Sinclair ZX80 / ZX81 / Z88 Forums

The plug used on the ZX81 end should be a mono plug due to the design of the mono socket on the ZX81 board.

Mark

I'm not in london, but between bedford and cambridge, if you get really stuck and can't sort it, and are willing to come to me, I can try to help! a quick and dirty way of getting a composite video signal out to a TV with SCART or AV inputs is to connect the positive of a 100uf capacitor to the modulator input pin (the middle-ish lead), and feed the TV's video input from the negative of this capacitor (connect the ground of the zx to the ground of the TV input, obviously!) not really advisable to do it this way as it loads the ULA too much, but should be ok for a short (few seconds?) test to see if a K comes up! Try to get hold of an old black & white portable TV if you can! I have had a strange but very clever idea of a possible way to get a composite signal out without any internal modifications at all .... will post details on here somewhere if it works (when I get time to try it)

A new way of getting composite video, eh? Looking forward to hearing about that - I love it that there are always new discoveries to be made where the ZX80/81 is concerned!

..early tests of my idea are not good... I do have a 'plan B' which was a 'plan A' originally but couldn't get that to work at the time....oh, well...

Don't tell me, plan B is to bore a hole in the case so it is possible to connect a clip on probe

Mark

BORE A HOLE IN THE CASE??!!! No way!! (although one of my ZX81's has had that done to it by a previous owner....the poor thing ) Plan A 'MAY' yet work .. if it doesn't go unstable and can get the frequency response right (as near as I can)...

Thanks for all of your replies. I'm now better equipped: I have a logic probe, and an EasyCAP AV capture device (see http://goo.gl/qx87VM), which I'm told can output the video from the ZX to a modern computer.

Thus equipped, I've set out to implement the tests that 1024MAK described on 26 April - but encountered a version of the problem mentioned by PokeMon on 25 April: my KB connectors seem very brittle, with one of them half shorn. Is there a simple way of repairing these (conductive tape?)? If I want to disconnect the main board from the KB, can I lift the plastic mounts from the board?

Has anyone used anything like the EasyCAP before? If so, I'd appreciate any guidelines.

Finally, poglad - controlling your ZX81 by ear is one of the craziest things I've heard of in a long time: that's amazing!

Thank you,

Colin

Haha thanks. That EasyCap looks good. I've just ordered one - at that price I'm sure I'll find it useful for something!

Don't forget...you can't connect the easycap thing (I have had one for a few years, but haven't yet got round to doing anything with it!) directly to the zx81 TV out socket, as this is UHF RF out, you will need to 'tap off' a composite signal from the input to its modulator, through a capacitor of about 100uf 10v, positive to the modulator input point...or use a CCB or ZXvid module as they will 'clean up' the signal quite nicely..
as for broken membrane 'tails', only real cure is a new membrane, unfortunately!