Sinclair ZX80 / ZX81 / Z88 Forums

Hello there! I'm a collector from Virginia! You may know me if ya hang around Lemon64 and AtariAge. I've got one NTSC Zx81 and a TS1000 and I'm trying to figure out if it would be possible to mod the system. To run off batteries... and give it composite video...

Papa_Bear wrote: ↑Fri Apr 07, 2017 3:14 pm Hello there! I'm a collector from Virginia! You may know me if ya hang around Lemon64 and AtariAge. I've got one NTSC Zx81 and a TS1000 and I'm trying to figure out if it would be possible to mod the system. To run off batteries... and give it composite video...

Hello and welcome!

You can get a composite mod board from Sell My Retro (http://www.sellmyretro.com/category/ret ... clair-zx81) called the ZX8-CCB, although this one is currently out of stock with more to come shortly I believe, or you can get the ZXVid which is in stock.

Not sure about how you would do it but I have seen a video on YouTube of someone who turned a zeddy into a laptop with a small LCD screen and batteries so I guess it must be possible! Link from here viewtopic.php?t=1636

Lardo

I've actually been thinking about sticking either the zx or ts into a Speak and spell case.... Right amount of buttons too. I'd just need a proper screen and batteries for the thing. I've ready that making new copies of some of the chips to cmos greatly reduce power consumption

The 74 series of TTL chips have evolved into many different types. I have a ZX80Core made by Pokemon that used 74HCT chips that run at 75mA rather than the 300mA the original ZX80 took. I bought a lithium battery power pack from Radio Shack and have used it to run the ZX80Core

I'm gonna mess with my TS1000 I'm going to see if I can follow a blueprint of the keyboard and see if I can make a replacement myself that isnt nearly as horrid And see if I can find a composite video mod for it.

Would be great to see pictures when your done!

I love the already made ZX8-CCB which is going to have on the new model a sync generator to keep screen from scrolling at SAVE/LOAD and other instances... great for ZX80 I bet.

Papa_Bear wrote: ↑Thu Apr 20, 2017 9:51 pm I'm gonna mess with my TS1000 I'm going to see if I can follow a blueprint of the keyboard and see if I can make a replacement myself that isnt nearly as horrid And see if I can find a composite video mod for it.

Welcome aboard! Good luck with your project and keep us up-to-date!

Still waiting for the tac switches to come in. Got the prototype board at least and its the right size. This will be ugly as sin when it's done lol

Hi all.

My Timex 1000 currently has a Composite MOD on it, Just Soldered to the PCB. I Purchased it like this, with a Gold Plug Drilled into RIGHT Side of Top Case! I will see if I can Upload Images on this Site shortly.

I was also wondering if the ZX Speccy Composite MOD will work on the ZX81 ??? As both Machines use what look like the Same RF Modulator???

Will have a look, Watch this Space!

Darren in OZ

Hi again ZX81 Fans.

OK, I had a look at this COMPOSITE Out on my Spare Working TX 1000 (ZX81).

This is an "ISS 3" Mainboard.

The Gold Socket, I assumed was Composite Out, is actually an additional RF Out. Re-routed around the Modulator for Some reason, maybe for the use of a 2nd TV (2 x TV's in use at Once jobby) or something???

Anyway, this is of No use to me, so I De-Soldered it and Removed the socket.

Something of interest though, this unit has a RESET Button, that does WORK!

If anyone out there wishes to Install a Reset Button, this is simple, just 2 x Wires to a Press Release Button Switch.

Turn your ZX81 Mainboard Over, and Looking at the Under-side of the Mainboard, the Negative Wire is connected to the Bottom / Lower Earth or Ground on the RF Casing Frame, the Pin that is Soldered to the Mainboard closest to the EAR MIC and 9V Plugs (See White Wire in Attached Picture).

Looking at the Under-side of the Mainboard, the positive or other Wire, is Soldered to the Z80 CPU.

Look for the Left Hand Side Row of Pins on the Z80 CPU, this Wire is Soldered to the 6th Pin up from the Bottom (See RED Wire in Attached Picture). (Can't Up-Load Image!!!)

I hope this is useful to someone.

Enjoy,

Darren (amigaman07)