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.
April 5th, 2009 at 1:06 am
Hi there BDOG
It is difficult to say what the normal runing temp is , because it all to do with CPU/dvd/gaphics usage , useually the fan cuts in at around the 50 to 60c , when you say heats up i am not sure what you mean , heats up to what temp !! .
have you got fangui loaded !! , ( this is a programe to control the temp ) better than dells bios , if you have not e.mail me and i will sen you the programe .
stanley.binns AT ntlworld.com
cheers
spike
April 1st, 2009 at 4:44 pm
I have a dell c640 laptop and was wondering does any one know the normal running temp that these computer should run at before it will crash or burn up components? Also i have had the same problems of having the computer crash all the time and i replaced the processor and now seems to be running good but still heats up but it wont crash.
February 19th, 2009 at 2:27 am
So the C640 was freezing when using JDIM2 . I would get the blinking caps light and some HD noise but then would turn off. The very few times I actually got it to boot, it would simply freeze within a minute.
I used a piece of formed plastic about 3/4 the size of ram chip. The formed bubble on the plastic put extra pressure down on the chip. It worked immediately. Hats off to HAD!
February 4th, 2009 at 7:22 pm
I have had my C840 laptop soldered to replace the U28 chip which is NE of the SMC chip on the left side of the board, under the CD-ROM slot (a bit different to the C600 and C640). I am little bit happy to say that it seems slightly better. I reinstalled XP, but it still freezes, especially if bumped or knocked. DIMM A slot still doesnt work, but I have been using the RAM pressure trick to angle the stick so it sits in the slot differently. I have also tried cleaning the RAM dimms contacts with a pencil eraser (but not the mobo pins). This makes it seem a bit better (will run for longer without freezing up). I did find that running it with a 60W power supply instead of the 90W (hence a slower CPU clock speed) seemed to help, and battery seemed to be even better. I had it in a C-Docking station all night and day and it was still running, but when moved out of the dock it froze up. I think that the 6 year old, abused laptop is terminal and should be retired.
January 2nd, 2009 at 4:01 am
Does anyone know if this will do the job? or this as i can not get the fairchild ones in the uk.
January 1st, 2009 at 3:27 pm
Scopio i could do with a couple of those chips if the mods allow you can contact me by email @ bilko2001(at)hotmail.com change the (at) to @ obviously:)
December 9th, 2008 at 4:07 am
Hello,
Pressing memory method was working for me too.
Thank you every body.
November 30th, 2008 at 3:06 pm
Thank you everyone for you help and thanks to you I’ve fixed my lappy !!!!!!!!!!!! Dell C640 -U45 shut down after 2 mins problem.
I tracked down some of the FM809SS3X devices, they are hard to see & hard to get a soldering iron on each little pin.
I’ve never soldered before so I looked up a few you tube clips on the technique, practised on some old bit of wire, stripped the lappy ( struggled a bit but it was not working so what the hell )
Anyway now been running it for two spells of 5 hours each and its great. I think I was a bit lucky as I the solder didn’t look text book. ( I used a magnifying glass to see thins more clearly if it helps anyone)
I’ve some FM809SS3X devices for sale but I don’t think you can give details on this site.
If anyone is interested I could pop them on ebay. ( Mod is this ok )
Scopio ( UK )
November 23rd, 2008 at 10:44 am
I guess that’d be one of these:
http://www.fairchildsemi.com/pf/FD/FDS6675.html
Sounds like a different problem to the U45 (both symptoms and component), but perhaps worth trying to replace it.
IanC
November 21st, 2008 at 10:20 am
Hi,
Can anybody help? My Dell C640 seems to be short circuiting. Please see photo below.
http://i140.photobucket.com/albums/r20/norm360/dell_c640_q2.jpg
When I plug the AC adapter in this component gets *very* hot to the touch and emits a small ticking sound. The LED on the power brick also flashes on and off. The laptop will also not run from a fully charged battery.
Here’s what I think is written on top of the chip,
F P238L
FDS
6675
The 8 could be a B however.
I’m not sure if it’s related to the U45 component fault or not.
Please advise.
Thanks
November 18th, 2008 at 9:47 am
AIUI that resistor is an alternate way of getting the machine to work, but it creates some sort of slow startup/switch off issue.
If you replace the U28 device (and it was faulty) you should be OK without the resistor.
IanC
November 17th, 2008 at 6:00 am
OK!
I am getting good at tearing the C840 down to the mobo. I stripped back the black sticky to get to the SMSC chip and had a look around for a three pronged IC Chip. There is one directly diagonal NE (towards the back of the mobo) with U28 with 2 prongs on the north side and one in the middle on the south.
Here are some pics
http://img80.imageshack.us/img80/3544/c840moboyz1.jpg
http://img80.imageshack.us/img80/134/c840revealnc6.jpg
http://img300.imageshack.us/img300/3293/u28jh0.jpg
Ok now I know the part I am going to take it to get soldered. One thing I am unsure of is if it needs a resistor. I found a Polish forum with a pic that I have stolen for everyone. Sorry for stealing your pic.
http://img88.imageshack.us/img88/7093/4ca9c95f287399b1medod3.jpg
Cheers all.
November 16th, 2008 at 5:25 pm
Hi Everyone;
First… let me thank everyone for their help and replies. But… I could use some additional help!!
I 10 of the FM809SS3X devices from Newark and have replaced the device. (Man that’s one little sucker — hard to see, hard to get a soldering iron on each little pin!!)
Anyway… now the laptop does nothing — no green led when powered on from battery, nothing when I plug the AC adapter in.
I am wondering if I overheated the FM809SS3X when soldering the new one in place (I have spares to try again if need be).
Are there some voltages I can check to make sure I did the job right?
Does anyone have a schematic or service manual to assist in repairing this thing?
TIA.
November 12th, 2008 at 5:26 pm
To clarify my last post…
The SMSC and U67/U45 device are in the same position relative to each other on the C600 and C640, but they appear in somewhat different locations on the motherboards for the two models. Finding the large package on a ‘new’ type of mobo hopefully makes it easier to locate the smaller one.
BTW, just actually fixed a C640 by taking the U67 from a scrap C600 mobo to replace a presumably duff U45. Fiddliest bit of soldering I’ve ever done, but a pleasing result. Thanks to everyone who provided the info.
IanC
November 12th, 2008 at 12:44 pm
For Lau See Ping…
On both the C600 and C640 the device that fails is just above the ‘M’ of a square package with SMsC written on it that is about 15mm square, as seen in the picture that is linked to above.
If you can see an SMSC package on the C840 then take a look in the same place. On the C640 this is U45, on the C600 it is U67.
IanC
November 11th, 2008 at 2:56 pm
For C840 owners,
I have been following this thread because I have a Lattitude C840 which has similar problems to everyone elses C640s. I tore it down to find the U45 and found an empty location near the battery/floppy connection with U45 printed near it. So it looks like for C840′s there is a different IC that might need replacing.
Cheers
November 8th, 2008 at 7:32 pm
“For those of you wondering about the actual location of U45 on the mobo, here is a pic:
http://i7.photobucket.com/albums/y285/Jungesblut/Stuff/U45.jpg
It is the little 3-contact IC between the “large” PCIbus & SMSC ICs.”
November 8th, 2008 at 4:50 pm
Hi IanC;
Thank you for the reply and info — I see it now.
From my description of the problem and what I’ve already done, do you think this is the component that needs to be replaced?
BTW — does anyone have a schematic and/or troubleshooting manul for a Dell C640?
TIA.
November 8th, 2008 at 3:27 pm
Hi Charles
In that picture you need to be looking in the lower quarter, and about central left to right.
Near the bottom of the image there are two large ICs. To the left is an SMC device, and to the right a TI device. Dead right of the side-on ‘M’ from SMC is a small device in a white rectangle. This is the U45 device. If you look really closely you can just make out the FCAA printing on the top.
There’s another picture about halfway down this Polish forum thread showing a 10k resistor wired across the damaged deveice, which apparently acts as a sort of fix:
http://www.elektroda.pl/rtvforum/topic876611.html
IanC
November 8th, 2008 at 9:59 am
Hi Guys;
I’m trying to fix a Dell C640 (that I bought off eBay) that turns on, then off almost immediately.
The longest it stays on is about 15 seconds or so.
When it stays on for 10-15 seconds I get the msg that the time is not set, try to enter the BIOS, then before I can save any changes the laptop shuts off.
The battery has a charge and I’ve tried two other batteries — but it won’t run for 6-10 seconds on battery. Once it shuts down, I’ve got to let it set for several minutes to get it to start again.
When I plug the AC adaptor in (I’ve tried two that I know are good) the AC light on the laptop sometimes comes on and then goes off — but most of the time the AC light doesn’t even come on.
I read on Google about the C540 having this problem when the CMOS battery dies — not sure if this is true for a C640 — but I replaced the CMOS battery with one from another C640 that does work — no joy.
I also read about the power jack. I took the laptop apart and re-soldered the pins on the MB — no joy.
I am thinking I need to replace u45 and am wondering if someone can point it out in this photo (my eyesight ain’t so good these days):
http://i7.photobucket.com/albums/y285/Jungesblut/Stuff/U45.jpg
Oh… and if anyone has any other advice, I would appreciate it.
If I get this thing fixed, I definitely let everyone know what the problem was and what it took to fix it.
TIA.
November 7th, 2008 at 11:49 am
Here are my notes for complete disassembly of a C640 to bare motherboard. They’re written in a pretty terse style, but will hopefully be an aid to disassembly, and more importantly reassembly.
The first section gets as far as Dell’s own instructions for replacing the mobo that can be found in the online C640 service manual. Uisng that guide with its pictures may be helpful.
Case legend
———–
[K] means ‘Screws labelled K on plastic/stickers’, etc.
Screw legend
————
(K) : M2.5 x 15
(P) : M2 x 3
(D) : M2.5 x 5
(Q) : M3 x 5
(R) : M2 x 16
(S) : M3 x 3
Remove motherboard assembly
—————————
Keyboard screws [K]: 5x(K) on base (4 if memory cover not in place)
Keyboard, unplug ribbon cable
Filler/button strip
Screen ribbon cable screws: 4x(P), screen cable plug
Display assembly screws [D]: 5x(D) on rear
Palm rest screws [P]: base 3x(K), drive bay 2x(P), top rear edge 2x(P), riser near heatsink (P)
Palm-rest ribbon cable & assemmbly
Base screws [B]: internal (D), fan surround 3x(D), base 6x(D)
Speaker assemblies: push-fit
Mic/headphone sockt fitting: ease case around to avoid damage
Motherboard assembly: friction / moulding fit
Remove PCB from assembly
————————
CMOS battery cable
Button/GPU shield screws: 5x(P), NB: two holes empty for securing display cable
GPU ribbon cable: slide retention tabs
GPU assembly: push-fit to motherboard
Front guard screws: 3x(P)
Speaker/mic r/h assembly: 2 x m/b plug
Speaker l/h assembly: 1 x m/b plug
Dive cage: 3x(Q), PCMCIA cage (R)
Rear trim: 3x(P), PCMCIA cage 2x(R)
PCMCIA cage: (R), detach cage
CPU heatsink
Fan cable: m/b plug at 2 locations
Hex stand-off: silver @ JTV1, bronze @ C56
Rear port connector retention hex bosses
Lower metal assembly
Modem cable: 2 connectors @ base
Test PCB
——–
Attach video/button assy
Attach LED assy
Use stand-offs to attach heatsink
Put battery/power in place
Turn-on
Drive caddy
———–
Caddy retention: (Q)
Disk attachment: 2x(S)
NB: If (S) is unavailable then (Q) is compatiable with many drives
November 5th, 2008 at 3:09 pm
Hi,
Thank you all for sharing your knowledge here.
My C640 also had that shutdown syndrome.
I`ve replaced the U45 (S60) with a U67 (FCAA) from a Latitude C600 as shown here before.
Now the notbook is running again since hours without any shutdowns so the problem seems to be fixed!
Regards Cab
October 30th, 2008 at 11:28 am
To Ian C
Many thanks for your info.
I eventually chickened out and put it all together again.
I had reached the point of having only one large tin plate to remove (this has riveted to it a small section that surrounds the power plug) but there appeared to be many more screws to remove that had their heads under other small circuit boards, so I felt that I was adventuring too far into the unknown, and with lots of little heaps of screws and sections carefully set out on the furniture I gave up.
However the frequent flashing of the screen means that I will have to have another go at it, this time as you suggest with a nice little compartmented box.
Thanks again Mike K
October 19th, 2008 at 3:23 pm
To Mike Bush:
I live in Australia and I ordered the part from http://www.newark.com/ off the web and they delivered very cheeply and quickly. I would recommend purchasing from them. Now I have to find someone to solder it on for me with the resistor. Again if someone has a pic of how they fitted the resistor it would fantastic and greatly appreciated.
Regards
October 19th, 2008 at 2:56 pm
To Mike K…
Nothing is actually spot welded to the board: a couple of the tin bits are tacked to each other but everything comes away in the end.
I’ve stripped these boards a couple of times, and everything has gone back together neatly. The fiddliest bit is a few miniture cable connectors for things like the loudspeakers. Remember to reattach these before putting al the screws in…
I don’t have a formal stripdown guide, but the tools I use are the largest cross-head from a set of jewellers’ screwdrivers, plus a ‘fishing tackle’ type box that has a number of shallow indentations in the top. Work methodically and put each set of screws in a separate tray and it helps you keep track of putting it back together (and if you seme to have a screw spare at some point).
IIRC, the main order of work is:
1) Remove cover to top rear over switches and graphics board.
2) Remove HDD caddy housing and PCMCIA slots.
3) Loosen vertical trim around front/battery connectors.
4) Remove remaining screws and detach wiring connectors.
HTH
October 19th, 2008 at 2:40 pm
There seem to be a couple of different issues in this thread, so I’m having trouble making sure I’m following it…
I have a C640 that won’t start up: no apparent response to pushing the power button. Should I be checking the U45 device? Can I check it in place on a powered down board with a standard multi-meter, and if so what am I looking for in a good and bad device?
I’m happy stripping the board down (I’ve previously soldered a new USB port onto another C640). Assuming I determine the device is bad is this an equivalent part (from RS in the UK):
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6248236
or perhaps this:
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6248365
Many thanks for any help on this.
October 19th, 2008 at 11:27 am
Emiliano..
Many thanks for your interest and suggestion, I have checked the cables on the ac adapter and they appear good. I still have’nt taken off the tinware from the motherboard to investigate further.
Regards Mike
October 18th, 2008 at 4:34 am
Hi all you have done a good job finding the route cause of this problem but I am finding it very hard finding a component supplyer in the uk who stocks them can anyone help me.
It would be cool getting the c640 up and running again.
October 17th, 2008 at 3:36 am
Dear John,
Can you please tell me which soldering device you used for dismentaling the u45 IC?
Thanks in advance.
October 14th, 2008 at 5:23 pm
Mike, this can be the power ac wire is cut somewhere. I had a similar problem with my ac adapters and it was cut somewhere. I was able to repair this. Test the wire and look very well because it is hard to see. If you can’t understand what I’m saying is because I don’t speak english very well. Regards.