I have a Dell Latitude C640 laptop. It shuts off all the time and can usually only get windows loaded and it’ll shut right off
Hi, I have a Dell Latitude C640. It shuts off all the time and can usually only get windows loaded and it’ll shut right off, then it will turn on and turn off right away at boot. I’m very familiar with taking these apart and when this first occurred I suspected a clogged cooling system. So I checked, and it was clean as a whistle… hmmmm…so I’ve been looking for anything out of the ordinary on the motherboard but everything is tight and looks clean. Even took the LCD apart to make sure there weren’t any loose connections. So if you could give me any insight on this it would be a great help! The only thing that “SOUNDS” suspicious to me, is that sometimes I can HEAR the power when I plug it in, a very faint high pitch ringing noise…. so then I figured well if its the plug technically it should still run fine off the battery, but it does the exact same thing. I’m also suspecting that maybe my fans aren’t running fast enough?? Or maybe I need some new thermal grease on the CPU??? HELP!!
Yeah, looks like an overheating problem. By the way, have you checked if the fan spins at all? May be it stuck and causing this high pitch noise?
I would probably remove the hard drive and boot the laptop from a Knoppix CD. Knoppix is a live Linux CD and it will boot your laptop to a Windows like environment. You don’t need the hard drive to boot the laptop with Knoppix, only the DVD/CD drive. If the laptop boots fine and doesn’t shutdown, then something is wrong with the hard drive or with the operating system on it.
Also I would test the memory module. You can run Memtest 86+ and see if the memory fails the test. It’s possible, that the memory works fine for a while when it’s cold, as soon as it warm up it fails. That’s why your laptop works fine for some time, and then just shuts down when you restart it. If the laptop doesn’t run long enough to finish up the memory test, then try to replace the memory if you can find any test module.
Of course, I would try to reseat all connectors inside the laptop. Any loose connection might cause this problem.
February 16th, 2008 at 6:32 pm
I had the same sudden shut down symptom at my C640 laptop. I tried the “cheap” solution indicated in this forum, namely to increase the mechanical pressure over the memory modules by adding some thin rubber over the modules. The computer, which I was going to throw away, works fine since then. Thank you!
February 4th, 2008 at 10:58 pm
Missy,
Here’s the service manual for your laptop. It looks like you can access the fan if you remove the keyboard, it’s not very clear. If not, you’ll have to remove the top cover.
This service manual has step-by-step disassembly instructions.
February 2nd, 2008 at 12:21 pm
Hello
lol
MISSY XXX
Can you help me out please
I want to remove the dust from the heatsink of a Dell Latitude C640 but I don’t know where it is located.
Do you have to remove the keyboard and everything or is there a little door just for the heatsink
I know I gotta ground myself and remove the battery before to operate but that’s it
I’ll try this because I have #M1004 Error Code.
Thanks a lot for your answer
January 31st, 2008 at 8:29 am
I’ve got a C640 1.7GHz/512RAM. I don’t know its history since I got it used for free, but the thing works great and I leave it on all day. It does like to run its fan a lot more than my Compaq Evo N620c does, but it never dies unexpectedly. The one weird thing it does is that the touchpad will randomly freeze up on occasion (everything else is still fine).
And to the person who asked about the amber/green flashing light, that generally indicates a battery failure.
January 23rd, 2008 at 3:50 pm
I have a DELL C640 the same problems just keep shuts off
but I’ve just found a simple experiment i use an external monitor and plug it to my C640 laptop and turn the laptop on the computer boots and runs great with the external monitor. This could be a good and quick check for the CPU, Fan and the memory but i am still working on WHY? the laptop works only when there is an external monitor plugged in to it and why not with it’s built LCD screen. Please if someone out there knows how to deal with this issue please POST
Muruts
January 8th, 2008 at 10:53 pm
I’ve read all the problems people have been having, and many of them look like the problem I’ve had with my Dell Latitude D600. Just like “Laptop Freak” and “Steve,” what I found was if I roll up some cotton gauze about the length of the memory stick and put it on top of the stick, then screw down the hatch, the pressure anchors the ram stick in place and prevents the weird random shutdowns. It was clearly a loose connection between the memory slot and the mobo: when it was working, if I simply tilted the laptop over onto one side or the other, it froze immediately. Now I can move it all around upside down, sideways, etc., and no freezeup. I imagine a good laptop or mobo repair technician could identify where the loose connection is–probably a solder joint has come apart–and resolder it solid again.
Jonathan
November 25th, 2007 at 2:10 am
I bought a used Dell C640 not working condition with no hard drive When I turn it on (using the AC adapter)it goes on for seconds and then shuts off I notice the chassis fan doesn’t spin but then when would it since the unit doesn’t stay powered up long enough to make a judgement re the fan So where should I start?
November 20th, 2007 at 12:11 pm
I took some photos of how i fixed my laptop. hope this will help anyone else who might run into this problem.
November 20th, 2007 at 12:21 am
Success!!!!!!! I cut up an eraser lengthwise and placed it on top of the RAM sticks and then screwed the cover back on. So far so good! No problems and lets hope it stays this way! Thank you for the all the help guys! You’re all the very best!!
November 17th, 2007 at 11:53 am
Steve,
Find a known good RAM module. Test the laptop with this module in both slots. First, install the module into the slot 1 and run it for a while, then do the same with the slot 2. Find out if the laptop freezes with your known good memory module, find out witch slot is bad. If the memory slot is bad, most likely you’ll have to replace the whole motherboard or use the laptop with one working slot.
I have the same problem with one of my IBM ThinkPad notebooks. One of the slots is bad and the laptop cannot see RAM module installed into this slot. I was able to fix the problem by placing a small piece of pen eraser on the RAM module installed into the bad slot. When you close the RAM hatch, it presses on the eraser and the eraser applies pressure on the RAM module installed into the defective slot. It was enough to make a good connection between the memory and motherboard. It’s just a temporary fix but it worked for me.
November 15th, 2007 at 11:24 pm
this is also explain in this post :
http://www.hardwareanalysis.com/content/topic/50498/?o=20#494540
November 15th, 2007 at 8:43 pm
hi,
i upload two low-res pics (sorry) :
http://img263.imageshack.us/img263/5717/spa0054za5.jpg
http://img180.imageshack.us/img180/2716/spa0057uo7.jpg
that’s still not the best solution : i haven’t time to do it for good, and this freaky tip could (maybe) create an overheating (?). I think about build something more clean. but that’s work fine ! Don’t forget to hardly close the back-door.
bye, had
November 15th, 2007 at 12:20 pm
hey there had.
I suspect there is something wrong with the RAM disconnecting and connecting too. I’ve taken the laptop apart and tested each component and there is nothing wrong with any of the peripherals etc. I still suspect something wrong with the RAM connectors because when I swap the RAM from one slot over to the other the laptop works fine. For a while till it freezes up again. Is there an overheating issue in the RAM area at the bottom of the computer perhaps? And could you explain a bit more or do you have a photo of the biz card cut into 8 pieces solution which u have used? cheers m8
November 14th, 2007 at 1:38 pm
i’ve the same problem with my dell C640. the soluce is really simple : the ram disconnect from the JDIM(1or2)
each time you move your laptop. To solve this problem use one of your biz’card, cut it in 8 pieces, and stuck them over the ram. no joke.
bye, had
November 9th, 2007 at 5:02 am
Hi,
on may 20th I wrote
“…perhaps, after many experiments (look at my previous posts), I’ve solved my Dell power-off problem…”
but I was not right, ’cause after one month the problem was again.
Finally I changed the MotherBoard (keeping all the rest) and this – as I expected – solved the problem for real.
Again, I think that most of these power-off problems are a MB issue.
Gico
November 8th, 2007 at 9:19 pm
Steve,
In order to narrow down the problem you’ll have to take this Latitude C640 laptop apart piece by piece and test it after each removed part.
1. Remove the battery and test with the AC adapter. I’ve seen bad batteries freezing the whole system.
2. Remove the wireless card, test again.
3. Remove the modem card, test again.
4. Remove the DVD drive, test.
5. Unplug the keyboard from the motherboard, test.
6. Remove the hard drive and see if the laptop freezes in the setup menu.
7. Unplug the display assembly and test with an external monitor.
In short, find out witch component is freezing the system. If the laptop stops freezing after you remove the wireless card, most likely this is the problem.
Finally, after you remove all components, you’ll have only three major parts: motherboard, processor and memory (I assume a good one). If the laptop is still freezes when you test it with an external monitor, I would assume that you have a problem with the motherboard. CPU failures are not very common and we assume the RAM module is good, so there must be something wrong with the motherboard.
November 8th, 2007 at 2:19 pm
Wow I guess I’m not alone in this dilema! Ok I have a Dell C640 with the A10 BIOS update. Gotta admit that this laptop is a workhorse and has provided more than 2 years of service and I use my laptop @ work and and at home. The only time it is off is when I am sleeping! But alas my poor Latitude C640 is running into problems now. I cam across this forum and thought I’d throw my problem out to the rest of ya and see what you might have to say.
Ok so about 3 months ago I was working away merrily in Windows and my laptop froze. No bigge.. just tought all I need to do was reboot and I’d be back in business. Fat chance. Every time I tried booting up I would get the CAPS LOCK key flashing 10 times and then I would hear a whipering noise from the laptop and then nothing. Literally nothing comes up on the screen. Nothing boots up. I don’t even see the Dell logo. Nothing.
First thing I did was to extract my hard drive and move all my essential data to my desktop. All the data was there. Everything is in tack so that rules out any hard drive malfunction. I then reinstalled the hard drive and also decided move the RAM chips. So I opened up the bottom where the RAM is located and I swapped places with the RAM. Switching their slots. Lo and behold everything worked!
Till today that is. Back to a dead laptop. Now I know that the hard drive is workin. I’ve rebooted a number of times and I was finally able to get it to boot up and go into windows. But it froze up. Then it wouldn’t boot up again after several tries. I reseated the RAM and it still woulnd’t boot up. After trying several times I was able to get it to reboot and am at this very moment running Memtest86. The RAM seems to be ok as the Memtest has not found any errors in the RAM. So does anyone know what I should do next? I should also point out that the laptop has been running this memtest for the past 60+ minutes and the computer still hasn’t froze. Which to me is a surprise because the laptop will sometimes freeze even in the middle of booting up. Heck it sometimes even freezes while loading the BIOS. I was able to log into Windows XP last night and it was wroking fine for about 10 minutes till it froze again. So I’m quite certain that the OS is fine. Perhaps it is a hardware failure? Motherboard fault? BIOS? Any ideas or has anyone else come across this problem too?
October 16th, 2007 at 2:13 pm
Take an EGA or VGA monitor and connect it to the adaptor, the machine should
stay running. If it does not then your fan is not running on the laptop.
I have removed the screen and attached wheels. The system runs fine until
it hits a wall. Also you sometimes need to press on the hard drive daddy.
I have exchanged the Hard drive for a CF card (50.0) and an CF laptop
(19.00) adaptor. There are no moving parts except the wheels.
Adam
October 16th, 2007 at 1:09 pm
My C640 just started crashing with any RAM inserted in the second DIMM slot. I traded several different modules and it always crashes when the second DIMM is populated.
Has anyone seen a similar situation? Is there a fix other than replacing the motherboard?
Thanks.
October 15th, 2007 at 6:16 pm
Dell C640, same random power off problems. After sitting for a bit, it will run for about 10-15mins, after that not very long until sitting for a bit.
May have to unplug the power adapter to get it to start again and / or the battery. Does the same thing under battery or wall power. The power LED sometimes does the following after hitting the power button.
Amber Green Green Green Amber
What does this code mean?
ort11 @ execpc.com
How many others are seeing this?
October 2nd, 2007 at 4:11 pm
I have a Dell Latitude D233SD. I am running XP PRO. CF Card Ram for a harddrive.
1) If the four lights come on and not HD light. Press down the CPU and the power module on the laptop. It will then boot.
2) If HD light but runs for 35 seconds place Display adapter in external video adapter and Motherboard will stay running.
3) CPU heat problem, replace fan.
Does anyone know how to get the motherboard to run without LCD and external display? Is this an XP Pro and NeoMagic settings problem?
July 28th, 2007 at 2:18 pm
Rennie,
First of all, I would check the memory. Reinsert the memory module/modules and test the laptop again. Test it with a known good memory modules. It might help.
July 27th, 2007 at 7:41 am
Hi, my problem is even worst, my dell C640 works fine once started but after you shutdown the laptop overnight the next day it may not start. What I notice is the power light will come on when press and that’s it. The power light will just stay on, you have to remove the battery and AC connection for it to go off and even when you reinsert the battery and plug in the AC adaptor only the power light will come on and that’s it.
The only way the laptop might come on again is if you remove the battery and AC for a long time, very frustrating. Have any one solve this problem ?
July 25th, 2007 at 5:31 am
My battery is fine, the laptop is cool and the fan spins. After the windows logo and the loading bar pass a blue screen quickly flashes up then dissapears then reboots. I can’t seem to stop this. I am very annoyed as it is a new laptop and i’m not sure what to do. Neither can I hear a problem. Can anyone help?
Regards,
S Chittenden
July 24th, 2007 at 2:00 am
Hi,
I have the same problem with my dell latitude.
I was working on it that it suddenly off (on battery).
I tried to start it again it started and on windows startup it was off agian.
I thought it was coz of a low battery. Again i plugged in the power and started it, it asked that want to start windows normaly, after i press enter, windows started loding and it agian went off. After that it has never come on at all. But sometimes its LEDs lit for a split second as I push the power button. Hi what could be the problem, how to fix it. I hear a very very low sound on pluging the power, as i move very close to the plug socket… What could be the problem.
is it with the MB
Regards,
Shehzad
July 16th, 2007 at 8:16 am
I have a Latitude C640 it shut off right at booting. It happend a few days back all of a sudden it just shut off and from then on it does not start up at all. Are there any tests I can do to narrow down the problem any help would be great…….
Regards
Jay
July 12th, 2007 at 7:24 am
Sorry; my previous post left off holding down the blue FN key to boot into the system diagnostics.
July 12th, 2007 at 7:21 am
Dell has 2 tiers of built in diagnostics that may be helpful to some of you. When the PC first powers up hitting the F2 key will take you into the BIOS setup screen, F12 allows several other booting options (for example, booting from the CD). Also listed under the F12 option is “Diagnostics”. Select this to run either an abbreviated system diagnosis (running from the system board), or, when that gets done, a MUCH more complete diagnostic, that runs from the hidden hard drive partition. In this 2nd diagnostic, you can run tests on individual components (I know the fan is one option).
An alternative means of getting to the diagnostics is to hold down the blue (purple?) key (lower right of the keyboard) as the system boots up. I hope this can be of some help to those of you experiencing problems out there.
May 28th, 2007 at 7:20 am
I have a similar issue with my Dell C640, but slightly different. My laptop works fine on Battery power but it will not charge or run on AC power. I have dis-assembled the laptop, cleaned the board with canned air(attached my electro static discharge cable too). I re-assembled the laptop and plugged it in, it still does not recognize the Power Supply. I have purchased 3 brand new power supplies, and tested them on another Dell laptop( I love Dell). I still cannot get the laptop to run or charge on AC. Can anyone help me out here? Thanks.
Jerry
aka Vampnite69
May 20th, 2007 at 11:07 pm
Hi,
perhaps, after many experiments (look at my previous posts), I’ve solved my Dell power-off problem, but don’t know how!
After months of inactivity (I had decided it was gone forever), I reassembled the laptop (I made my experiments using the naked motherboard) ’cause I decided to sell it as “not working”. Anyway, before reassembling it, I checked for the last time: it was really gone.
My laptop had been always missing of the screws on the back, those used for connecting monitor, serial cable and parallel cable. Perhaps they were lost, or remained attached to the connectors in some office.
This time I found some screws that could fit and used them.
I completed the job and, once again, I switched it on, and that’s the MIRACLE!
Now it works PERFECTLY! I’ve been using it ten hours a day (for job) for a week.
What can I think? Perhaps screws keep motherboard in a particular position or create a mechanical tension/torsion on it, making it to work.
This could mean that the problem (in this case) is a faulty welding or something similar.
Perhaps my laptop will turn-off in five minutes. I hope it will not. I’ll let you know.
Hope my eperience will help someone.
Ciao
Gico