TI99/4a (corrected) Keyboard (membrane) Rebuild.

Discussions about Sinclair ZX80 and ZX81 Hardware
vwbz80a
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TI99/4a (corrected) Keyboard (membrane) Rebuild.

Post by vwbz80a »

Afternoon reading Dan Moore's post I gave mine a closer look. Boo!
It WAS a membrane type. :cry: And it was no longer working with my TS1000. :cry: :cry:
Tore it apart. The PCB seamed usable as did the key mechanisms.
Experimented with strips of aluminum foil, then went looking for some copper foil ...... none found.
Found small sheet of copper .005 thick. Cut to 1/4 inch x 5 ? Strips. Packing tape,clear, for holding to the PCB. The key mechanisms not strong enough to push metal strips into the PCB traces. So reworking the key mechanisms with a solid pin.
That's were I am now. Cutting .160 inch steal pins .700 inch long. 41 pieces. :| :|
Last edited by vwbz80a on Sun Feb 18, 2018 9:24 pm, edited 2 times in total.
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gammaray
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Re: TI99/4 (I think) Keyboard (membrane) Rebuild.

Post by gammaray »

Wow. Do you have time to show pictures? Yes I am excited by every design project!
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
vwbz80a
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Re: TI99/4 (I think) Keyboard (membrane) Rebuild.

Post by vwbz80a »

gammaray wrote: Mon Feb 05, 2018 4:09 pm Wow. Do you have time to show pictures? Yes I am excited by every design project!
https://www.dropbox.com/s/3g92kcwqdqy3r ... 4.jpg?dl=0
vwbz80a
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Re: TI99/4 (I think) Keyboard (membrane) Rebuild.

Post by vwbz80a »

This is my scan of keyboard pcb & top plastic membrane.
https://www.dropbox.com/s/kw7ebsb3m1fc5 ... 2.jpg?dl=0
;)
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gammaray
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Re: TI99/4 (I think) Keyboard (membrane) Rebuild.

Post by gammaray »

What are the copper strips for if you have the membrane and PCB?
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
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gammaray
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Re: TI99/4 (I think) Keyboard (membrane) Rebuild.

Post by gammaray »

I think you have the later '/4A keyboard since they tried to save money on production.

The '/4 keyboard was Chiclet type.
1979_TI-99-4.jpg
1979_TI-99-4.jpg (115.03 KiB) Viewed 5525 times
Charles
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
vwbz80a
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Re: TI99/4 (I think) Keyboard (membrane) Rebuild.

Post by vwbz80a »

gammaray wrote: Sun Feb 11, 2018 6:20 pm What are the copper strips for if you have the membrane and PCB?
Copper strips are my attempt to replace the upper plastic /carbon tracks. 😉
(Short answer)
vwbz80a
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Re: TI99/4 (I think) Keyboard (membrane) Rebuild.

Post by vwbz80a »

gammaray wrote: Sun Feb 11, 2018 9:52 pm I think you have the later '/4A keyboard since they tried to save money on production.

The '/4 keyboard was Chiclet type.

1979_TI-99-4.jpg

Charles
Correct. No Chiclet keys.

There is a Mitsumi # on the pictures.
The keyboard was a surplus item purchase back in '86-87. (cheap) :D
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gammaray
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Re: TI99/4 (I think) Keyboard (membrane) Rebuild.

Post by gammaray »

https://www.sinclairzxworld.com/viewtop ... =10#p29799

The keyboard map to adapt to ZX81...
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
vwbz80a
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Re: TI99/4 (I think) Keyboard (membrane) Rebuild.

Post by vwbz80a »

gammaray wrote: Fri Feb 16, 2018 12:47 am https://www.sinclairzxworld.com/viewtop ... =10#p29799

The keyboard map to adapt to ZX81...
Just looked it over. Used the same diagram/table ..
Not recommending this approach. NOT!!!!
But I moved the cap tops over on the bottom row by 1 to the right .
[ shift ] ,z,x,c,v,b,n,m,
https://www.dropbox.com/s/kxfkwq15bx8ej ... 2.jpg?dl=0

Removed extra key mechanisms .(plastic plunger).
Traces now are correct. I'm thinking.😁
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