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Zx81

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wgoodf

Experienced Member
Joined
May 7, 2006
Messages
58
Location
edinburgh
Well i finally found a ZX81 to buy at a good price too.
buttons 1 through 4 don't seem to work, but the rest is fine. It also came with a printer and two rolls of that silver thermal paper.

Only 1K as no ram pack with it, but a good wee lot i think, a couple of the original tapes too.
Can't wait do do some 1k gaming.

I take it that there is nowt that can be done about the keyboard problem, as its all glued down, but has anyone played with a keyboard repair on a ZX81?
Or the Timex Sinclair 1000 for that matter if that had the same membrane keyboard instead of the rubber chicklet type.
 
I dont have a zx-81, but I've been hoping to get a timex sinclair 1000.
As most of the members on the forums have stated, most of the early sinclair computers had bad membrane keyboards.

Great find! good luck and hope you fix it up soon.
 
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Good score, especially the Screen Printer! I hate to use the R-word, but you really don't see many of those around these days. Could you perhaps post a pic? (Most of us here have probably never even seen one).

--T
 
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I think there are resources for restoring or replacing the membrane, but it was a few years ago I read about it. Search around in Sinclair/Spectrum newsgroups etc. If you don't care about physical condition, it might be a fun project to build or adapt your own keyboard instead of the original one. Back in the 1980's, a lot of people did all sorts of such hacks to the ZX-81, also internally adding RAM expansions. Some even managed to squeeze in a 16K expansion into the original case!
 
risky, but on my old zx80 years back before they were ***@@@RARE@@@***
I managed to just peel off the membrane keyboard, you can repair the contacts with silver-loaded rear-heated-window repair paint, then carefully evo-stik the stuff back together again.

As it's a complete half-row, check the circuit diagram and look for a faulty diode, or a break in the pcb/plating through first before you rip anything apart.

I eventually got fed up of the membrane, and hooked up an old keyboard to mine, threw away the case, wired it up to reed relays on my train set, reduced it's value to truly nil, then it died anyway, so it went in the bin about 10 years ago!
 
I've owned a TS1000 (ZX81 clone) for many years. The membrane keyboard is probably fine. The ribbon cable that connects it to the system is probably the problem. It wasn't a true ribbon cable; it resembles plastic with some traces on it. The plastic gets brittle due to the heat in the system unit.

If you remove the board from the case you can 'simulate' keys with bare pieces of wire going into the keyboard ribbon cable connector. Map out the 4x10 keyboard, wire up a suitable replacement, and you are all set.

(I've mapped it out before and have found a C64 spare parts keyboard, but I haven't wired mine up yet. It's been 15 years since I found they keyboard, why hurry?)

After I'm done mastering the PCjr universe I'm going to turn my attention to the ZX81 .. now there is a seriously hackable machine.
 
If the plastic ribbon with traces on it is damaged, I personally found it practically impossible to repair by my means. The ribbon can't be cut higher up to start fresh because then it is too short. It can't be soldered to or glued to. I didn't try conductive pen because I didn't have any, but the ribbon was far too gone for that anywasy, methinks.

IIRC, (But not sure) The keyboard is 4*10, but the matrix is split down the middle, so it's sort of 2*5*4. This would make perfect sense if the keys 1-5 were broken but they aren't, so never mind.

I tried to repair my keyboard. I dismantled an old switch keyboard, sliced all the traces and wired a new matrix to the back, then soldered a ribbon cable to the original keyboard input pins. Of course it didn't work first time, and I never got round to sorting it out, the project was put on the shelf. Unfortunately when I came back to try again, the ZX81 had died (A replacement would be nice, hint hint to anyone with a spare ;))

I later found out that later spectrum models up to the Amstrad/Sinclair +3 use a very similar matrix, and an identical connection. It would be a small effort to plug it in and then write on what buttons what does what.
 
i had read before that the keyboard ribbon was a likely fault and if so, its kinda beyond repair - well at least with my very limited skills.
but i cant see myself doing much in the way of programming so i think i should cope.

all i really need is a 16k ram pack and a copy of the super high rez game monster maze 3D - anyone remember that one?
it was truly a stunning game - how they managed to do it was beyond most folk of the time, but the graphics were indeed high rez.

as far as pics - yup i will get around to posting them, but it may take a week as the computer is really a xmas present to me - so once i checked the machine working i had to re-box it and give it back to the wife to wrap for me.

yup - sad aint it!

but once opened and played with - printer pics will follow.
 
The ZX81/TS-1000 "keyboard" was a nightmare. I have painful memories of this little box, but you still have to acknowledge it for what it was: the first true low-cost computer for the masses. It was extremely limited, in some aspects downright laughable, but I guess that's part of its charm in retrospect.

The ribbon "cable" connecting the keyboard was nothing more than a cheap foil that becomes brittle with age -- a disastrous decision to cut manufacturing costs. If your ZX81 still has a working keyboard, you'd be well advised to leave that connector alone, let alone jiggle the box...

My TS-1000 constantly lost keyboard contact, and I ended up cutting the foil down to a clean edge each time, often repeating the procedure after snapping it while shoving it into the socket. Inevitably, I ran out of connector at some point and was left with a useless stub. I replaced it from with a donor keyboard from a ZX81 I found (much to my surprise) at flea market for a laughable price. It was only afterwards that I realised the ZX81 infact worked -- silly me.

The ZX-Team in Germany (see the link in a previous post) sold replacement membrane keyboards, but when I inquired several years ago they were already sold out. Maybe you'll have better luck...

--Roland
 
Being a big briish comp geek, I know alot of the software for it. Yes, I've heard of monster maze 3d, there's a page for it on wikipedia.

I'm going to keep my eyes peeled for the timex sinclair 1000, and maybe even the zx81
 
wgoodf said:
Well i finally found a ZX81 to buy at a good price too.
Click to expand...

I'm still looking for one. They are a lot less common and more expensive than I thought they would be, at least here in New Zealand. I can only assume that being small, light and inexpensive in the day, they were trashed without a thought as opposed to larger, more expensive micros which may have sat in the garage or loft for years.

Anyway, one will surface sometime soon, I'm sure...
 
They are uncommon here in Sweden too. You don't see them on swedish auction sites a lot. They are more common in the UK but shipping from the UK, even within Europe, is really expensive so... :(

I just sold one ZX81, just the computer and the power supply for 360SEK (around €38 or US$55). So they are worth something to some people :)

// Z
 
see, price is a funny thing.

mines cost £10 - so $20 thereabouts and it was untested and without the RF lead, and i thought that quite a good deal considering that it came with manuals and the printer.

had the lot i bought been confirmed as working and without issue, i would have expected it to go for £40-£50
 
LOL! That's the first time I've seen one of those thermal printers in action.

Technology has indeed come a long way.
 
it seems that they are not actually thermal printers, but 'spark' printers.

well so says wikipedia!

-

and yes, there is a smell - kinda like old motherboards when you open the case.
 
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