the I/O board (Figure 5-13).
4.Pull out the power supply with the switch bezel attached (Figure 5-13).
5.Remove the switch bezel from the power supply (Figure 5-13).
To replace the power supply, reverse the steps in the above illustration.
Chapter 5.10 Fan Assembly
To remove the fan assembly, complete the following steps:
1.Remove the rear panel (Section 5.6).
2.Remove the options cover (Section 5.7).
3.Carefully disconnect the fan assembly cable (Figure 5-14).
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4.Using a Torx T-10 screwdriver, remove the screw securing the fan assembly
(Figure 5-14).
5.Slide the fan assembly out (Figure 5-14).
To replace the fan assembly, reverse the steps in the above illustration.
Chapter 5.11 I/O Board
To remove the I/O board, complete the following steps:
1.Remove the rear panel (Section 5.6).
2.Remove the options cover (Section 5.7).
3.Remove the video board (Section 5.8).
4.Remove the processor board (Section 5.8).
5.Remove the power supply (Section 5.9).
6.Remove the fan assembly (Section 5.10).
7.Carefully disconnect the diskette drive cable, fixed disk drive cable,
and power cable (Figure 5-15).
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8.Disconnect the fan assembly cable (Figure 5-15).
9.Using a Torx T-10 screwdriver, remove the screw securing the internal
keyboard connector to the display pan (Figure 5-15).
10.Using a Torx T-15 screwdriver, remove seven screws securing the I/O
board (Figure 5-15).
To replace the I/O board, reverse the steps in the above illustration.
Chapter 5.12 Base Panel
To remove the base panel, complete the following steps:
IMPORTANT: The base panel cannot be removed with the cable lock provision
pulled out.Be sure the cable lock provision is completely pushed in before
performing the following steps.
1.Push in the cable lock provision (Figure 5-16).
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2.Position the computer on the rear panel (Figure 5-16).
3.Using a Torx T-15 screwdriver, remove the screw from the base panel
(Figure 5-16).
4.Remove the base panel by sliding it out toward the diskette drive side of
the computer (Figure 5-16).
To replace the base panel, reverse the steps in the above illustration.
Chapter 5.13 Mass Storage Devices
Diskette Drive
To remove the diskette drive, complete the following steps:
1.Remove the base panel (Section 5.12).
2.Carefully disconnect the cable from the diskette drive (Figure 5-17).
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3.Using a Torx T-15 screwdriver, remove the screws securing the diskette
drive cage; then swing the drive cage out (Figure 5-17).
4.Using a Torx T-15 screwdriver, remove four screws securing the diskette
drive to the drive cage (Figure 5-17).
To replace the diskette drive, reverse the steps in the above illustration.
Fixed Disk Drive
To remove the fixed disk drive, complete the following steps:
1.Remove the base panel (Section 5.12).
2.Carefully disconnect the two cables from the fixed disk drive
(Figure 5-18).
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3.Using a Torx T-15 screwdriver, remove the screws securing the fixed disk
drive cage; then swing the drive cage out (Figure 5-18).
4.Lift the fixed disk drive out of the cage and remove the shock mounts
(Figure 5-19).
To replace the fixed disk drive, reverse the steps in the above
illustrations.
Page 75
Chapter 5.14 Active Matrix Color Display
Front Bezel
To remove the front bezel, complete the following steps:
1.Remove the keyboard (Section 5.5).
2.Pull the brightness and volume controls off (Figure 5-20).
3.Remove four plastic screw covers from the front bezel (Figure 5-20).
NOTE: The ZIF connectors in this product have mechanical latches that either
slide forward and lift up or slide up to open.Be sure the latches on the
ZIF connectors are opened before attempting to remove the cable.
4.Carefully disconnect the video board cable from the ZIF connector
(Figure 5-21).
5.Carefully disconnect two display inverter board cables (Figure 5-21).
6.Remove the display assembly and the display shield (Figure 5-21).
To replace the display assembly, reverse the steps in the above
illustrations.
NOTE: The ZIF connectors in this product have mechanical latches that either
slide forward and lift up or slide up to open.Be sure the latches on the
ZIF connectors are opened before attempting to remove the cable.
4.Carefully disconnect the power distribution board cable from the ZIF
connector on the display inverter board (Figure 5-23).
5.Carefully disconnect two cables from the display assembly (Figure 5-23).
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6.Pull the display inverter board insulator aside to gain access to the
screws (Figure 5-23).
7.Using a Torx T-15 screwdriver, remove five screws securing the display
inverter board (Figure 5-23).
To replace the display inverter board, reverse the steps in the above
illustration.
Speaker Assembly
To remove the speaker assembly from the display inverter board, complete the
following steps:
1.Remove the keyboard (Section 5.5).
2.Remove the front bezel (Section 5.14).
3.Carefully disconnect the speaker assembly cable from the display inverter
board (Figure 5-24).
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4.Carefully release the speaker assembly tabs and remove the speaker
assembly from the display inverter board (Figure 5-24).
To replace the speaker assembly, reverse the steps in the above illustration.
Chapter 5.15 Power Distribution Board
To remove the power distribution board, complete the following steps:
NOTE: The ZIF connectors in this product have mechanical latches that either
slide forward and lift up or slide up to open.Be sure the latches on the
ZIF connectors are opened before attempting to remove the cable.
CAUTION
3.Carefully disconnect the power distribution cable from the ZIF connector
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on the display inverter board (Figure 5-25).
4.Turn the computer around and remove the rear panel (Section 5.6).
5.Remove the options cover (Section 5.7).
6.Remove the video board (Section 5.8).
7.Remove the processor board (Section 5.8).
8.Remove the power supply (Section 5.9).
9.Remove the fan assembly (Section 5.10).
10.Remove the I/O board (Section 5.11).
11.Remove the base panel (Section 5.12).
12.Carefully disconnect the diskette drive cable, fixed disk drive cable,
and power cable (Figure 5-26).
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13.Using a Torx T-15 screwdriver, remove four screws securing the power
distribution board (Figure 5-27).
14.Carefully pull the I/O cables, diskette drive cable, fixed disk drive
cable, and power cable through their respective slots and remove the
power distribution board (Figure 5-27).
To replace the power distribution board, reverse the steps in the above illustrations.
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Chapter 5.16 Keylock
To remove the keylock, complete the following steps:
1.Remove the rear panel (Section 5.6).
2.Remove the options cover (Section 5.7).
3.Using a flathead screwdriver, remove the metal clip securing the keylock
(Figure 5-28).
4.Pull the keylock out of the computer (Figure 5-28).
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To replace the keylock, reverse the steps in the above illustration.
Chapter 5.17 Memory Expansion
Some of the memory expansion alternatives for the COMPAQ PORTABLE 486c
Personal Computer are shown in Table 5-3.Memory modules can be added in
combinations of 2, 4, and 8 megabytes for a total of 32 megabytes.
NOTE: Memory modules can be installed in any combination and in any available
slot.However, slot 1 must contain a memory module.
Table 5-3.Memory Expansion
COMPAQ PORTABLE 486c Personal Computer
=============================================================================
This chapter provides the switch settings for the COMPAQ PORTABLE 486c
Personal Computer I/O board.The I/O board contains six switches.The
default settings shown in the following table are set for the computer as
configured by Compaq Computer Corporation.These settings need to be changed
only when the system configuration changes.
Table 6-1 lists the switch settings and describes the function of each
switch.Figure 6-1 shows the location of the switches on the I/O board.