Keyboard membrane repair

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centaur_qlf
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Keyboard membrane repair

Postby centaur_qlf » Sun Jan 23, 2011 9:33 am

I bought a QL and then acquired several used ones. Keyboard failures weren't under the keys, but at the fold in the membrane leadouts. I was able to link over the breaks by drilling fine holes and connecting a bridging link of fine wire with conductive paint. As more broke and contact at the connector became unreliable, I felt that a replacement membrane might present the same fault. I found some strip ribbon cable with the same pitch as the connector, cut the leadouts back, bonded the strip cable to the remaining membrane, and linked the connections as above. Exposing the conductor at the other end, and they fitted with good connection. A little fiddly, but I don't mind that sort of thing to get utter relibility. I think that I put a bit about it in Quanta Magazine at the time. One of the QL's came with a separate Rainbow keyboard and that has been completely reliable, with the advantage of a numeric pad.

ADDITIONAL NOTE Please see also my post "Membrane repairs - further" for a better method developed later. Nowadays new manufacture membranes are available which may prove reliable, if they survive the post. (see Rich Mellor's remarks). It may also be difficult or costly to get one in a remote area. Also a repair could be quicker if bits are to hand.
Last edited by centaur_qlf on Sun Jan 30, 2011 10:52 am, edited 2 times in total.


dex
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Re: Keyboard membrane repair

Postby dex » Sun Jan 23, 2011 11:56 am

Just buy a new membrane form Sintech http://www.sintech-shop.co.uk/shop.php, maybe RWAP also has these!
They are a new production by Tesla Jihlava http://www.ttklavesnice.cz/indexen.php, much better than original, of high quality material, not so rigid as original, cannot crack by bending as easily as the original.


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robheaton
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Re: Keyboard membrane repair

Postby robheaton » Sun Jan 23, 2011 3:18 pm

RWAP do sell replacement membranes - http://rwapsoftware.co.uk/sinclairql.html#SPARES
Not just for the QL either, they are available for the ZX80 & ZX81.

They are also for sale on http://www.ebay.co.uk & http://www.sellmyretro.com


Although replacing parts isn't half as much fun as repairing them! Perhaps centaur_qlf just wanted the challenge!!


Current Retro Hardware :-
ZX80 Clone, ZX81 + Chroma + ZXPand + Zeddynet, Just Speccy 128, BB Sinclair QL + Trump Card Clone, Aurora + Super GC + QubIDE.
BBC Model B 32k + Datacenter + Z80 Tube, BBC Master 128k + Datacenter & 6502 Tube.
Commodore 64.
centaur_qlf
ROM Dongle
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Re: Keyboard membrane repair

Postby centaur_qlf » Sun Jan 23, 2011 6:26 pm

I did make clear that my reason for repairing was because I felt that the old production available as spares at that time might be no better and I preferred an absolutely reliable repair.


Dave
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Re: Keyboard membrane repair

Postby Dave » Fri Jan 28, 2011 11:43 am

The other cause of membrane failure is oxidation of the strips (or maybe degredation caused by skin acids) - the solution to this seems to be to trim the bottom 3-4mm of the ribbon with a scalpel or sharp scissors, then clean it with rubbing alcohol to remove any oils.

I personally would just buy a new membrane, but my experience of ordering one from the UK was that by the time it arrived in TX it was creased - this was in 2004 or so, and the membrane seemed to be of the original 1984 type, and "crispy" ;)


RWAP
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Re: Keyboard membrane repair

Postby RWAP » Fri Jan 28, 2011 5:53 pm

Dave wrote:The other cause of membrane failure is oxidation of the strips (or maybe degredation caused by skin acids) - the solution to this seems to be to trim the bottom 3-4mm of the ribbon with a scalpel or sharp scissors, then clean it with rubbing alcohol to remove any oils.

I personally would just buy a new membrane, but my experience of ordering one from the UK was that by the time it arrived in TX it was creased - this was in 2004 or so, and the membrane seemed to be of the original 1984 type, and "crispy" ;)



I didn't realise the postal system would still deliver these after 10 years or so :lol:

The latest membranes are manufactured either in 2010 or even 2011, using much better materials than the originals, so should hopefully survive the test of time better.

I ship mine in A3 sized cardboard envelopes - yet the postal service have still been known to fold them up to fit through a normal sized letterbox!!



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