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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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 2
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 3
Temperature Operating 50oF to 104oF 10oC to 40oC Nonoperating -22oF to 140oF -30oC to 60oC Relative Humidity (noncondensing) Operating 20% to 80% 20% to 80% Nonoperating 5% to 90% 5% to 90% Maximum Unpressurized Altitude Operating 10,000 ft 3,050 m Nonoperating 30,000 ft 9,150 m - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 4
Width 8.3 inch 21.1 cm Diagonal Size 10.4 inch 26.4 cm Mounting Internal Internal Tilt Angle -5oF to 32oF -5oC to 32oC Display Active Matrix Active Matrix Color VGA, TFT Color VGA, TFT Color Capability 256, 16 shades 256, 16 shades per primary color per - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 5
Per Diskette (high/low) 1.44 MB/720 KB LED Indicators Read/Write (high density) Read/Write (low density) Green Orange Drives Supported One Drive Height 0.75 inch (1.9 cm) Drive Rotation (rpm) 300 Transfer Rate (bps) (high/low) 500K/250K Bytes Per Sector 512 Sectors Per Track (high/low - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 6
Drives Supported One One Form Factor 3 1/2 inch 3 1/2 inch Drive Height 1 inch 1 inch Drive Weight 1.3 lb 1.3 lb Drive Type (logical) 51 50 Drive Speed 4500 rpm 3399 rpm Transfer Rate (per second) Head Buffer (max) 20 MB 5 MB 12 MB 4.5 MB Sector Interleave 1:1 1:1 Seek Times - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 7
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 8
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 9
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 10
troubleshooting information. - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 11
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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 COMPAQ EISA Not Set incorrect or no Configuration utility. diskette drive 163 - Time and 2 Short Invalid time or Run COMPAQ - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 18
EISA Not Complete configuration Message Beeps Probable Cause Recommended Action 178 - Processor 1 Short System board type Run COMPAQ EISA Configuration invalid or step Configuration utility. does not match configuration memory XX000Y ZZ * None RAM failure 1. Replace - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 19
and retest. 2. Run Diagnostics. 3. Replace the I/O board. 605 - Diskette Drive 2 Short Mismatch in Run COMPAQ EISA Type Error drive type Configuration utility. 610 - External None External Storage Turn on External Storage Module Module connected Storage Module or Failure. Hit - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 20
Action 1790 - Disk 0 Error None Fixed disk drive 1. Run Diagnostics. error or wrong 2. Replace the drive type drive. 1791 - Disk 1 Error None Fixed disk drive 1. Run Diagnostics. error or wrong 2. Replace the drive type drive. XX000Y ZZ Parity None Parity RAM Run - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 21
recognizes a problem while running the Diagnostics program (refer to the SUPPORT SOFTWARE MAINTENANCE AND SERVICE GUIDE for additional = 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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 22
unexpected 101 - 95 Coprocessor and processor board conflict 101 - 96 Refer to Authorized Compaq Dealer Service Bulletin No. 84. Error Recommended Code Description Action 102 - 01 Coprocessor initial status The following steps apply word incorrect to error codes 102 - xx: 1. - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 23
103 - 03 DMA word controller test failed 104 - 01 Interrupt controller master test failed 104 - 02 Interrupt controller slave test failed 104 - 03 Interrupt controller software RTC is inoperative 105 - 01 Port 61 bit 6 not at zero 105 - 02 Port 61 bit 5 not at zero 105 - 03 Port 61 bit - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 24
109 - 02 CMOS clock rollover test failed 109 - 03 CMOS clock test, CMOS not properly initialized Error Recommended Code Description Action 110 - 01 Programmable timer load Replace the processor board data test failed and retest for error codes 103 - xx through 114 - xx. 110 - - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 25
113 - 50 BIOS dispatch of processor 113 - 51 Processor is unavailable or nonexistent 113 - 52 Time out waiting for completion of test 113 - 54 Time out waiting for serial semaphore 113 - 56 Unexpected interrupt occurred during test 114 - 01 Speaker test failed Table 3-3. Memory Test - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 26
204 - 02 Error during saving program memory in address test Error Recommended Code Description Action 204 - 03 Error during restore of The following steps apply program memory in to error codes 203 - xx address test through 211 - xx: 1. Replace the memory 204 - 04 A20 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 27
page not present 211 - xx Random Pattern Test 211 - 01 Memory random pattern test failed 211 - 02 Error during saving program memory and random pattern in write/read test 211 - 03 Error during restore of program memory and random pattern in write/read test 211 - 04 Insufficient memory to - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 28
Error Recommended Code Description Action 303 - 08 Keyboard LED test, The following steps apply command byte restore to error codes 301 - xx test failed through 304 - xx: 1. Check the keyboard 303 - 09 Keyboard LED test, LEDs connection. If failed to light disconnected, turn - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 29
402 - 09 Printer interrupt and data register failed 402 - 10 Printer interrupt and control register failed Error Recommended Code Description Action 402 - 11 Printer interrupt, data, and The following steps apply control register failed to error codes 401 - xx through 403 - xx - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 30
610 - xx: 601 - xx Diskette format failed 1. Replace the diskette and retest. 602 - xx Diskette read test failed 2. Replace the diskette drive and retest. 603 - xx Diskette write, read, 3. Replace the I/O board compare test failed and retest. 4. Replace the power 604 - xx Diskette - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 31
610 - 04 Previously exceeded The following steps apply maximum hard error limit to error codes 600 - xx through 610 diskette and retest. 610 - 06 Fatal error while reading 2. Replace the diskette drive and retest. 610 - 07 Fatal error while writing 3. Replace the I/O board and - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 32
- 00 Diskette drive/media ID 1. Replace the media. error, rerun COMPAQ 2. Run COMPAQ EISA EISA Configuration utility interrupt Error Recommended Code Description Action 1101 - 12 Serial Port Test; DRIVER/ Replace the I/O board and RECEIVER control signal retest for error codes - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 33
1101 - 14 Serial Port Test; DRIVER/RECEIVER data failure 1101 - 15 Serial port test modem detection 1101 - 16 Serial port test, modem ROM checksum 1101 - 17 Serial port test, tone detection - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 34
- 09 INTERRUPT circuit failure 1201 - 10 COM1 set to invalid interrupt 1201 - 11 COM2 set to invalid interrupt 1201 - 12 DRIVER/RECEIVER control signal failure Error Recommended Code Description Action 1201 - 13 UART control signal The following steps apply interrupt failure - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 35
1202 - 21 1202 - 22 Modem timed out waiting for SYNC (analog loopback answer mode) Modem timed out waiting for modem response (analog loopback answer mode) documentation for Configuration utility procedures. 2. Check the modem line. 3. Replace the modem and retest. 1202 - 23 Modem exceeded data - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 36
test failed to error codes 1700 - xx through 1719 - xx: 1701 - xx Fixed disk drive format 1. Replace the fixed disk test failed drive and retest. 2. Replace the power 1702 - xx Fixed disk drive read distribution test failed board and retest. 3. Replace the I/O board 1703 - xx Fixed - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 37
test failed retest. 3. Replace the I/O board Fixed disk drive Error Correction and retest. Code test failed 1719 - xx Fixed disk drive power mode test 1719 - 01 Exceeded maximum soft error limit 1719 - 02 Exceeded maximum hard error limit 1719 - 03 Previously exceeded maximum soft error - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 38
xx: 1719 - 50 Failed file I/O write test 1. Replace the fixed disk drive and retest. 1719 - 51 Failed file I/O read test 2. Replace the power track distribution board and retest. 1719 - 66 Failed initial drive 3. Replace the I/O board parameter and retest. 1719 - 67 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 39
failed 1901 - xx through 1906 - xx: 1902 - xx Tape format failed 1. Replace the tape cartridge and retest. 1903 - xx Tape drive sensor test 2. Replace the tape drive failed and retest. 3. Replace the I/O board 1904 - xx Tape BOT/EOT test failed and retest. 1905 - xx Tape read test - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 40
Replace the I/O board 1906 - 13 Tape not formatted and retest. 1906 - 14 Drive timeout error 1906 - 15 Sensor error flag 1906 - 16 Block locate (block ID) error 1906 - 17 Soft error limit exceeded 1906 - 18 Hard error limit exceeded 1906 - 19 Write (probably ID) error 1906 - 20 NEC - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 41
1906 - 34 No data detected 1906 - 35 Power on reset occurred 1906 - 91 Power lost during test Table 3-12. Video Test Error Codes Error Recommended Code Description Action 2402 - 01 Video memory test failed Replace the video board and retest for error 2403 - 01 Video - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 42
Codes Error Recommended Code Description Action 8601 - xx Pointing Device Interface 1. Install new copy of test failed mouse driver software. 2. Replace with a working pointing device and retest. 3. Replace the I/O board and retest. Chapter 3.3 Memory Error Codes Memory - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 43
| || 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. | || - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - 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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 45
Table 4-1. System Unit Description Spare Part Number 1. System Chassis 128937-001 2. Front Bezel 128946-001 3. Rear Panel Handle Connector Cover Enhanced Option Cover 128938-001 4. Base Panel 128948-001 5. Tilt Base 135999-001 6. Power Supply 128898-001 7. Fan Assembly 128901 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 46
001 4. Video Cable 128903-001 5. Display Inverter Board 128900-001 Mass Storage Devices Table 4-3. Mass Storage Devices Description Spare Part Number 1. 210 Megabyte Fixed Disk Drive 128956-001 2. 120 Megabyte Fixed Disk Drive 128955-001 3. 3 1/2 inch 1.44 Megabyte Diskette - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 47
Table 4-4. Cables Description Spare Part Number 1. Power Distribution Board 128935-001 2. Video Cable 128903-001 Processor Board - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 48
Memory Module Connector, Slot 1 I/O Board Table 4-6. COMPAQ PORTABLE 486c Personal Computer I/O Board Connectors 1. Enhanced Option Connector 2. Internal Keyboard Connector 3. Fan Assembly Connector 4. Diskette Drive Connector 5. Fixed Disk Drive Connector 6. Processor Slot 7. Video Slot 8. Audio - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 49
Table 4-7. Processor and Standard Board Assemblies and Subassemblies Item Description Spare Part Number 1. Processor Board 128897-001 2. 4 Megabyte Memory Module 118741-001 3. System ROM 128939-001 4. Real Time Clock/Battery 126570-001 5. I/O Board 128949-001 6. Video Board - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 50
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 Description Part Number - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 51
Board 128946-001 128902-001 136964-001 128903-001 128900-001 Mass Storage Devices: 210 Megabyte Fixed Disk Drive 120 Megabyte Fixed Disk Drive 3 1/2 inch 1.44 Megabyte Diskette Drive 128956-001 128955-001 123313-001 Cables: Power Distribution Board Video Cable 128935-001 128903-001 Processor - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 52
Support Software 120576-001 Operations Guide 128940-001 COMPAQ PORTABLE 486c PERSONAL COMPUTER TECHNICAL REFERENCE GUIDE 128822-001 COMPAQ SERVICE QUICK REFERENCE GUIDE Backlight cable Diskette drive cage ground strap Display inverter board insulator Fixed disk drive ground strap Enhanced - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 53
Screw Kit 6-32, MA, TH, T-15, CS 136967-001 Screw Kit 6-32 x 1/4, Torx, TT, HI, T/WSr 119548-001 Screw Kit 6-32 x 1/4, S-Torx, PNHD 136966-001 Screw Kit 6-32 x 1/4, TAPTITE, HT 128212-001 Screw Kit 136974-001 6-32 x 1/2, S-Torx, TT - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 54
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 55
, 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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 56
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 57
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 shielding tubes Chapter 5.2 Tool and Software Requirements To service the COMPAQ PORTABLE 486c Personal Computer, you need the following: o - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 58
Battery || | |-- POWER SUPPLY || | |-- FAN ASSEMBLY || | |-- I/O BOARD | |-- BASE PANEL | |-- MASS STORAGE DEVICES | |-- Diskette Drive | |-- Fixed Disk Drive | |-- ACTIVE MATRIX COLOR DISPLAY | |-- Front Bezel | |-- Display Assembly | |-- Backlight Assembly | |-- Display Inverter - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 59
3. Disconnect all external devices (printer, monitor, and other devices) from the computer. CAUTION Static electricity can damage the CMOS components. Be sure that you are properly grounded before performing any of the following procedures CAUTION Screws in this system are not interchangeable. - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 60
2. Using a nonconductive probe, remove the access cover (Figure 5-3). 3. Disconnect the keyboard cable by gently pulling the keyboard connector tab (Figure 5-4). - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 61
4. Carefully remove the keyboard cable from the cable slot (Figure 5-4). To replace the keyboard, reverse the steps in the above illustrations. Chapter 5.6 Rear Panel To remove the rear panel, complete the following steps: 1. Push the tilt adjustment buttons on the sides of the computer in and tilt - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 62
2. Lift the handle and remove two screws, using a Torx T-15 screwdriver (Figure 5-5). 3. Pull the rear panel out and up, until the bottom latches are released from the slots (Figure 5-6). To replace the rear panel, complete the following steps: 1. Position the rear panel on the computer by aligning - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 63
with the appropriate slots. 2. Slide the rear panel down and forward, and secure with the two screws using a Torx T-15 screwdriver. Chapter 5.7 Options Cover To remove the options cover, complete the following steps: 1. Remove the rear panel (Section 5.6). 2. Using a Torx T-15 screwdriver, remove - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 64
(Section 5.6). 2. Remove the options cover (Section 5.7). 3. Remove any expansion boards from the expansion slots (Refer to the COMPAQ PORTABLE 486c Personal Computer Reference Guide). CAUTION When removing or inserting cables with Zero Insertion Force (ZIF) connectors, do not pull, twist, or - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - 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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 66
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 67
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 68
(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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 69
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 70
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). - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 71
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, - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 72
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 73
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 74
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. - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - 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 WARNING The - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 76
Display Assembly To remove the display assembly, complete the following steps: 1. Remove the keyboard (Section 5.5). 2. Remove the front bezel (Section 5.14). WARNING The display inverter board contains High Voltage. Avoid contact with all surfaces of the display inverter board when removing the - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 77
CAUTION When removing or inserting cables with ZIF connectors, do not pull, twist, or apply tension to cables 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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 78
4. Place the display assembly screen down on a soft, clean surface. 5. Using a Phillips screwdriver, remove the four screws securing the display assembly to the backlight assembly (Figure 5-22). 6. Carefully release the display assembly cables from the four corner brackets (Figure 5-22). 7. Release - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 79
1. Remove the keyboard (Section 5.5). 2. Remove the front bezel (Section 5.14). 3. Remove the display assembly (Section 5.14). WARNING The display inverter board contains high voltage. Avoid contact with all surfaces of the board CAUTION When removing or inserting cables with ZIF connectors, do - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 80
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 81
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 82
(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). - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 83
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 84
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 85
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 - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 86
4 MB 2 MB 8 MB 8 MB 22 MB 4 MB 4 MB 8 MB 8 MB 24 MB 4 MB 8 MB 8 MB 8 MB 28 MB | | | | | | | | | | 8 MB 8 MB 8 MB 8 MB 32 MB - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 87
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 Diskette Drive. OFF is the default position and allows Read/Write capability. ON sets the diskette drive for - Compaq Portable 486 | Compaq Portable 486c Personal Computer Maintenance and Ser - Page 88
SW5 ON Enabled Controls the power on OFF Disabled password. OFF is the default position and enables the power on password feature. ON will clear the power on password. SW6 ON Enabled Allows the configuration OFF Disabled memory to be cleared. OFF is the default position and
Notice
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