Re: Restoring rubber keyboard on a logic analyzer

[Alexandre Souza via cctalk]

http://tabalabs.com.br/videogames/atari/controle_5200/ - that is how I
solved this problem

2018-05-02 15:02 GMT-03:00 Paul Koning via cctalk :

>
>
> > On Apr 29, 2018, at 11:44 PM, Tony Duell via cctalk <
> cctalk@classiccmp.org> wrote:
> >
> > ...
> > It's not cheap (and IIRC you have to use the whole lot in one go), but
> > Chemtronics make a kit to repair such keypads. Possibly worth it for
> > a useful instrument though.
> >
> > In the UK you can get it here :
> >
> > https://uk.rs-online.com/web/p/conductive-adhesives/3888673/
> >
> > and I guess it's also available across the Pond.
> >
> > -tony
>
> It is, and for less money.  The various electronic and industrial supply
> outlets carry it, for example Newark, Digikey, and MSC Direct.  Digikey
> sells it for $23, that's significantly better than 23 pounds...
>
> The Aquadag approach looks interesting, but that may not be as reliable.
> That seems to be a conductive coating intended for rigid objects like CRTs,
> as opposed to a substance intended to repair rubber keypads.
>
> So if my graphite cure doesn't last, it sounds like the Chemtronics
> products is the next answer.
>
> Thanks!
>
> paul
>
>

Re: Restoring rubber keyboard on a logic analyzer

[Paul Koning via cctalk]

> On Apr 29, 2018, at 11:44 PM, Tony Duell via cctalk  
> wrote:
> 
> ...
> It's not cheap (and IIRC you have to use the whole lot in one go), but
> Chemtronics make a kit to repair such keypads. Possibly worth it for
> a useful instrument though.
> 
> In the UK you can get it here :
> 
> https://uk.rs-online.com/web/p/conductive-adhesives/3888673/
> 
> and I guess it's also available across the Pond.
> 
> -tony

It is, and for less money.  The various electronic and industrial supply 
outlets carry it, for example Newark, Digikey, and MSC Direct.  Digikey sells 
it for $23, that's significantly better than 23 pounds...

The Aquadag approach looks interesting, but that may not be as reliable.  That 
seems to be a conductive coating intended for rigid objects like CRTs, as 
opposed to a substance intended to repair rubber keypads.

So if my graphite cure doesn't last, it sounds like the Chemtronics products is 
the next answer.

Thanks!

paul

Re: Restoring rubber keyboard on a logic analyzer

[Chuck Guzis via cctalk]

Answered my own question.  The repair stuff is called "Aquadag E":

https://semicro.org/products/carbon-paint-conductive

https://www.ebay.com/itm/AQUADAG-CARBON-PAINT-ARCADE-MONITOR-TV-CRT-CATHODE-REPAIR-SPARES-30-ML-BRUSH-/261808496366

Should work a treat in this application.

--Chuck

Re: Restoring rubber keyboard on a logic analyzer

[Chuck Guzis via cctalk]

On 04/29/2018 08:44 PM, Tony Duell via cctalk wrote:

> It's not cheap (and IIRC you have to use the whole lot in one go), but
> Chemtronics make a kit to repair such keypads. Possibly worth it for
> a useful instrument though.
> 
> In the UK you can get it here :
> 
> https://uk.rs-online.com/web/p/conductive-adhesives/3888673/
> 
> and I guess it's also available across the Pond.

Does anyone still make aquadag?

--Chuck

Re: Restoring rubber keyboard on a logic analyzer

[Fred Cisin via cctalk]

On Mon, 30 Apr 2018, Tony Duell via cctalk wrote:

In the UK you can get it here :
https://uk.rs-online.com/web/p/conductive-adhesives/3888673/
and I guess it's also available across the Pond.


Silly thought:
Half a century ago, there used to be a conductive glue that was peddled 
to the general [not even owning a soldering iron] public as heat-less 
solder.


If that's still available in any form, would that work?


There is some stuff that claims to be a conductive paint:
https://www.amazon.com/Bare-Conductive-BarePaint-Paint/dp/B076BSBMK6

Re: Restoring rubber keyboard on a logic analyzer

[Tony Duell via cctalk]

On Sun, Apr 29, 2018 at 11:29 PM, Maciej W. Rozycki via cctalk
 wrote:
> On Sun, 29 Apr 2018, Paul Koning via cctalk wrote:
>
>> So that's the answer: graphite powder.  I now have a working analyzer
>> again.  It will be interesting to see if the graphite wears off
>> eventually, I suppose it might but that's ok, I can just do it again.
>
>  Many years ago I used graphite obtained from a soft pencil to revive
> rubber keyboard pads and from my observation it wore rather quickly, in
> particular moving to the surface contact was made against.  I wonder if
> there is a non-industrial way to make graphite stay in place on rubber.

It's not cheap (and IIRC you have to use the whole lot in one go), but
Chemtronics make a kit to repair such keypads. Possibly worth it for
a useful instrument though.

In the UK you can get it here :

https://uk.rs-online.com/web/p/conductive-adhesives/3888673/

and I guess it's also available across the Pond.

-tony



>
>   Maciej

Re: Restoring rubber keyboard on a logic analyzer

[Maciej W. Rozycki via cctalk]

On Sun, 29 Apr 2018, Paul Koning via cctalk wrote:

> So that's the answer: graphite powder.  I now have a working analyzer 
> again.  It will be interesting to see if the graphite wears off 
> eventually, I suppose it might but that's ok, I can just do it again.

 Many years ago I used graphite obtained from a soft pencil to revive 
rubber keyboard pads and from my observation it wore rather quickly, in 
particular moving to the surface contact was made against.  I wonder if 
there is a non-industrial way to make graphite stay in place on rubber.

  Maciej

Re: Restoring rubber keyboard on a logic analyzer

[Paul Koning via cctalk]

> On Apr 26, 2018, at 12:32 PM, Electronics Plus via cctalk 
>  wrote:
> 
> Easier solution is to apply some conductive light lube. Radio Shack used to
> carry it, and I repaired a LOT of remote controls with it!
> 
> Cindy

I made a successful repair.  Here are the steps I used:

As I mentioned, I tried cleaning with isopropyl alcohol, without much success.  

I realized that I could test the rubber contact points with a multimeter, 
probing two spots on the surface.  The offending keys had much higher 
resistance or simply tested open.  That made it easier to try other options 
without having to assemble/disassemble each time.

I found a spray can of "contact cleaner/lubricant" and tried that.  OOPS.  Made 
it much worse.  Looked at the ingredients: one is "mineral oil".  Ok, so that's 
fine for metal wiping contacts I suppose, but not for this.  Washed the keypad 
thoroughly with dishwashing soap and water, then wiped several times with 
alcohol, that got me back to where I was.

Then I realized I still have a tube of powdered graphite (the stuff sometimes 
used for lubricating locks, though it turns out that's not a good idea.  
Squirted some onto a Q-tip and rubbed the bad contact pads with that.  They 
look shiny as a result rather than dull black.  But it works!

So that's the answer: graphite powder.  I now have a working analyzer again.  
It will be interesting to see if the graphite wears off eventually, I suppose 
it might but that's ok, I can just do it again.

Thanks everyone for the suggestions.

paul

Re: Restoring rubber keyboard on a logic analyzer

[dwight via cctalk]

Just out of curiosity, you might try a little extra fine sand paper on the 
button. You have little to loose as it doesn't work anyway.

Dwight




From: cctech <cctech-boun...@classiccmp.org> on behalf of shad via cctech 
<cct...@classiccmp.org>
Sent: Thursday, April 26, 2018 12:09:49 PM
To: cct...@classiccmp.org
Subject: Re: Restoring rubber keyboard on a logic analyzer

Hello,
this kind of keyboards was made using small pieces of conductive rubber to
close the circuit designed on the PCB.
The rubber was an uniform compound, so even with severe usage, i.e. high
consumption, the conductivity remained constant.
However, in more recent / cheaper products, the rubber is the same for the
whole keyboard, i.e. simple insulating silicone rubber.
The conductive surface is only painted over the silicone.
No doubt it comes away faster...
In this case, cleaning with alcohol just removes the remaining paint,
referring the keyboard useless.

The solution is simple: cover the key contacts with something conductive.
I know that conductive paint is sold somewhere, but it's pricey and don't
think it would last much...
The cheapo solution is to cut small pieces of aluminum foil, and glue it to
the rubber.
Given that the keyboard is almost always made by silicone, I always use
silicone glue to assure the sickness.
Be careful to put a very thin layer of it only over the center of the foil,
then put it in place and press a bit around with the fingertip to let it
take the shape of the contract.
Too much silicone would come out when pressed and would cover the graphite
on the PCB.
This method worked well with several TV remote controls.
I could suggest you to try with one key,
then let the silicone to dry before remounting the keyboard, then check the
result and eventually repeat on other keys.

Andrea

Re: Restoring rubber keyboard on a logic analyzer

[shadoooo via cctalk]

Hello,
this kind of keyboards was made using small pieces of conductive rubber to
close the circuit designed on the PCB.
The rubber was an uniform compound, so even with severe usage, i.e. high
consumption, the conductivity remained constant.
However, in more recent / cheaper products, the rubber is the same for the
whole keyboard, i.e. simple insulating silicone rubber.
The conductive surface is only painted over the silicone.
No doubt it comes away faster...
In this case, cleaning with alcohol just removes the remaining paint,
referring the keyboard useless.

The solution is simple: cover the key contacts with something conductive.
I know that conductive paint is sold somewhere, but it's pricey and don't
think it would last much...
The cheapo solution is to cut small pieces of aluminum foil, and glue it to
the rubber.
Given that the keyboard is almost always made by silicone, I always use
silicone glue to assure the sickness.
Be careful to put a very thin layer of it only over the center of the foil,
then put it in place and press a bit around with the fingertip to let it
take the shape of the contract.
Too much silicone would come out when pressed and would cover the graphite
on the PCB.
This method worked well with several TV remote controls.
I could suggest you to try with one key,
then let the silicone to dry before remounting the keyboard, then check the
result and eventually repeat on other keys.

Andrea

RE: Restoring rubber keyboard on a logic analyzer

[Electronics Plus via cctalk]

Easier solution is to apply some conductive light lube. Radio Shack used to
carry it, and I repaired a LOT of remote controls with it!

Cindy

-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Peter
Coghlan via cctalk
Sent: Wednesday, April 25, 2018 4:17 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Restoring rubber keyboard on a logic analyzer


>
> I have a Philips logic analyzer (PM3585) which is about 20 years old at
this point.  It seems to be basically functional except for the keyboard,
which unfortunately is a critical part.
>
> This is one of those molded rubber type, with a circuit board behind the
rubber that has contact areas made of carbon film (at least they are black
in color) and on the back of each key a small cylindrical bump also coated
with carbon. Some of the buttons work but most don't seem to even if I press
hard.
>
> I've disassembled the keyboard, which was easy enough.  Inspection shows
no damage and no signs of corrosion or contamination.  I wiped everything
with isopropyl alcohol anyway.  The result is no change in behavior.
>
> Any suggestions for what to do next?
>

I had a similar problem with an old VCR remote control.  The problem seemed
to be that the bumps on the back of the keys lost their conductivity (and
cleaning them made them worse).

My solution was to glue pieces of aluminium foil to the back of the keys.
It was tedious but it seemed to sort it out.

Regards,
Peter Coghlan.

paul



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Restoring rubber keyboard on a logic analyzer

[Paul Koning via cctalk]

Gentlepeople,

I have a Philips logic analyzer (PM3585) which is about 20 years old at this 
point.  It seems to be basically functional except for the keyboard, which 
unfortunately is a critical part.

This is one of those molded rubber type, with a circuit board behind the rubber 
that has contact areas made of carbon film (at least they are black in color) 
and on the back of each key a small cylindrical bump also coated with carbon. 
Some of the buttons work but most don't seem to even if I press hard.

I've disassembled the keyboard, which was easy enough.  Inspection shows no 
damage and no signs of corrosion or contamination.  I wiped everything with 
isopropyl alcohol anyway.  The result is no change in behavior.

Any suggestions for what to do next?

paul