Graphite for membrane key-pads! - UK Vintage Radio Repair and Restoration Discussion Forum

brenellic2000 · 20th Feb 2013, 4:02 pm

My (long obsolete) Calcomp 2000 CAD puck is getting old - the keys are not as responsive as they were 25+ years ago. We used to revive the membrane contacts with a graphite pencil but is there special graphite 'paint' or powder available for this or is it once again 'B' pencils?

Barry

M0TGX Terry · 20th Feb 2013, 4:34 pm

Hi Barry,
Try googling "graphite powder". There seems to be quite a range available in different pack sizes for a variety of uses (eg it's used by locksmiths and as a colouring pigment in casting resin, so you may be able to get some at a local locksmith or craft shop. Otherwise, it's back to pencil lead and glasspaper!
All the best
Terry

Nickthedentist · 20th Feb 2013, 4:49 pm

Quote:

Originally Posted by M0TGX Terry

...it's used by locksmiths...

e.g. http://www.ebay.co.uk/itm/C-K-Graphi...item20cf5cf2e0

I've also had success gluing-on little discs of aluminium cooking foil, formed by placing the foil over a piece of old Christmas card and using a hole punch like one would use to make the holes in paper so that it can go in a ring binder.

N.

Radio Wrangler · 20th Feb 2013, 6:13 pm

You can buy the conductuve pieces. look up 'carbon pills' and avoid the flatulence treatments

David

Herald1360 · 21st Feb 2013, 1:15 am

I believe there's a graphite/glue spray (used for spraying conductive coatings on plastic boxes?) that's good for this. This stuff I believe:

http://www.rapidonline.com/mechanica...coating-30090/

Philips210 · 21st Feb 2013, 10:52 am

Quote:

Originally Posted by Herald1360

I believe there's a graphite/glue spray (used for spraying conductive coatings on plastic boxes?) that's good for this. This stuff I believe:

http://www.rapidonline.com/mechanica...coating-30090/

That also looks good for repairing damaged aquadag coating on CRTs. Thanks for the link.

Regards
Symon.

brenellic2000 · 21st Feb 2013, 1:47 pm

Thanks lads... I think a one litre can might be a tad OTT!

Vicboduk · 21st Feb 2013, 2:36 pm

How about this from CPC. I'm not an "e-bay" person but I suspect if you search for "keypad repair kit" you may find something cheaper.

Vic

camallison · 21st Feb 2013, 5:40 pm

I have successfully used this in the past.

Colin

brenellic2000 · 22nd Feb 2013, 3:09 pm

I have always shied away from using graphite powder on membranes in case it 'falls off and shorts' - does it stick satisfactorily to the rubber and ipso facto, my fears needless?

Barry

MrElectronicman · 23rd Feb 2013, 10:44 pm

I found a repair kit (in the USA) for one of my keypads. It was some sort of paint, much like the heated rear window repair kit used for cars. Worked for a couple of more years.

20th Feb 2013, 4:02 pm	#1
brenellic2000 Octode Join Date: Aug 2006 Location: Rye, East Sussex, UK. Posts: 1,647	Graphite for membrane key-pads! My (long obsolete) Calcomp 2000 CAD puck is getting old - the keys are not as responsive as they were 25+ years ago. We used to revive the membrane contacts with a graphite pencil but is there special graphite 'paint' or powder available for this or is it once again 'B' pencils? Barry

20th Feb 2013, 4:34 pm	#2
M0TGX Terry Hexode Join Date: Sep 2005 Location: Grantham, Lincolnshire, UK. Posts: 262	Re: Graphite for membrane key-pads! Hi Barry, Try googling "graphite powder". There seems to be quite a range available in different pack sizes for a variety of uses (eg it's used by locksmiths and as a colouring pigment in casting resin, so you may be able to get some at a local locksmith or craft shop. Otherwise, it's back to pencil lead and glasspaper! All the best Terry __________________ Terry the Morganist

20th Feb 2013, 6:13 pm	#4
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,876	Re: Graphite for membrane key-pads! You can buy the conductuve pieces. look up 'carbon pills' and avoid the flatulence treatments David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

21st Feb 2013, 1:15 am	#5
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Graphite for membrane key-pads! I believe there's a graphite/glue spray (used for spraying conductive coatings on plastic boxes?) that's good for this. This stuff I believe: http://www.rapidonline.com/mechanica...coating-30090/ __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

21st Feb 2013, 1:47 pm	#7
brenellic2000 Octode Join Date: Aug 2006 Location: Rye, East Sussex, UK. Posts: 1,647	Re: Graphite for membrane key-pads! Thanks lads... I think a one litre can might be a tad OTT!

21st Feb 2013, 2:36 pm	#8
Vicboduk Hexode Join Date: Aug 2007 Location: S.W. London, UK. Posts: 416	Re: Graphite for membrane key-pads! How about this from CPC. I'm not an "e-bay" person but I suspect if you search for "keypad repair kit" you may find something cheaper. Vic

21st Feb 2013, 5:40 pm	#9
camallison Heptode Join Date: Feb 2013 Location: Yarm, North Yorkshire, UK. Posts: 535	Re: Graphite for membrane key-pads! I have successfully used this in the past. Colin

22nd Feb 2013, 3:09 pm	#10
brenellic2000 Octode Join Date: Aug 2006 Location: Rye, East Sussex, UK. Posts: 1,647	Re: Graphite for membrane key-pads! I have always shied away from using graphite powder on membranes in case it 'falls off and shorts' - does it stick satisfactorily to the rubber and ipso facto, my fears needless? Barry

23rd Feb 2013, 10:44 pm	#11
MrElectronicman Heptode Join Date: Feb 2011 Location: Washington DC, USA Posts: 619	Re: Graphite for membrane key-pads! I found a repair kit (in the USA) for one of my keypads. It was some sort of paint, much like the heated rear window repair kit used for cars. Worked for a couple of more years. __________________ David