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Timex/Sinclair 1000 not displaying correct key pressed.


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#1 gs80065xe OFFLINE  

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Posted Fri Apr 12, 2019 8:59 PM

A boxed Timex/Sinclair 1000 I recently purchased arrived today. I decided I wanted to see something like what the folks in the UK had when I was using my Atari 800.

 

The seller said it was untested. But it appeared to have never been used. First I tested the 9VDC power supply with an analog and digital meter. It was reading about 11 - 12VDC on the analog meter. Higher on the digital. About 14V. But they both read higher than rated on some other DC adapters I have. So I plugged it into the PC without connecting to the TV.  Well, there was no sound, smoke or heat right away. So I hooked it to the LCD TV. Turned it on. First wasn't sure it was working. A lot of interference on the TV. Even in the sound. So I muted that. The K appears in the lower left. I tried typing some keys. But what I pressed did not translate to the screen. So I thought maybe keyboard. But then I pressed P, which should automatically display the PRINT keyword. It didn't print PRINT. And each time it was different variation of a 5 character word. So is this a bad keyboard or something at the board level?

 

Thanks,

Glenn

 



#2 DragonGrafx-16 OFFLINE  

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Posted Sat Apr 13, 2019 2:27 AM

Not really what they used over there. That would be the ZX Spectrum... the 1000 was just too basic to play games or anything at all really.

Edited by DragonGrafx-16, Sat Apr 13, 2019 2:28 AM.


#3 mr_me OFFLINE  

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Posted Sat Apr 13, 2019 5:03 AM

The timex sinclair would be comparable to the zx81, the precursor to the popular zx spectrum.

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Those old unregulated ac adaptors will read high without load. Are you saying only the 'p' key responds.

#4 Nukey Shay OFFLINE  

Nukey Shay

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Posted Sat Apr 13, 2019 5:09 AM

Not interpreting correct keypress...bad Ram?



#5 monzamess OFFLINE  

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Posted Sat Apr 13, 2019 6:13 AM

Try https://sinclairzxworld.com. There is still an active ZX81/TS1000 community on this planet, and that is where they hang out.

The ribbon cable from the keyboard to the motherboard dries out and cracks so even brand-new-in-box units are likely to have bad keyboards. Luckily you can buy reproduction replacements and even upgrades. For that, try https://www.sellmyretro.com

Edited by monzamess, Sat Apr 13, 2019 6:17 AM.


#6 JamesD OFFLINE  

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Posted Sat Apr 13, 2019 11:12 AM

The ZX-80/81 were actually quite popular in the UK for a while since they were the most affordable machines until more powerful computers like the Spectrum came out in 1982.
The TS-1000 sold over 1 million machines in a single year in the US, but people in the US had higher expectations. 
I found a TS-1000 at a yard sale for $10 in 1983, only 1 year after they came out.  No I didn't buy it.

The keyboard membranes tend to fail, but keys just stop working when that happens.
If the input is changing, that's going to require a look at what is happening on the buss when you type a key. 
Sounds like noise on the buss and the voltage levels of signals are borderline.
That is totally a guess though.  It could just be a bad chip.  Luckily the original ZX-80 was mostly off the shelf parts, which is why there were so many clones.

The video output on the one I had was crap.  There are several pages dedicated to that.

It seems like a lot of work for the machine.



#7 carlsson OFFLINE  

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Posted Sun Apr 14, 2019 12:14 PM

The power adapter probably is linear which means it is fairly normal to get 12-14V without load, down to 9-10V once you have a load.



#8 RWAP OFFLINE  

RWAP

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Posted Tue Apr 23, 2019 4:12 PM

Getting the wrong keyword when you press a key is not a fault of the keyboard membrane normally - it could be anything from a corrupt ROM chip to a leaky cap somewhere.  Asking on www.sinclairzxworld.com is probably your best bet :)






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