Re: Info about the key contacts WAS: Toshiba laptop keyboard request

from LR <dulcaduo-county.com> wrote:

BJ and ALL,

I HOPE this helps.&nbsp; Here's info that hopefully answers your question (below).
Russ may have more 'up to date' info. ; Mine may be <groanS> 'dated'

The "metal lines" are the foil, often silver/an alloy 'traces' the conductors
that used to be wires.&nbsp; The 'traces' may or may not transition to 'contacts'
(2 uninsulated [bare] metal areas).&nbsp; The underside of the "rubber nib" is
the upper conductor / contact.&nbsp; The underside is coated with a carbon
(conductive paint) that when pressed down effectively 'shorts' or contacts
the bare metal contact areas 'closing the switch'.&nbsp; Or, when you press the
key (including the space bar) the rubber membrane with conductive coating
allows a small current to flow across / between the two contact pads.

I dare NOT speak about current composition of contact surfaces, but in
the past and probably currently, unless the rubber membrane is actually
bonded / sealed to the circuit board, air, moisture, dirt, airborne grease /
body oils, etc. can coat (contaminate) the metallic (conductive) surface
effectively insulating it.  Sometimes the carbon coating on the underside
of the membrane wears / flakes away reducing conductivity to the point
the carbon does not conduct (make contact with the metal surface).&nbsp;
Either way, there is no current flow thus NO space (or other letter /
character).

If you are gentle & cautious you can carefully using a CLEAN pencil
eraser or even an ink eraser and erase any contamination on the metal
contacts and if the carbon coating is contaminated you may be able to
clean it.  They make conductive (carbon base) coating/paint, but Russ
would be more likely to know if it's worth the money / WORKS?

Hope this HELPS!

Mrs. Robin A-W, CET

B.J. wrote:

web58911.mail.re1.yahoo.com" type="cite">

Thanks for the reply. Yes it is only the space bar.  It does appear to work mechanically, but the cursor doesn't move when it is depressed. I was able to lift the spacebar up without breaking the plastic sissors, and I even took off the rubber nib cover and reseated it. Is the contact you are referring to under the rubber nib? If so, what do you recommend I use to clean the contact?&nbsp; There are metal lines under the spacebar cover, but I am assuming the contact you are referring to is under the rubber nib?

BTW, I did try Ebay....it was cheaper elsewhere actually.

Again, thanks for the help.

 

B.J.

 

Ardell Faul icehouse.net"><ardellicehouse.net> wrote:

Is it only the space bar?  The keys are multiplexed in sort of an X-Y grid, otherwise yo would need a seperate line for each key.  So if one of the traces gets disconnected, usually about 5 or 6 different keys will no longer work. ; If it is only the space bar and nothing else, you may just have a bad contact where the little rubber contactor touches the 2 lines together when you press on it.  If you are handy, you might be able to carefully lift the space bar up without breaking the plastic scissors underneath and see if you can clean it or such. ; Unfortunately, the space bar is usually the most difficult of all to take on an d off, since it spans 2 or 3 scissor pivot points.&nbsp; Check Ebay for a replacement keyboard, if you haven't already done so.

Ardell Faul  Computer Monitor Service Inc.  Laptop Computer & Monitor Repair  10816 E. Mission Ave.,  Spokane Valley, Wa.  99206  icehouse.net">ardellicehouse.net  509-891-5188

B.J. wrote:

web58911.mail.re1.yahoo.com" type="cite">

5 months into owning a new Toshiba Satellite (90 day warrenty!) the keyboard space bar suddenly quit working. I have the keyboard out, and have attempted repair to no avail.&nbsp; Anyone on the list ever succeeded in a laptop keyboard repair? The cheapest replacement I can find is $50 with shipping.

---

No virus detected / found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.5.441 / Virus Database: 268.17.33/678 - Release Date: 2/9/07 4:06 PM

2;

B.J.,

You are, of course welcome.&nbsp; We've used alcohol with a cotton tip swab, but
a foam tip/covered swab is probably better, since it is less likely to leave fibers.

We've also used video head cleaner (which is supposed to be carbontetachloride
free), either it's freon or a similar chemical.

I'm not familiar with Rail-Zip, though I suspect it should be fine. ; We've used,
gently, a clean rubber eraser to 'clean the surface' of the carbon compound.

Many microwaves use / used the mylar films (one conductive, one with the
metal/foil contact points with an insulating separator containing a hole beneath
each 'button' / keypad) similar to the ones  Russ mentioned

Be well and be SAFE!

Mrs. Robin A-W, CET
----------------------------
B.J. wrote:

web58903.mail.re1.yahoo.com" type="cite">

Mrs. Robin A-W and all,

 

Great information, and very helpful, thanks!&nbsp; After reading your anwer my hunch is that the carbon coating under the rubber membrane might ;be compromised but I will try to gently and carefully clean the contact point with a clean pencil eraser.&nbsp;How would I clean the carbon coating - assuming it isn't flaked off?  Incidentally, I have some solution that is meant for cleaning electrical connections called RAIL-ZIP.&nbsp; It says "no alcohol, solvents or acid", but no indication about what it does contain.&nbsp; Have you ever heard of it and would you think it safe to use as a contact cleaner?

 

Great group!&nbsp; So helpful!

 

 

from LR duo-county.com"><dulcaduo-county.com> wrote:

BJ and ALL,

I HOPE this helps.&nbsp; Here's info that hopefully answers your question (below).
Russ may have more 'up to date' info. ; Mine may be <groanS> 'dated'

The "metal lines" are the foil, often silver/an alloy 'traces' the conductors
that used to be wires.&nbsp; The 'traces' may or may not transition to 'contacts'
(2 uninsulated [bare] metal areas).&nbsp; The underside of the "rubber nib" is
the upper conductor / contact.&nbsp; The underside is coated with a carbon
(conductive paint) that when pressed down effectively 'shorts' or contacts
the bare metal contact areas 'closing the switch'.&nbsp; Or, when you press the
key (including the space bar) the rubber membrane with conductive coating
allows a small current to flow across / between the two contact pads.

I dare NOT speak about current composition of contact surfaces, but in
the past and probably currently, unless the rubber membrane is actually
bonded / sealed to the circuit board, air, moisture, dirt, airborne grease /
body oils, etc. can coat (contaminate) the metallic (conductive) surface
effectively insulating it.  Sometimes the carbon coating on the underside
of the membrane wears / flakes away reducing conductivity to the point
the carbon does not conduct (make contact with the metal surface).&nbsp;
Either way, there is no current flow thus NO space (or other letter /
character).

If you are gentle & cautious you can carefully using a CLEAN pencil
eraser or even an ink eraser and erase any contamination on the metal
contacts and if the carbon coating is contaminated you may be able to
clean it.  They make conductive (carbon base) coating/paint, but Russ
would be more likely to know if it's worth the money / WORKS?

Hope this HELPS!

Mrs. Robin A-W, CET

B.J. wrote:

web58911.mail.re1.yahoo.com" type="cite">

Thanks for the reply. Yes it is only the space bar.  It does appear to work mechanically, but the cursor doesn't move when it is depressed. I was able to lift the spacebar up without breaking the plastic sissors, and I even took off the rubber nib cover and reseated it. Is the contact you are referring to under the rubber nib? If so, what do you recommend I use to clean the contact?&nbsp; There are metal lines under the spacebar cover, but I am assuming the contact you are referring to is under the rubber nib?

BTW, I did try Ebay....it was cheaper elsewhere actually.

Again, thanks for the help.

 

B.J.

 

Ardell Faul icehouse.net"><ardellicehouse.net> wrote:

Is it only the space bar?  The keys are multiplexed in sort of an X-Y grid, otherwise yo would need a seperate line for each key.  So if one of the traces gets disconnected, usually about 5 or 6 different keys will no longer work. ; If it is only the space bar and nothing else, you may just have a bad contact where the little rubber contactor touches the 2 lines together when you press on it.  If you are handy, you might be able to carefully lift the space bar up without breaking the plastic scissors underneath and see if you can clean it or such.&nbsp; Unfortunately, the space bar is usually the most difficult of all to take on and off, since it spans 2 or 3 scissor pivot points.&nbsp; Check Ebay for a replacement keyboard, if you haven't already done so.

Ardell Faul  Computer Monitor Service Inc.  Laptop Computer & Monitor Repair  10816 E. Mission Ave.,  Spokane Valley, Wa.  99206  icehouse.net">ardellicehouse.net  509-891-5188

B.J. wrote:

web58911.mail.re1.yahoo.com" type="cite">

5 months into owning a new Toshiba Satellite (90 day warrenty!) the keyboard space bar suddenly quit working. I have the keyboard out, and have attempted repair to no avail.&nbsp; Anyone on the list ever succeeded in a laptop keyboard repair? The cheapest replacement I can find is $50 with shipping.

---