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MAINTENANCE AND SERVICE GUIDE
COMPAQ SLT 386s/20 PERSONAL COMPUTER,
COMPAQ SLT/286 PERSONAL COMPUTER
First Edition (June 1990)
Text PN 118385-001
Preface
THE MAINTENANCE AND SERVICE GUIDE COMPAQ SLT 386s/20 PERSONAL COMPUTER,
COMPAQ SLT/286 PERSONAL COMPUTER is a troubleshooting guide.It can be used
as a reference when servicing the COMPAQ SLT 386s/20, Model 60 and Model 120,
or the COMPAQ SLT/286, Model 20 and Model 40.Compaq Computer Corporation
reserves the right to make changes to the computers without notice.The
diagrams and procedures in this document apply to these computers.Diagnostic
tests are designed to test only these products.
Interpreting Symbols
WARNING:TEXT SET OFF IN THIS MANNER INDICATES THAT FAILURE TO FOLLOW
DIRECTIONS IN THE WARNING COULD RESULT IN BODILY HARM OR LOSS OF LIFE.
CAUTION:TEXT SET OFF IN THIS MANNER INDICATES THAT FAILURE TO FOLLOW
DIRECTIONS COULD RESULT IN DAMAGE TO EQUIPMENT OR LOSS OF DATA.
IMPORTANT:Text set off in this manner presents clarifying information or
specific instructions.
NOTE:Text set off in this manner presents commentary sidelights, or
interesting points of information.
Locating Additional Information
The following documentation is available for the COMPAQ SLT 386s/20 and
COMPAQ SLT/286 Personal Computers:
oOPERATIONS GUIDE
oTECHNICAL REFERENCE GUIDE
oMAINTENANCE AND SERVICE GUIDE - OPTIONS AND PERIPHERALS
oMAINTENANCE AND SERVICE GUIDE - SUPPORT SOFTWARE
oMS-DOS REFERENCE GUIDE
oMS OS/2 COMMAND REFERENCE AND USER'S GUIDE
oBASIC REFERENCE GUIDE
oCOMPAQ SERVICE QUICK REFERENCE GUIDE
oCOMPAQ Service Advisories and Bulletins
oHOW TO DO BUSINESS WITH COMPAQ CUSTOMER SERVICE
Technician Notes
CAUTION:ONLY AUTHORIZED TECHNICIANS TRAINED BY COMPAQ SHOULD ATTEMPT TO
REPAIR THIS EQUIPMENT.ALL TROUBLESHOOTING AND REPAIR PROCEDURES ARE DETAILED
TO ALLOW ONLY SUBASSEMBLY/MODULE LEVEL REPAIR.BECAUSE OF THE COMPLEXITY OF
THE INDIVIDUAL BOARDS AND SUBASSEMBLIES, NO ONE SHOULD ATTEMPT TO MAKE REPAIRS
AT THE COMPONENT LEVEL OR TO MAKE MODIFICATIONS TO ANY PRINTED WIRING BOARD.
IMPROPER REPAIRS CAN CREATE A SAFETY HAZARD.ANY INDICATIONS OF COMPONENT
REPLACEMENT OR PRINTED WIRING BOARD MODIFICATIONS MAY VOID ANY WARRANTY OR
EXCHANGE ALLOWANCES.
Chapter 1 - Specifications
INTRODUCTION
This chapter provides physical, environmental, and performance specifications
for the following COMPAQ SLT 386s/20 Personal Computer and the COMPAQ SLT/286
Personal Computer subsystems:
oSystem Unit
oLaptop Enhanced Keyboard
oVGA Backlit Display
o3 1/2 Inch 1.44 Megabyte Diskette Drive
oFixed Disk Drives
oInternal Power Supply
oAC Adapter
oBattery Pack
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 SLT 386s/20 and COMPAQ SLT/286 Personal Computers when the computers
are turned on.
POST checks the following subassemblies to ensure that the computer system is
functioning properly:
POST also detects the type of mass storage devices installed in the computer.
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.Do not remove the battery pack.
2.Disconnect any external devices (leave the AC Adapter attached). 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.
NOTE:The COMPAQ SLT 386s/20 has a power on password feature.You will
know that the power on password is set when a key icon (o--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 resetting the password switch on the system board (see
section 2.3, "Clearing Power On Password").
5.Position the brightness and contrast controls approximately in the center
of their range.
6.Insert the DIAGNOSTICS diskette into drive A.
7.Turn on the computer.
8.Follow the procedures of the Problem Isolation Flowchart in 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 on the COMPAQ SLT 386s/20, disable the
power on password by resetting the system board switch.To do so, complete
the following steps:
1.Disconnect the AC power.
2.Disassemble the computer to reach the system board (refer to Chapter 5).
3.Locate switch SW1 on the system board (Figure 2-1).
4.Change switch SW1-2 to the ON position (disable).
5.Reassemble the computer (refer to Chapter 5); then reconnect the AC power.
6.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.
To reset or enable the power on password switch, follow these steps:
1.Turn off the computer and disconnect the AC power.
2.Disassemble the computer to reach the system board (refer to Chapter 5).
3.Reset switch SW1-2 to the OFF position (enable).
4.Reassemble the computer.
5.Reconnect the AC power and turn on the computer.
IMPORTANT:If the power on password switch is not reset to its original
position, it will be impossible to reestablish the password.
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 MAINTENANCE AND SERVICE GUIDE SUPPORT
SOFTWARE and to Chapter 3, "Error Messages and Codes," for more detailed
troubleshooting information.
Chapter 3 - Error Messages and Codes
INTRODUCTION
This chapter contains Power On Self Test (POST) messages, DIAGNOSTIC error
codes, and memory error codes.
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
==============================================================================
MessageBeepsCauseAction
-----------------------------------------------------------------------------101 - ROM Error1 Long,System ROM1.Inspect the ROM
1 Shortplacement.
-----------------------------------------------------------------------------101 - I/O ROM Error1 Long,System ROM1.Inspect the ROM
1 Shortplacement.
-----------------------------------------------------------------------------102 - System BoardNoneSystem boardReplace the system
or System Memoryboard.
Failure
-----------------------------------------------------------------------------301 - Keyboard ErrorNoneKeyboardReplace the
keyboard.
-----------------------------------------------------------------------------301 - KeyboardNoneKeyboardReplace the
Error or Testkeyboard.
Fixture Installed
-----------------------------------------------------------------------------* See Section 3.3, Memory Error Codes
304 - Keyboard orNoneKeyboard1.Replace the
System Unit Errorkeyboard.
2.Replace the
system board.
-----------------------------------------------------------------------------401 - PrinterNonePrinterReplace the system
Errorcontrollerboard.
(COMPAQ SLT/286 only)
-----------------------------------------------------------------------------605 - Diskette2 ShortMismatch inRun SETUP.
Drive Errordrive type
-----------------------------------------------------------------------------610 - External StorageNoneExternalTurn on External
Device FailureStorage ModuleStorage Module or
Hit F1 when readyattached butdisconnect from
or removed thecoprocessor
coprocessorinstallation.
3.Replace the
coprocessor.
-----------------------------------------------------------------------------1125 - Internal Serial2 ShortDefectiveReplace the
Port Failureinternalsystem board.
serial port
-----------------------------------------------------------------------------1150 - Comm Port2 ShortAdded orRun SETUP.
Configuration Errorremoved modem,
or second
serial
interface
board
-----------------------------------------------------------------------------1780 - Disk 0NoneFixed disk1.Run DIAGNOSTICS.
Failuredrive/format2.Replace the
errordrive.
-----------------------------------------------------------------------------1781 - Disk 1NoneFixed disk1.Run DIAGNOSTICS.
Failuredrive/format2.Replace the
* Beeps can be disabled by the user during the SETUP program.
==============================================================================
Chapter 3.2 DIAGNOSTIC ERROR CODES
DIAGNOSTIC error codes occur if the system recognizes a problem while running
the COMPAQ DIAGNOSTICS program (refer to the MAINTENANCE AND SERVICE GUIDE
SUPPORT SOFTWARE for additional information on running the DIAGNOSTICS
software).These error codes help identify possible defective subassemblies.
Tables 3-2 through 3-11 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
==============================================================================
Error