StanF,

I can't imagine why I would buy another keyboard to fix a problem that should have been fixed by Dell at no charge. When Dell heard of this problem they should have had all the affected PCs recalled and repaired at no cost to the owners.

As for non-legal actions, don't think for a minute that when asked what I recommend, and I get asked a lot, that Dell is no longer in the mix. This is a shame because before this I regularly sang their praises.

As far as I'm concerned this is a dead issue.

You consider this a dead issue because you do not own a Dell laptop(s) with this unresolved problem. The rest of us do.

I've got an INSPIRON 4100 where sections of the keyboard failed. Keyboard replacement was not successful, nor was cleaning the connectors with either eraser or q-tips--in fact, when I did fix this problem I realized that cleaning the pins PROBABLY MADE IT WORSE!

The solution that worked for me was to take a needle and gently and patiently pry the connector pins on the mainboard just barely away from the plastic housing walls. 

Hi there.

Reviewing the various posts, I've also come to the conclusion that the root cause of the fault is probably a short circuit due to part of the keyboard contacting with a metallic component on the motherboard: the CPU cover has been sensibly suggested. Despite the fact that it doesn't seem robust from a design perspective to not have any casing or structural barrier between the motherboard circuitry/components and the metal keyboard, I would say that the following evidence supports this conclusion:

Loosening the K screws worked for some people since this presumably increases the available clearance and/or avoids warping the keyboard.

I found that my 8, i, j and k keys ceased to function some minutes after the computer had been switched on. I suspect that this was due to linear expansion of the offending component on the motherboard eventually causing contact after it has heated up sufficiently. Clearly, overtightening of the screws would reduce the available clearance and exacerbate this. It is surely no coincidence that the affected keys are clustered together in one part of the keyboard (near the left hand edge of the CPU cover). Thinking it was a some kind of software related issue, I used to switch the machine off (for varying periods of time) and then re-start. Sometimes the problem cleared and sometimes it didn't. With hindsight, I suppose that the problem would have cleared only if the computer had been switched off for long enough to allow the expanded metal component to cool, contract and break the short-circuit.

Although an appealing solution, I think that cleaning the contacts is probably a 'red herring' because the act of removing the keyboard and refitting it could itself result in the K screws not being tightened as much as they were before due to increased caution on the repairer's behalf. I note that one person recommends cleaning and another warns against it: conflicting advice which tends to cancel this out as a reasonable course of action.

I think that corrosion or oxidation of the contacts either on the male (keyboard) or female (motherboard) multi-pin connector is unlikely for several reasons: (1) the fit is quite tight thus minimising overall exposure to atmosphere, (2) the computers are being used in benign domestic or office environments, (3) The connectors do not suffer repetitive connection and disconnection cycles so there should not be any wear and tear (4) It is unlikely that the metal used for the connectors will oxidise or corrode to any significant extent and (5) If oxidation does occur, it should be progressive and affect all pins uniformly which would cause gradual malfunction of all keys. Conversely, if oxidation were in some way random, this could not result in malfunction of the same keys on every laptop.

If short-circuiting is indeed the correct root cause, then adding an insulating barrier between the motherboard and the keyboard should cure the fault. In any case, it is probably no bad thing to have a semi-rigid barrier between the keyboard and motherboard. A suitable material needs to be (1) not significantly more than 1 mm in thickness to avoid excessive loss of available thread on the screws, (2) be an electrical insulator (obviously) and (3) withstand the temperatures generated within the device. I am trying to get hold of an A4-sized offcut of PTFE sheet from a local engineering plastics supplier to cut down to shape, but I wonder whether any of the following might also suffice:

- Electrical insulating tape (noting one person has successfully implemented this)
- Sheet of thin formica of the type used to cover kitchen work surfaces
- Heavy duty overhead projector transparency or laminator film
- Heavy duty vinyl as used for industrial safety signs
- Teflon matting as used on splash guard products for domestic cooking appliances

-Some people are reporting a piece of paper has the desired effect.

I found the 'Properties of Engineering Plastic Materials' section of the RS catalogue helpful because it lists data such as strength, surface and volume electrical resistance, and long term/short term maximum service temperature.

Incidentally, I've had a refurbished Latitude CPx since April 2003 and am otherwise quite happy with it. It was a replacement unit since the first one had several other faults (two dead pixels and successive faulty optical drives). I had issues with the supplier too, but that's not for this forum. The keyboard connector on the replacement unit was semi-permanently cemented in place with a translucent plastic compound probably specifically intended for use on printed circuit boards. I can only surmise that this was a lash-up to try to cure the malfunctioning key problem. When the keyboard inevitably failed, I had to remove the compound with a screwdriver to disconnect it. Unforunately, the connector sheared from its ribbon cable and I decided to simply buy a wireless keyboard and optical mouse to circumvent the problem. I've recently resolved to get a replacement U.S. keyboard and attempt a permanent fix along the lines I've suggested since it's not always convenient to use separate devices.

I hope my input is helpful and has added value to this discussion thread... I'll repost in a few months to report back on whether this mod has been successful.

Regards,

Dr Doug Short
Cumbria, United Kingdom

Dear Dougmshort

Thank you for taking the time to share your information. I will try your solution of inserting a piece of heat resistant material between the motherboard and keyboard. I wouldn't bother except that it looks like I will be keeping the machine longer than I expected. Luckily I only use it as a backup.

A lot of people have mentioned that loosening the screws helped them. I just thought I'd mention that with my Inspiron 3800, I initially observed occasional problems with the i key which seemed to go away after lifting up/shaking the computer (I thought there was some dirt under the key itself). Then I realized that the whole line of 8 i k , keys was involved.  This went away sometimes after flexing the case and finally seemed to work consistently if I placed the computer on top of some junk mail in order to keep the case slightly flexed.  It was only after discovering this forum and learning that this is a common problem before I thought to look at the screws.  One of the keyboard screws (closest one to the i key) was very loose.  I tightened that one up as well as the rest of them and the problem seems to have been resolved for now (though it's only been a couple of days).

Anyway I just thought I'd mention that tightening, rather than loosening, the screws seems to have helped in my case.  Perhaps there is more than one mechanism causing this issue though I find it very odd that Dell engineering hasn't figured out the root problem and posted a resolution after all these years.

Anyway I'm very glad that it looks like I will get a little longer use of this computer than I had feared.  Thanks.

Sounds like a great fix.

Here is what I have done. I removed the keyboard and laid it on a sheet of wax paper. That's right, regular household, cooking waxpaper, the kind your grandmother used. I then traced the keyboard and the rest is obvious. It is going 3 months now without an incident of malfunctioning keys.

---

@clafave wrote:

I have a Latitude CPx and had tried all of the remedies, especially related to the keyboard shorting out. Nothing worked for more than a week if at all. Since I use WD-40 (spray-on all-purpose lubricant/ penetrating oil) to coat my tools against oxidation and some electronics plug-ins, e.g. headphone jacks, I figured that a film of it wouldn't hurt. I applied it a few months ago and all keys and the touchpad have worked perfectly ever since.

Procedure:

I removed the keyboard and sprayed the WD-40 on my finger. Then I let the drop get into both plugs: the one with like 32 or 64 pins or whatever, and also dabbed the printed-film connector (it has maybe 4 electrode traces on it). I then blew on them to remove as much excess as possible, just leaving a protective coat.

My theory is that the engineers' blunder was in using metals in the connectors that were excessively oxidation-prone or that electrolized during use, leaving an insulating film, possibly similar to the invisible film that can build up on car-battery terminals and clamps, eventually blocking current enough that the car won't start.

---