Compaq SLT 386s/20 Manual

FOREWORD
Notice
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1990 Compaq Computer Corporation.
All rights reserved. Printed in the USA.
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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:
o OPERATIONS GUIDE
o TECHNICAL REFERENCE GUIDE
o MAINTENANCE AND SERVICE GUIDE - OPTIONS AND PERIPHERALS
o MAINTENANCE AND SERVICE GUIDE - SUPPORT SOFTWARE
o MS-DOS REFERENCE GUIDE
o MS OS/2 COMMAND REFERENCE AND USER'S GUIDE
o BASIC REFERENCE GUIDE
o COMPAQ SERVICE QUICK REFERENCE GUIDE
o COMPAQ Service Advisories and Bulletins
o HOW 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:
o System Unit
o Laptop Enhanced Keyboard
o VGA Backlit Display
o 3 1/2 Inch 1.44 Megabyte Diskette Drive
o Fixed Disk Drives
o Internal Power Supply
o AC Adapter
o Battery Pack
Chapter 1.1 SYSTEM UNIT
==============================================================================
Dimensions:
Height 4.15 in. 10.54 cm
Depth 8.50 in. 29.59 cm
Width 13.50 in. 34.29 cm
Weight:
COMPAQ SLT 386s/20 Personal
Computer:

Model 120 14.0 lb 6.30 kg
Model 60 14.0 lb 6.30 kg
COMPAQ SLT/286 Personal Computer:
Model 40 14.0 lb 6.30 kg
Model 60 14.0 lb 6.30 kg
Standalone (Battery) Power
Requirements:
Nominal Operating Voltage 12 VDC 12 VDC
Average Power 8.0W 8.0W
Peak Power 11.0W 11.0W
Environmental Requirements:
Temperature Range:
Operating 50oF to 95oF 10oC to 35oC
Nonoperating -4oF to 140oF -20oC to 60oC
Relative Humidity (noncondensing):
Operating 10% to 90% 10% to 90%
Nonoperating 5% to 95% 5% to 95%
Shock and Vibrations:
Shock 40 g, 11 ms, half sine (nonoperating)
Vibration 3 g, 5 - 500 Hz 1/2 octave/minute sweep
2 hour duration (nonoperating)
1 g, 5 - 500 Hz (operating)
Maximum Unpressurized Altitude:
Operating 10,000 ft 3048 m
Nonoperating 40,000 ft 12192 m
==============================================================================
Chapter 1.2 LAPTOP ENHANCED KEYBOARD
==============================================================================
Dimensions:
Height 0.65 in. 1.65 cm
Depth 6.45 in. 16.38 cm
Width 13.50 in. 34.29 cm
Weight 1.38 lb 0.63 kg
Number of Keys 82 or 83 82 or 83
Cable:
Compressed 6.50 in. 16.51 cm
Extended 24.00 in. 60.96 cm
Interface 6 pin mini DIN 6 pin mini DIN
connector connector
Power:
Volts 5 VDC 5 VDC
Current 50 mA maximum 50 mA maximum
20 mA nominal 20 mA nominal
==============================================================================

Chapter 1.3 VGA BACKLIT DISPLAY
==============================================================================
Dimensions (image area):
Height 5.86 in. 14.88 cm
Depth 0.90 in. 2.30 cm
Width 7.81 in. 19.84 cm
Diagonal Size 10.00 in. 25.40 cm
Mounting Internal Internal
Display Compensated Compensated
Supertwist LCD Supertwist LCD
Cable:
Diameter 0.28 in. 0.71 cm
==============================================================================
Chapter 1.4 DISKETTE DRIVE
==============================================================================
1.44 MEGABYTE
------------------------------------------------------------------------------
Diskette Size 3 1/2 inch
LED Indicators:
Read/Write (high density) Green
Read/Write (low density) Orange
Capacity Per Diskette (high/low) 1.44 MB/720 Kbytes
Drives Supported Two
Drive Height Third
Drive Rotation (rpm) 300
Transfer Rate (bps) (high/low) 500K/250K
Bytes Per Sector 512
Sectors Per Track (high/low) 18/9
Tracks Per Side (high/low) 80/80
Access Times:
Track to Track (ms) 3
Average (ms) 79
Settling Time (ms) 15
Latency Average (ms) 100
Cylinders (high/low) 80/80

Read/Write Heads 2
==============================================================================
Chapter 1.5 FIXED DISK DRIVES
COMPAQ SLT 386s/20 Personal Computer
==============================================================================
120 MEGABYTE 60 MEGABYTE
------------------------------------------------------------------------------
Standard Configurations Model 120 Model 60
LED Indicators Orange Orange
Formatted Capacity Per Drive 121.56 MB 60.7 MB
Drives Supported One One
Drive Height Third Third
Drive Size 3 1/2 inch 3 1/2 inch
Drive Type 50 55
Transfer Rate (Mb/s) 12 12
Sector Interleave 1:1 1:1
Bytes Per Sector 512 512
Sectors Per Track:
Physical 40 39
Logical 39 39
------------------------------------------------------------------------------
120 MEGABYTE 60 MEGABYTE
------------------------------------------------------------------------------
Number of Surfaces:
Physical 2 2
Logical 4 4
Tracks per Surface 1053 636
Access Times (including settling):
Track to Track (ms) <5 <5
Average (ms) <19 <19
Maximum (ms) <35 <35
Physical Cylinders 1522 1522
Physical Read/Write Heads 4 2
Logical Cylinders 760 760
Logical Read/Write Heads 8 4
==============================================================================

COMPAQ SLT/286 Personal Computer
==============================================================================
40 MEGABYTE 20 MEGABYTE
------------------------------------------------------------------------------
Standard Configurations Model 40 Model 20
LED Indicators Orange Orange
Formatted Capacity Per Drive 42.9 MB 21.4 MB
Drives Supported One One
Drive Height 1 inch 1 inch
Drive Size 3 1/2 inch 3 1/2 inch
Drive Type 22 2
Transfer Rate (Mb/s) 12 10
Sector Interleave 1:1 3:1
Bytes Per Sector 512 512
Sectors Per Track:
Physical 40 33
Logical 17 40
------------------------------------------------------------------------------
40 MEGABYTE 20 MEGABYTE
------------------------------------------------------------------------------
Number of Surfaces:
Physical 2 2
Logical 4 4
Tracks per Surface 1053 636
Access Times (including settling):
Track to Track (ms) 8 8
Average (ms) 29 29
Maximum (ms) 50 50
Physical Cylinders 1053 636
Physical Read/Write Heads 2 2
Logical Cylinders 524 615
Logical Read/Write Heads 4 4
==============================================================================
Chapter 1.6 INTERNAL POWER SUPPLY
==============================================================================
Input Requirements:

Input Voltage 10 - 18.2 VDC
Input Fuse 5A (Not user accessible)
------------------------------------------------------------------------------
Power Output:
Steady State 18W
Peak 23W
------------------------------------------------------------------------------
Cooling Convection
------------------------------------------------------------------------------
VDC Output:
Nominal
Continuous Maximum
Nominal Current Current Peak Regulation
Voltage Minimum Maximum Current Tolerance
------------------------------------------------------------------------------
+ 5.00 0A 2A 3A ñ 3%
+ 12.00 0A 0.6A 1A ñ 8%
- 13.00 0A 60 mA 60 mA ñ 15%
- 26.00 0A 60 mA 60 mA ñ 15%
==============================================================================
Chapter 1.7 AC ADAPTER
==============================================================================
Dimensions:
Height 2.40 in. 6.10 cm
Depth 8.60 in. 21.84 cm
Width 3.40 in. 8.64 cm
Weight 1.66 lb 0.75 kg
Power Supply:
Operating Voltage 110 VAC/220 - 240 VAC
Steady State Power 20W
Peak Power 33W
Operating Current 1.0A
Frequency 50/60 Hz
==============================================================================
Chapter 1.8 BATTERY PACK
==============================================================================
Dimensions:
Height 1.20 in. 3.05 cm
Depth 5.40 in. 13.72 cm
Width 4.60 in. 11.68 cm
Weight 1.97 lb 0.89 kg
Power Supply:
Nominal Open Circuit Voltage 12.0 VDC
Capacity 2.4A
Power 29W
==============================================================================

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 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:
o System Board
o System Memory
o Memory Boards
o Keyboard
o Controller Circuitry
o VGA Backlit Display (Monitor)
o Fixed Disk Drives
o Diskette Drives
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
==============================================================================
Probable Recommended
Message Beeps Cause Action
------------------------------------------------------------------------------
101 - ROM Error 1 Long, System ROM 1. Inspect the ROM
1 Short placement.
2. Verify the
correct ROM.
3. Replace the ROM.
------------------------------------------------------------------------------
101 - I/O ROM Error 1 Long, System ROM 1. Inspect the ROM
1 Short placement.
2. Verify the
correct ROM.
3. Replace the ROM.
------------------------------------------------------------------------------
102 - System Board None System board Replace the system
or System Memory board.
Failure
------------------------------------------------------------------------------
162 - System 2 Short Configuration Run SETUP.
Options Error error
------------------------------------------------------------------------------
162 - System Options 2 Short Configuration Run SETUP.
Not Set incorrect
------------------------------------------------------------------------------
163 - Time & Date 2 Short Invalid time Run SETUP.
Not Set or date in
configuration
memory
------------------------------------------------------------------------------
Probable Recommended
Message Beeps Cause Action
------------------------------------------------------------------------------
164 - Memory 2 Short Configuration Run SETUP.

Size Error memory
incorrect
------------------------------------------------------------------------------
167 - RTC Lost 2 Short Real time Replace system
Power clock board.
------------------------------------------------------------------------------
XX000Y ZZ * None RAM failure 1. Replace the
201 - Memory Error memory board
(See Figure 3-1.)
2. Replace the
system board.
------------------------------------------------------------------------------
XX000Y ZZ * None RAM failure Replace the system
203 - Memory board.
Address Error
------------------------------------------------------------------------------
205 - Memory Error None Cache Memory Run DIAGNOSTICS.
error
------------------------------------------------------------------------------
301 - Keyboard Error None Keyboard Replace the
keyboard.
------------------------------------------------------------------------------
301 - Keyboard None Keyboard Replace the
Error or Test keyboard.
Fixture Installed
------------------------------------------------------------------------------
* See Section 3.3, Memory Error Codes
------------------------------------------------------------------------------
Probable Recommended
Message Beep Cause Action
------------------------------------------------------------------------------
303 - Keyboard None System board Replace the system
Controller Error keyboard board.
controller
------------------------------------------------------------------------------
304 - Keyboard or None Keyboard 1. Replace the
System Unit Error keyboard.
2. Replace the
system board.
------------------------------------------------------------------------------
401 - Printer None Printer Replace the system
Error controller board.
(COMPAQ SLT/286 only)
------------------------------------------------------------------------------
601 - Diskette None Diskette 1. Check and/or
Controller Error Controller replace cables.
circuitry 2. Run DIAGNOSTICS.
3. Replace the
system board.
------------------------------------------------------------------------------
605 - Diskette 2 Short Mismatch in Run SETUP.
Drive Error drive type
------------------------------------------------------------------------------
610 - External Storage None External Turn on External
Device Failure Storage Module Storage Module or
Hit F1 when ready attached but disconnect from
turned off computer.
------------------------------------------------------------------------------
702 - Coprocessor None Coprocessor 1. Run SETUP.

Detection Error problem; added 2. Check the
or removed the coprocessor
coprocessor installation.
3. Replace the
coprocessor.
------------------------------------------------------------------------------
1125 - Internal Serial 2 Short Defective Replace the
Port Failure internal system board.
serial port
------------------------------------------------------------------------------
1150 - Comm Port 2 Short Added or Run SETUP.
Configuration Error removed modem,
or second
serial
interface
board
------------------------------------------------------------------------------
1780 - Disk 0 None Fixed disk 1. Run DIAGNOSTICS.
Failure drive/format 2. Replace the
error drive.
------------------------------------------------------------------------------
1781 - Disk 1 None Fixed disk 1. Run DIAGNOSTICS.
Failure drive/format 2. Replace the
error drive.
------------------------------------------------------------------------------
Probable Recommended
Message Beeps Cause Action
------------------------------------------------------------------------------
1782 - Disk None Fixed disk 1. Run DIAGNOSTICS.
Controller Failure drive 2. Replace the
controller drive.
error
------------------------------------------------------------------------------
1790 - Disk 0 None Fixed disk 1. Run DIAGNOSTICS.
Error drive error 2. Replace the
drive.
------------------------------------------------------------------------------
XX000Y ZZ Parity None Parity RAM Run DIAGNOSTICS.
Check 2 failure
------------------------------------------------------------------------------
Audible * 1 Short Power on None.
successful
------------------------------------------------------------------------------
Audible * 2 Short Power on None.
successful
------------------------------------------------------------------------------
(RESUME = "F1" KEY) None As indicated Press F1 key.
to continue
------------------------------------------------------------------------------
* 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

Code Description Recommended Action
------------------------------------------------------------------------------
101 - 01 CPU test failed Replace the system board and retest
for error code 101 - 01.
------------------------------------------------------------------------------
102 - 01 Coprocessor initial The following steps apply to
status word incorrect error codes 102 - xx:
102 - 02 Coprocessor initial control 1. Run SETUP.
word incorrect 2. Replace the coprocessor and
retest.
102 - 03 Coprocessor tag word not 3. Replace the system board and
all ones retest.
102 - 04 Coprocessor tag word not
all zeros
102 - 05 Coprocessor exchange
command failed
102 - 06 Coprocessor masked
exception incorrectly handled
102 - 07 Coprocessor unmasked exception
incorrectly handled
------------------------------------------------------------------------------
Error
Code Description Recommended Action
------------------------------------------------------------------------------
102 - 08 Coprocessor wrong mask bit set The following steps apply to
in status register error codes 102 - xx:
102 - 09 Coprocessor unable to store 1. Run SETUP.
real number 2. Replace the coprocessor and
retest.
102 - 10 Coprocessor real number 3. Replace the system board and
calculation test failed retest.
102 - 11 Coprocessor speed test
failed
102 - 12 Coprocessor pattern test
failed
102 - 15 Coprocessor is inoperative
or socket is unoccupied
------------------------------------------------------------------------------
Error
Code Description Recommended Action
------------------------------------------------------------------------------
103 - 01 DMA page registers test Replace the system board and retest
failed for error codes 103 - xx through
114 - xx.
103 - 02 DMA byte controller test
failed
103 - 03 DMA word controller test
failed
104 - 01 Interrupt controller master