Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old January 15th 16, 09:17 AM posted to sci.electronics.repair
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Default Key contact restoration




I'm having a hard time reconciling your text with your picture.
Looks more like 1cm cubes?
And the contact is the circular spot on the bottom of the key?
Rather large???
What part got removed by the customer?






Sorry, that's a typo, that should be 10mm x 10mm x 10mm cubes, as the ruler
in the photo shows.
That same photo with the ruler shows the round pad to be about 5mm diameter,
much larger than the key contact strips and button pads I find on
contemporary equipment.
This is old school manufacturing.




Gareth.


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Old January 15th 16, 09:22 AM posted to sci.electronics.repair
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Default Key contact restoration

I'm having a hard time reconciling your text with your picture.
Looks more like 1cm cubes?
And the contact is the circular spot on the bottom of the key?
Rather large???
What part got removed by the customer?







The customer has ripped out all the contact buttons on the right side of the
keyboard, the left side set is still in place and working.
The photo shows the right hand side of the PCB with 2 buttons from the left
side put in the photo to show the size of things.



Gareth.

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Old January 15th 16, 10:46 AM posted to sci.electronics.repair
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Default Key contact restoration

On 1/15/2016 1:22 AM, Gareth Magennis wrote:
I'm having a hard time reconciling your text with your picture.
Looks more like 1cm cubes?
And the contact is the circular spot on the bottom of the key?
Rather large???
What part got removed by the customer?







The customer has ripped out all the contact buttons on the right side of
the keyboard, the left side set is still in place and working.
The photo shows the right hand side of the PCB with 2 buttons from the
left side put in the photo to show the size of things.



Gareth.

OK,
I can't imagine you can manufacture new keys at a repair price the
customer could tolerate.

There's a guy who shows up at local ham radio swapmeets and sells
radio attachment gizmos.
He has a 3D printer and claims to be willing and able to make custom gizmos.
I never asked the price.
All his samples were rigid.
Unknown whether he could make the bottom section springy enough
to effect a pushbutton spring.
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Old January 15th 16, 01:53 PM posted to sci.electronics.repair
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Default Key contact restoration

I have a stupid question.....are keyboards connected to a connector ? is there an assembly area into the registering circuit ?

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Old January 15th 16, 04:31 PM posted to sci.electronics.repair
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Default Key contact restoration

On 2016-01-15, Gareth Magennis wrote:
--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

---



Thanks, might give that a go.


Look, you quoted Jeff without using the correct characters,
*including his signature*, and put your reply after the signature!

Without the characters, it looks like your posting is a plagiarism
of Jeff.

When I went to reply to you, your entire reply disappeared, because
your reply looks like an extension of Jeff's signature, and a proper news
client removes everything after the "-- " signature mark when you reply. I had
to copy and paste the above from the terminal.

Please use Usenet correctly or FOAD.


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Old January 15th 16, 04:31 PM posted to sci.electronics.repair
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Default Key contact restoration

On Fri, 15 Jan 2016 09:11:00 -0000, "Gareth Magennis"
wrote:

Is there a tried and trusted way of adding a conductive contact pad?


Search for a rubber keypad repair kit:
http://www.amazon.com/MG-Chemicals-8339-Rubber-Keypad/dp/B0081SGM8M
http://www.amazon.com/Keypad-Restore-Conductivity-Carbon-Copper/dp/B0026PRMVM
http://www.amazon.com/Caig-BCG327782-Caikote-44-Kit/dp/B00E1QYYC4
http://www.mcmelectronics.com/product/CAIG-LABORATORIES-K-CK44-G-/200-315
http://www.ebay.com/bhp/keypad-repair-kit
http://www.ebay.com/bhp/keypad-fix
There are videos on YouTube on how to apply the stuff. My favorite
mistake was to apply too much graphite paint. It's not very flexible
and will tend to crumble around the edges. Loose pieces of conductive
graphite inside the switch is not a good thing.


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

---
This email has been checked for viruses by Avast antivirus software.
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Old January 15th 16, 07:15 PM posted to sci.electronics.repair
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Default Key contact restoration

On Thu, 14 Jan 2016 17:11:25 -0800, Jeff Liebermann
wrote:

On Thu, 14 Jan 2016 23:01:20 -0000, "Gareth Magennis"
wrote:

Anyone any such experience here?
I know it's a long shot.


Google for "mold your own rubber parts" or "cast your own rubber
parts". Lots of lousy videos on YouTube on how to mold rubber parts.
I use Plaster of Paris for the mold, Devcon Flexane 94 Liquid 15250
two part urethane rubber
http://www.devcon.com/products/products.cfm?family=Flexane%C2%AE%2094%20Liquid
http://www.amazon.com/Devcon-15250-Black-Flexane-Liquid/dp/B00065TLJK
and Vaseline or silicon grease for mold release. Careful when storing
the stuff as the stuff in the bottle attacks the bottle and causes it
to leak. It cures in 10-15 mins, so be prepared to work fast.
Although it's made for making flex molds, it's also the right stuff
for making fairly hard rubber buttons, gaskets, shock mounts, seals,
etc.


Oops. The Devcon Flexane 94 is probably too hard and stiff for your
rubber button that has to bend and act as a spring:
http://oi65.tinypic.com/14xdmo3.jpg
Something more like RTV (silicone rubber) will be more flexible. I
have a Shore A Durometer (rubber hardness meter) and can measure a few
random rubber buttons and see what's appropriate. Well, the assorted
TV remote controls run 53 to 60. Various other rubber buttons vary
from 50 to 65. All my music keyboards have hard plastic buttons, so
that's not going to work.

I found a part I had made using Flexane 94, which shows 85, so that's
much to hard to flex. I don't have something handy that will work,
but I'll do some catalog searching this weekend. Offhand, I would
suspect that bathroom caulk, rain gutter seal, or other commonly
available silicone rubber compound might work but might also be too
soft (typically 25 to 30 durometers). Structural silicone might be
harder. Digging:
http://www.siliconeforbuilding.com/pdf/structuralglazing/Data_Sheet_SSG4000_UltraGlaze.pdf
Argh... only 39.

These might help:
"Using Silicone Caulk as a Mold Material"
http://forums.gardenweb.com/discussions/1472166/using-silicone-caulk-as-a-mold-material

Durometer Hardness Scales:
http://www.paramountind.com/pdfs/paramount_durometer_scale_guide.pdf

MasterBond Adhesive hardness:
http://www.masterbond.com/properties/hardness


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

---
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Old January 15th 16, 07:30 PM posted to sci.electronics.repair
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Default Key contact restoration

In article ,
Gareth Magennis wrote:

Is there a tried and trusted way of adding a conductive contact pad?


For what it's worth: I've had pretty good luck restoring conductive
pads using a product called Neolube #2. It's a water/alcohol
suspension of extremely fine graphite, with a small amount of a
thermoplastic resin (possibly cellulose acetate?) as a binder. It can
be applied with a fine brush or Q-tip.

I recently purchased a bunch of surplus Kenwood UHF mobile radios.
About half of them had intermittent or non-working keys on the molded
keypads. The pad sheet had originally been made with some sort of
sprayed-on or molded-on conductive coating, and I could see where it
had been worn off the keys in question (the rubber was shiny and I
could actually see the shapes of the corresponding PC-board traces).

Cleaned with alcohol, painted on a couple of thin coats of Neolube,
and they work fine.

I can't swear as to how long it will hold, but Neolube seems to have a
respectable "grip" on the surfaces I've painted it onto. Its info
sheet is interesting... they talk about how its carbon is so pure than
neutron activation of contaminants isn't an issue, and so it's rated
for use in nuclear reactors.



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Old January 15th 16, 08:38 PM posted to sci.electronics.repair
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Default Key contact restoration



"Kaz Kylheku" wrote in message ...

On 2016-01-15, Gareth Magennis wrote:
--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

---



Thanks, might give that a go.


Look, you quoted Jeff without using the correct characters,
*including his signature*, and put your reply after the signature!

Without the characters, it looks like your posting is a plagiarism
of Jeff.

When I went to reply to you, your entire reply disappeared, because
your reply looks like an extension of Jeff's signature, and a proper news
client removes everything after the "-- " signature mark when you reply. I
had
to copy and paste the above from the terminal.

Please use Usenet correctly or FOAD.






I would direct your juvenile rantings to Microsoft instead.
It is they who have made Live Mail do this, and they won't fix it.


Most of us seem able to cope with this though.









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