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Blank Screen at Computer Startup (no mouse or keyboard either) Fans and HD run.

When I plug my computer in and hit the tower power button, the fans and the hard drive fire up, but nothing happens on the screen (it's blank) and the monitor's power led flashes yellow on and off. The usb wireless mouse receiver doesn't light up nor does my (wired) keyboard num, caps, and scroll lock light up. What is going on?

I have tried switching monitors as well as confirming that the monitor connector is firmly attached. When I detach the monitor, the 'check signal box' comes up on the screen.

I have a Dell Dimension B100

I just returned from vacation and my computer worked fine when I left.

I hope you all can help.
Fred
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flove101
Asked:
flove101
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5 Solutions
 
mjcoyneCommented:
There are no BIOS beeps?  You can try clearing your CMOS to reset your BIOS, and see if that resolves it.  I would suspect your video card died, but it's curious that your keyboard and USB mouse are also affected.  Perhaps while you were gone, your computer got zapped by a power surge?  Was it running?

Open the case and check to make sure your CPU fan is still running.
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CallandorCommented:
You'll have to take the machine apart to isolate the cause of the problem.  Not being able to boot could be due to:
- motherboard shorting on case, or dust accumulation
- bad/loose connections
- extra power connector not attached to motherboard
- faulty or inadequate power supply
- bad RAM, or wrong ones for your motherboard, or bad RAM slot (try in another slot)
- faulty video card
- bad motherboard
- bad cpu

Take the motherboard out of the case and put it on a nonconducting surface, like wood or a cardboard box.
Install one module of RAM, the cpu, and the video card, and reset the BIOS after installing the cpu.  Do not include hard disks, other PCI cards, or other peripherals.  See if it boots, and add more components if it does.  If it doesn't, get a hold of compatible RAM that you know works from another machine and install it.  After that, try another video card, and then power supply.  If it still doesn't work, you may need to decide between the cpu or motherboard; though motherboards are more likely to fail than cpus.
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ClickCentricCommented:
Does the hard drive light show activity like the drive is booting up?
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jamietonerCommented:
on the back of the system there are 4 diagnostic leds (marked a,b,c,d) what colors are they?
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Jbirk1Commented:
Hi,

I have to replace over 40 Dell motherboards due to leaking capacitors.

Check to see if the capacitors are bulging.  If they are, replace the motherboard and it will fire right up.

As for the case, it won't be shorting to the case.  There is a tray and the motherboard is built in such a way to where it would be impossible to short.

My advice.

1.  Check the capactors.
2.  Blow off all the dust.
3.  Reset the CMOS (jumper is usually near the ATX connector).  Typically, the jumper covers password and CMOS Clear is open.  If you remove the jumper and boot it removes the password.  If you remove the jumper then move it to the other jumper then leave it for a moment then move it back, you you reset CMOS.

You can also do this by pressing F2 to get into setup and turning on Num Lock, Caps Lock, and Scroll Lock then pressing and holding ALT E, Alt F, Alt B in a sequence.  The first resets NVRAM and PnP settings, the seconds resets all setup options to factory, and alt b saves and reboots.

I cannot find a B100 in the documentation.

Find something that looks like your computer:
http://support.dell.com/support/systemsinfo/documentation.aspx?c=us&l=en&s=gen&~cat=12&~subcat=84

Also, check http://support.dell.com to see if you are covered by warranty.  Just type in your service tag and select "Services and Warranties" from the drop dwon.


If the system does not boot and does not having bulging capacitors, troubleshoot.

There is no need to remove the motherboard because it won't be shorting.  Don't touch the CPU or cooler because it is already properly mounted.  If you have a video card and memory, remove all of them and put them all back in to reseat them.

Try again.


If that does not work, look up the Dell Diagnostic lights on back.  Dell does not use beep codes most of the time.  They have them, but they are rare.

Most of the time, you get LED codes on back, which are great.  There will most likely be lights A, B, C, and D.

http://support.dell.com/support/edocs/systems/dim8300/sm/adtshoot.htm
http://support.dell.com/support/edocs/systems/dim5150/sm/tshoot0.htm#wp1114195

You may have to find your computer, but those charts are common really to most dimmensions.  It will usually be one type or the other.

Other things that happen to Dell computers:

*.  Reset your monitor to factory.  Very rarely I have seen Dell Monitors not work until reset to factory.

*.  Connect your monitor to the integrated video instead of a video card.  Sometimes teh bios gets configured and doesn't automatically use a video card.  Hence, no video.

Bare Bones Troubleshooting.

1.  Just leave the motherboard in the case.  It won't be shorting, so no worries here.  Dust it off though with a can of compressed air.

2.  Remove expansion riser if you have one and all PCI cards with it and all other epansion cards.  

3.  Remove all ram excpet for one stick in the first slot.

4.  Leave the CPU (pentium 4 and heatsink) alone becuase it has about a 1 in 5000 chance if even that of being bad.  It should be fine.

5.  Remove the video card and attach your monitor to the integrated video.

6.  Disconnect all IDE and floppy cables as well as any SATA cables.

7.  Only a monitor and keyboard connected at this point.


If you cannot get the system to do a Power On Self Test, make sure the monitor is good.  If you still get nothing, try the other stick of ram and expect to still get nothing.

At this point, you need a motherboard, Power Supply, or CPU.  Chances are very good if you make it this far and the fans are spinning but nothing is booting, you almost certianly need a replacement motherboard.


********

Once you get your comptuer fixed, put it all back together.

Remember RAM is Dual Channel in most modern Dell computers.  There are usually white, grey, or black RAM holders.  Be sure to put one stick in each of the white slots...  Just put it back how you got it out in other words.  Do not put the memory in 1 and 2 in most cases.  Usually Dell does slots 1 and 3 for memory.  Unless you number like 1324.  Essentially that is common with colors being White, Black, White Black.  Fill the white slots in that case.


Justin
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flove101Author Commented:
Wow. I'm telling you what. Your help is definately worth the premium fee. Let's see if I can clarify a few things.

mjcoyne  -  No bios beeps on startup. Strange thing was that the tower was unplugged the duration my trip but my monitor was plugged in. There was a storm while I was away (machines at work went offline due to thunderstorm). I have taken the cover off and the CPU fan is running.
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flove101Author Commented:
Callandor:

I was amazed to see how much dust was inside. They weren't classified as bunnies, but perhaps small dogs. I guess a trip to wally world for the compressed air is in order.

It all worked for months before. It doesn't seem like a compatibility issue on the hardware end would be the culprit. I do think that something could have gone bad over the break.

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flove101Author Commented:
ClickCentric:

I can hear the drive start and the light flashes indicating activity.
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ClickCentricCommented:
You may want to pick up a cheap graphics card and test it (can always return it if you want a better one and/or it doesn't fix the problem)...if the monitor was plugged into power and the monitor was plugged into the tower, it very well could have fried the onboard video if a bad storm came through.  Usually you can see or smell the burn...but with as much dust as you're talking about, it would be hard to identify.  If the hard drive light is showing normal boot activity, it seems likely that the computer is continuing as normal and that the video is the center of the problem.  This is assuming, of course, that you're out of warranty...if not, then make dell fix it for you.
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flove101Author Commented:
ClickCentric:

Update: The light only flashes once when I first start it. I don't know if that's of signifcance.
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flove101Author Commented:
I am out of warranty. Hey ClickCentric, thanks for the super fast response.
I'm just trying to make it down the line of solutions...
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flove101Author Commented:
Jamietoner:

A and B are Orange and C and D are Green.
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flove101Author Commented:
UPDATE::::

I found the diagnostic codes for dell (via post) and it says that there is a memory failure. The solution to that is to remove one and see if it will work. I'm going to give that a go.
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jamietonerCommented:
just post the results of try 1 stick of ram at a time, sounds like 1 of the sticks maybe bad
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flove101Author Commented:
UPDATE 2 !!!!


Well, Long story short, I blew out the dust and removed the ram and tried the different combos ( my ram comes in pairs) and got the bios beeps and basically put the ram in exactly the way it was in the first place, and it worked.

I'd be interested in knowing why I had to take out and reseat the ram for it to work....
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mjcoyneCommented:
Excellent, flove101 -- congratulations.  Quite a little detective story, huh?
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CallandorCommented:
>I'd be interested in knowing why I had to take out and reseat the ram for it to work....

Oxidation on the contacts, perhaps?  Thermal expansion/shrinkage and loss of conductivity?
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ClickCentricCommented:
Dust can wreak havoc if it's made of something conductive.  Many times simply taking memory out, blowing it off and putting it back in has been the solution to a problem.  For techs researching such a problem in which there wasn't a clear indication of cause, usually the first step would be to disassemble the system, clean it and put it back together.  You'd be amazed how often that alone resolves problems.  
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Jbirk1Commented:
I have seen this happen before on Dell computers twice where they wouldn't boot and I just reseated everything and they booted.

I have also had one time when I replaced a motherboard and it started beeping at me.   Reseating the memory fixed this.
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