Timex Sinclair 1000 5 keys not working

[falter]

Hi guys,

I have a Timex 'doorstop' that has been sitting around forlornly so I decided to fix it up. Basically it works fine except the keyboard, with the famously fragile ribbon cable. Sure enough on examination it became clear the traces on that cable were broken in a few places. My solution was to snip off the last quarter inch of both cables and reseat. Boom! Half the keys were now working. I then took a second look and realized the 8 pin cable had a break at the bottom also. Since I couldn't cut down to there, instead I took a very small piece of copper wire and taped it across the break. Voila. All of my keys work now *except* 1-5. So I had a look at a key matrix here:

http://forum.tlienhard.com/TS1000/www.mainbyte.com/ti99/keyboard/keyboard_schematic.jpg

What I know right now is that the Function key does in fact work. But 1-5 do not. To me, if it were a trace problem, Function would be out, correct? (I have to get better at reading key matrices). Is it possible I just have 5 dead keys? Literally everything else works.

I'm only doing this for the fun of it and learning. I know I could simply buy another for $10 off Ebay.

 

[Eudimorphodon]

Years ago I came into a box of those doorstops (a mix of TS1000s and ZX81s) and they all had similar problems to yours. (And I got one of them working the same way, snipping a bit off the ribbon end.) Does indeed seem to be a common problem...

In any case, I wonder if the key matrix you're referencing here isn't right? There seem to be some other matrix drawings floating around out there that suggest that keys 1-5 are all there are on that row. Example:

http://fetrmartin.free.fr/ZX81/zx81_imp8B.gif

If this diagram is to be believed it's the line going to A11 that's the problem, and that jives with the bigger schematic in this .pdf:

http://www.qrp.gr/microwave/giannopk/zxcomputer/zx80.pdf

(That's for a ZX80 not 81/TS1000, but they're all the same.)

Actually, that one you linked to seems to reference keys that aren't actually on a TS1000? (IE, I don't think it has a separate ctrl and fnc key?) The URL has the word "ti99" in it...

 

[falter]

Ok that explains it. My patch for the a11 line didn't work. I fixed it, but then the cable broke further down. Now it's so short I can't manouevre it into the ports. I think we are done here.

 

[Eudimorphodon]

Heh. You could do what most truely dedicated users of those systems did and wire up a better keyboard, I guess. Or just huck the doorstop in a box to use for spare parts. It has a perfectly good Z80 in it.

 

[roberttx]

It's a bit late to help the OP, but when I lived in England I had good luck fixing ZX81 & Spectrum ribbon cables with the conductive silver "paint" that they sell at auto parts stores, for repairing rear window defrosters.

You just need a very fine brush (from an art store) a steady hand and a little patience.