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When I first turn on the computer the start button flashes green for about a second turns off and the fan shuts down. Then the same thing repeats and turns off. The diagnostic lights 2 & 3 turn green for less than a second then turn off, then 1 and 4 turn on for less than a second then the machine shuts down. I checked the power supply by jumping het green and black wires on the main connector and all the voltages were correct. I also disconnected the hard and DVD drivers with the same results. Do I have a defective motherboard ?
330
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Posted August 4th, 2011 06:00
Not aware of such a model C421. Perhaps you mean C521.
Remove all expansion cards, Disconnect all drive data cables, Remove all Ram.
It should beep and show ram error.
1 and 4 means system board failure.
Test ram modules 1 at a time then put them back in pairs.
Diagnostic Lights - Documentation
System Lights
Your power button light and hard-drive activity light may indicate a computer problem.
Power Light
Problem Description
Suggested Resolution
Off
The computer is in a normal "off" condition or in a power-conserving mode.
None. Press the power button to wake the computer or to turn the computer on.
Solid green
The computer has successfully booted and is operating normally.
None.
Blinking green
The computer is in a Windows standby power-saving state (S1 or S3).
None. Move the mouse, press the spacebar, or use another device that has been configured as a wake-up device to wake the computer.
Solid Amber
A pre-POST failure has occurred. The system has received a Power Good signal from the power supply.
See Diagnostic Lights for more information.
If this does not resolve your problem, contact Dell. For information about contacting Dell, see your Owner's Manual.
Blinking Amber
A possible power supply failure has occurred. The system has not received a Power Good signal from the power supply
Plug the computer into a working electrical outlet.
Memory modules are detected, but a memory failure has occurred.
- If you have two or more memory modules installed, remove the modules, reinstall one module (see Memory), and then restart the computer. If the computer starts normally, reinstall an additional module. Continue until you have identified a faulty module or reinstalled all modules without error.
- If available, install properly working memory of the same type into your computer (see Memory).
- If the problem persists, contact Dell. For information about contacting Dell, see your Owner's Manual.
Diagnostic Lights
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions in the Product Information Guide. To help you troubleshoot a problem, your computer has four lights labeled "1," "2," "3," and "4" on the front panel. When the computer starts normally, the lights flash. After the computer starts, all four lights display solid green. If the computer malfunctions, the color and sequence of the lights identify the problem.
Light Pattern
Problem Description
Suggested Resolution
The computer is in a normal condition or a possible pre-POST failure has occurred.
See System Lights.
The computer is in recovery mode.
None.
A possible processor failure was detected.
Contact Dell. For information about contacting Dell, see your Owner's Manual.
Memory modules are detected, but a memory failure has occurred.
- If you have two or more memory modules installed, remove the modules, reinstall one module (see Memory), and then restart the computer. If the computer starts normally, reinstall an additional module. Continue until you have identified a faulty module or reinstalled all modules without error.
- If available, install properly working memory of the same type into your computer (see Memory).
- If the problem persists, contact Dell. For information about contacting Dell, see your Owner's Manual.
A possible graphics failure has occurred.
If the problem persists, contact Dell. For information about contacting Dell, see your Owner's Manual.
A possible floppy drive or hard drive failure has occurred.
Reseat all power and data cables and restart the computer.
A possible USB failure has occurred.
Reinstall all USB devices, check cable connections, and then restart the computer.
No memory modules are detected.
- If you have two or more memory modules installed, remove the modules, reinstall one module (see Memory), and then restart the computer. If the computer starts normally, reinstall an additional module. Continue until you have identified a faulty module or reinstalled all modules without error.
- If available, install properly working memory of the same type into your computer (see Memory).
- If the problem persists, contact Dell. For information about contacting Dell, see your Owner's Manual.
Memory modules are detected, but a memory configuration or compatibility error exists.
- Ensure that no special memory module/memory connector placement requirements exist (see Memory).
- Verify that the memory modules that you are installing are compatible with your computer (see Memory).
- If the problem persists, contact Dell. For information about contacting Dell, see your Owner's Manual.
A possible expansion card failure has occurred.
- Determine whether a conflict exists by removing a card and restarting the computer (see Cards).
- If the problem persists, reinstall the card that you removed, remove a different card, and then restart the computer.
- Repeat this process for each card. If the computer starts normally, troubleshoot the last card removed from the computer for resource conflicts.
- If the problem persists, contact Dell. For information about contacting Dell, see your Owner's Manual.
Routine system activity subsequent to video initialization.
Watch your monitor for on-screen messages.
System resource configuration in progress.
None.
System board failure has occurred.
Contact Dell. For information about contacting Dell, see your Owner's Manual.
During normal operation, all of the diagnostic lights turn on and then turn off before the system starts.
NOTE: If all of the diagnostic lights are on and the system does not start, there may be a problem with the power supply or with the processor.
If the system does not start, plug the computer into a working electrical outlet. Also see System Lights.
If there are no power problems and the system does not start, contact Dell. For information about contacting Dell, see your Owner's Manual.
Beep Codes
Your computer might emit a series of beeps during start-up if the monitor cannot display errors or problems. This series of beeps, called a beep code, identifies a problem. One possible beep code consists of one long beep and then two short beeps. This beep code tells you that the computer encountered a memory test failure.
If your computer beeps during start-up:
- Write down the beep code on the Diagnostics Checklist. The Diagnostics Checklist is located in your Owner's Manual.
- Run the Dell Diagnostics to identify a more serious cause. See Dell Diagnostics.
- Contact Dell for technical assistance. For information about contacting Dell, see your Owner's Manual.
Code
Cause
2 short, 1 long
BIOS checksum error
1 long, 2 short
Memory test failure (bad memory during memory sizing)
1 long, 3 short, 2 short
No memory
1 short
F12 key pressed
330
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Posted August 4th, 2011 07:00
Sorry C521 No beep codes. Same action as before except that only that diagnostic light 1 comes on for a haft second
330
1
Posted August 4th, 2011 09:00
Do any lights stay on? Starting to sound like a power supply issue.
330
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Posted August 4th, 2011 10:00
When I disconnect motherboard from power supply and leave the power connect to DVD I can open the disk door with the reject button. his even though all diagnostic are off.
I checked the power supply by jumping the green and black wires on the main mother board connector and all the voltages were correct. .
330
1
Posted August 4th, 2011 10:00
A cdrom is not a sufficient load on the power supply.
So it could be a Bad CPU or Bad Motherboard but it could also be a Bad Power supply.
Testing with a known good Power supply would be the next thing I would try.
330
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Posted August 4th, 2011 10:00
Forgot to answer your question = No lights on
oldjay87
7 Posts
330
1
Posted August 4th, 2011 11:00
Wired a large working 400 watt power supply to the mother board the the same result. I am ordering anew mother board.