I'VE GOT MY ZX-81!!!!! =8-D

[yerzmyey]

Well. I've got it at last.
ZX-81 16Kb.

As I wrote in another topic, sadly it appeared to have broken keyboards (last 5 keys don't work) but I hope to replace it or something.
Anyway it works OK more/less, it loads progs and so on.

Btw, my question is about TV-set. Do You have any problems while connecting ZX81 into very new TV-sets?
I connected it to such and it shows distorted screen - dark waves, looks like the power-supply is broken, but it isn't.

I connected it then into pretty old TV-set and the screen is normal and stable. Weird. Any suggestions about it?

Greetz,
Yerz
The Proud Owner of ZX81 16Kb

[RWAP]

Great news !

The problem with a TV is an age old problem - modern TVs expect a strong signal to allow it to automatically tune - it therefore struggles with the poor signal from the ZX81.

[Andy Rea]

It sounds like the back porch problem, if your zx81 has the older ULA (ula 2c210e , good should work on most tv's, ula 2c184e , bad might work on some tv's) it does not produce a back porch, if it has a newer ULA then it does and should work alright on any tv, FYI the back porch is a small portion of the tv signal imedialty after the Hsyncs that the TV set uses as a reference signal to the BLACK level on old ULA the signal returns ti white imedialty after the Hsync and it is that that confuses the tv.

here's an old thread.
http://forum.tlienhard.com/TS1000/www.t ... 795758.htm

and here is the circuit i still use over a year on in one of my zx81 that has the old ULA.
http://homepage.ntlworld.com/deborah.cl ... idmod3.jpg

Regards Andy

[yerzmyey]

Many thanx, guys.

Well, I already ordered extremly small TV-set, very cheap one, so I expect it's based on old circuits and will be fully analogue (hope so) and I hope it will work OK with the ZX81 although it's new (but it's so cheap that I suspect it's based on some extremly simple technology. Maybe Chinese stuff or sommit?). We will see.

Bigger problem is with keyboard sadly. I hope I will solve it somehow too.
The selling guy said the comp is fully in working order but... Well, now it's kinda too late.

[gus]

Hi and congratulations !!!!

Maybe you already know it and of course all the other people on this forums knows about it too... but who knows ????

Well some tiem ago I bought one TS1000, the seller tell me the keyboard is broken... I disasembled it and saw that the "flat cable" ? of the keyboard is broken... I just take a cutter made a clean straight cut then connect it again and problem solved... all is working now

Maybe you can check it on you new baby

Gus

1 picture = 1000 worlds

[yerzmyey]

Hm, yes - seems like a good idea too! I will check it out then.
Thx!!!

[sirmorris]

Are you going to be modding your machine? Or keeping it 'virgin'?

[yerzmyey]

Oh, this is (just for now hopefully) my the only ZX81.
In this case I have to leave it in original state. Of course I mean the comp, not additional interfaces. 18Kb ram-pack I have already.
Anyway the problem is that ZX81 and its additional hardware are pretty rare here. So I don't know when will be my next occasion to get some ZX81 stuff (joystick interface would be nice).
I will try to buy another ZX81, hopefuly fully-operational this time (with working keyboard, hehe).
Greetzzzzz.

[yerzmyey]

I was studying the problem.
According to this http://www.rwapsoftware.co.uk/images/ZX8I.pdf
my keyboard should be OK but it can be "11" string broken.
All 5 last keyz are on da "11" string.
Hm.
I will have to check it out once again.

[yerzmyey]

About the TV signal - thank You, guys, for Your statements.
You were right of course, now I bought the small TV-set (5,5" - http://photos04.allegro.pl/photos/orygi ... /373015539 ) and it works perfectly.