United States December 31, 2002
Maintenance and Service Guide
Compaq Presario 7300 Series Computers
Power-On Self
Test (POST)
Troubleshooting
without
diagnostics
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
properly functioning:
■
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.
NOTE:
An external speaker must be installed into the speaker output connector to
hear audible beeps during
POST
.
Click a link below to find the probable cause and recommended action for a given error message.
UMB Upper Limit Segment
Address
POST Messages
Error message
Probable Cause
Recommended Action
Diskette Drive A or
B Error
Drive A: or B: is present, but fails the
BIOS POST diskette tests
1. Run
2. Replace the signal cables.
3. Replace the drive.
Extended RAM
failed at offset
nnn
Extended memory not working or not
configured properly
.
Failing Bits
nnn
nnn
is a map of the bits at the RAM
address which failed the memory test
1. Run
.
Fixed Disk 0 or 1
Failure
Hard drive is not working or not
configured properly
1. Run
2. Replace the signal cable.
3. Replace the hard drive.
Fixed Disk
Controller Failure
Hard drive is not working or not
configured properly
1. Run
.
Incorrect Drive A
Type
Type of diskette in drive A: not
correctly identified
1. Run
Invalid NVRAM
Media Type
Problem with NVRAM (CMOS) access
.
Keyboard Controller
Error
Keyboard, I/O keyboard controller (on
system board), or mouse error
1. Replace the keyboard.
2. Replace the mouse.
.
Keyboard Error
Keyboard, I/O keyboard controller (on
system board), or mouse error
1. Replace the keyboard.
2. Replace the mouse.
.
Operating System
Not Found
Operating system cannot be located on
either drive A: or C:
Run
.
Parity Check 1
Parity error found in the system bus
1. Run
.
Parity Check 2
Parity error found in the I/O bus
1. Run
.
Real Time Clock
Error
Real-time clock fails BIOS test
.
System Battery is
Dead
RTC battery is dead
.
2. Run
System BIOS
Shadowed
System BIOS copied to Shadow RAM
Status message. No action required.
System Cache Error
RAM cache failed the BIOS test
Run
.
System CMOS
Checksum Bad
CMOS is corrupted or modified
incorrectly
Run
.
System RAM Failed
at Offset,
nnn
System RAM failed
Replace
.
System Timer Error
DMA, timers, etc.
.
UMB Upper Limit
Segment Address
nnn
Displays the address
nnn
of the upper
limit of Upper Memory Blocks,
indicating released segments of the
BIOS
Status message. No action required.
Video BIOS
Shadowed
Video BIOS successfully copied to
shadow RAM
Status message. No action required.