# Dell Latitude C640 won't boot - blinking caps lock LED



## jeffbrig (Feb 14, 2005)

Yesterday the laptop wouldn't start. Starts to power on, caps lock LED blinks repeatedly, then shuts off. I have no doubt this is a POST code, but I can't find any info from dell to determine it's meaning.

After pulling power, battery, etc. and waiting a while, we got it to boot to windows, then got a BSOD with an error message and had to turn it off. Back to the post code.

I connected the drive to my desktop and backed up all the data. Then I stripped the laptop down the system board (no obvious hardware problems detected), then tried to power up with memory and CPU only. Seems to work, tells me no HD found (as expected). I added the HD, and made it to windows startup screen, saw the desktop, then it hit a BSOD.

I tried another reboot, and went into the bios, turned on "thorough POST". On the next power cycle, no POST errors, but I hit F12 to go to Diagnostics. First time through, it hung in a memory test. Not sure that's the culprit, I rebooted and did it again. Made it through the memory test no problem, next step it loads a diagnostics GUI. Started running system board tests through the GUI, and it locked up again.

Next reboot and I'm staring at the blinking caps lock LED again, and can't get it to boot. This is with AC power, and only the keybaord, CPU, HD, and memory installed. Since then, I haven't been able to get it to boot successfully.

I am completely comfortable taking this thing apart and replacing things, but until I can determine what the POST code means, I don't know where to start. System board? Power up circuit? Who knows?

-Jeff


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## buddythedog (Feb 18, 2005)

Memory, system board or CPU. 
Try reseating the memory. Supposedly there was one model where the CPU would come loose and cause this problem also. 
Once you get beyond the above I don't know any good way to sort out what the problem is short of replacing parts which obviously get expensive.


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## jeffbrig (Feb 14, 2005)

We've already removed and reseated the memory a couple of times, made no difference. I'm looking at salvage system board and CPU combos right now on Ebay, and they're running $150-$200. I might go for one, but I'd like to be pretty sure it won't be money wasted....


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## borislanger (Jul 24, 2007)

I had the same behavior on a Dell D630 laptop. This started happening when We tried to expand the default 1 Gb of RAm and add another 2 GB DIMM. For some reason it didnt like having the larger DIMM in slot B, and we had to swap them.
IT's a little tricky to get under the keyboard, but doable. I recommed searching for the repair manual on Dell's support site.


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## jeffbrig (Feb 14, 2005)

We gave up on this laptop months ago. I bought a 'working' shell of the same laptop on Ebay, and we were able to swap MBs, memory, CPU, etc. Got it to boot once or twice, then it went into the same problem.

No thanks, return to sender. Bought a new one, and haven't looked back.


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## oohay_7777 (Jul 31, 2007)

Hi Jeffbrig,

I am facing teh exact same issue and now have to backup the hard disk. Could you please explain how you managed to connect the drive to your desktop and backed up all the data?

Did you use some special connector cable?

Thanks.


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## jeffbrig (Feb 14, 2005)

Something like this, I bought one locally at a computer store.

Laptop to IDE drive adapter:
http://www.cablestogo.com/product.asp?cat_id=906&sku=17705
(my apologies if this violates the site's commercial policies)


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## oohay_7777 (Jul 31, 2007)

thanks, that helped


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