Computer Troubleshooting - Digital Equipment CELEBRIS Pentium PC Service Maintenance Manual

Digital CELEBRIS Pentium PC
POST and Boot Messages
Message
System CMOS checksum bad -
run SETUP
nnnn System RAM passed
System timer error
UMB upper limit segment
address: nnnn
Video BIOS shadowed

Computer Troubleshooting

Problem Possible Cause
No response Main logic board failure.
when the
Main logic board jumpers
computer is
turned on incorrectly set.
CPU has failed.
Brightness and contrast controls
Power is on, but
there is no are not correctly set.
screen display
The monitor-off timer has shut
the monitor off.
Monitor cable is incorrectly
installed.
Incorrect VGA drivers installed.
Video controller has failed.
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(continued)
Description/Solution
Correct the address conflict using the BIOS Setup utility.
If the problem persists, replace main logic board.
Where nnnn is the amount of system RAM (in kilobytes) that tested
successfully.
The computer's timer test failed.
Run the BIOS Setup utility and restore all settings to original values.
If the problem persists, replace main logic board.
Displays the address of the upper limit of UMB.
This indicates the released segments of the BIOS that can be
reclaimed by a virtual memory manager.
This indicates that the computer's video BIOS was successfully
copied to shadow RAM.
Action
Replace main logic board.
Set all appropriate jumpers (Refer to "Main logic
board jumpers").
Replace CPU.
Adjust the brightness and contrast controls.
Press [Shift] to reactivate monitor.
Check all monitor connections.
Install the correct VGA drivers.
Replace the video controller.
Troubleshooting
67