Compaq 7470 - Presario - 64 MB RAM Maintenance And Service Manual page 14

MSG index Product Description
Home Removal & Replacement
Troubleshooting
Clearing CMOS
Power-On Self Test
(POST)
Configuration
Diagnostics Software
Troubleshooting without
diagnostics
Maintenance and Service Guide
Compaq Presario 7400 Series Computers
TROUBLESHOOTING
Power-On Self Test (POST)
POST is a series of diagnostic tests that run automatically when the system is turned on. After the
computer is turned on, POST checks the following assemblies to ensure that the computer system is
functioning properly:
Keyboard
System board
Memory modules
Video memory
Diskette drives
Hard drive
Power supply
POST also detects the type of mass storage devices installed in the computer.
If POST finds an error in the system, an error condition is indicated by an audible and/or visual
message. The table below gives explanations of the error codes and a recommended course of action.
An external speaker must be installed into the speaker output connector to
NOTE:
hear audible beeps during POST.
Click a link below to find the probable cause and recommended action for a given error message.
Diskette Drive A or B Error
Extended RAM failed at
offset nnn
Failing Bits nnn
Fixed Disk 0 or 1 Failure
Fixed Disk Controller Failure
Incorrect Drive A Type
Invalid NVRAM Media Type
Error message
Diskette Drive A or Drive A: or B: is present, but fails the
B Error BIOS POST diskette tests
Extended RAM Extended memory not working or not
failed at offset nnn configured properly
Failing Bits nnn nnn is a map of the bits at the RAM
address which failed the memory test
Fixed Disk 0 or 1 Hard drive is not working or not
Failure configured properly
Fixed Disk Hard drive is not working or not
Controller Failure configured properly
Incorrect Drive A Type of diskette in drive A: not
Type correctly identified
Invalid NVRAM Problem with NVRAM (CMOS) access
Media Type
Keyboard Controller Keyboard, I/O keyboard controller (on
Error system board), or mouse error
Keyboard Error Keyboard, I/O keyboard controller (on
system board), or mouse error
Operating System Operating system cannot be located on
Not Found either drive A: or C:
Parity Check 1 Parity error found in the system bus
Parity Check 2 Parity error found in the I/O bus
Real Time Clock Real-time clock fails BIOS test
Error
System Battery is RTC battery is dead
Dead
System BIOS System BIOS copied to Shadow RAM
Shadowed
System Cache Error RAM cache failed the BIOS test
System CMOS CMOS is corrupted or modified
Checksum Bad incorrectly
System RAM Failed System RAM failed
at Offset, nnn
System Timer Error DMA, timers, etc.
UMB Upper Limit Displays the address nnn of the upper
Segment Address limit of Upper Memory Blocks,
nnn indicating released segments of the
BIOS
Video BIOS Video BIOS successfully copied to
Shadowed shadow RAM
Troubleshooting
Jumper & Switch Information
Keyboard Controller Error
Keyboard Error
Operating System Not
Found
Parity Check 1
Parity Check 2
Real Time Clock Error
System Battery is Dead
POST Messages
Probable Cause
Illustrated Parts Catalog
Specifications
System BIOS Shadowed
System Cache Error
System CMOS Checksum Bad
System RAM Failed at Offset, nnn
System Timer Error
UMB Upper Limit Segment
Address nnn
Video BIOS Shadowed
Recommended Action
1. Run Setup.
2. Replace the signal cables.
3. Replace the drive.
1. Replace the memory modules.
2. Replace the system board.
1. Run Setup.
2. Replace the system board.
1. Run Setup.
2. Replace the signal cable.
3. Replace the hard drive.
1. Run Setup.
2. Replace the system board.
1. Run Setup.
2. Replace the diskette drive.
Replace the system board.
1. Replace the keyboard.
2. Replace the mouse.
3. Replace the system board.
1. Replace the keyboard.
2. Replace the mouse.
3. Replace the system board.
Run Setup.
1. Run Setup.
2. Replace the memory modules.
3. Replace the system board.
1. Run Setup.
2. Replace the ISA board
Replace the system board.
1. Replace the RTC battery.
2. Run Setup.
Status message. No action required.
Run Setup.
Run Setup.
Replace memory modules.
Replace the system board.
Status message. No action required.
Status message. No action required.
(modem).