I enjoyed that. I have a ZX81 to look over at some point, and will do the composite video mod, though just for good measure I might make it out of stripboard just to be DIY :)

Lol, I liked the Edgar Wright style desoldering montage :)

@leesmithsworkshop

2 жыл бұрын

Thank you, I was in the edit and needed something for that part so decided to give it a try and it turned out ok.

Interesting computer and good repairing.

I bought the original ZX80 in kit form to build in my technology class but once assembled it would not ouput a signal so I sent it to the Sinclair kit fix department and after about a month it came back working with a few componants replaced and then about 3 months later a brand new kit arrived, my dad called Sinclair to tell them about it and they told him to keep the kit for spare parts, I never did build the second kit but sold it in 2014 still unopened along with the original kit.

Came over from Canada...that's a long way. Bell Fruit in the mid-80s used a graphics system in their digital fruit machines which was developed for a futuristic game console designed to compete with the Amiga but never made it to market. The successor to that system became the Atari Jaguar.

@leesmithsworkshop

Жыл бұрын

came over to visit family for reasons.

That was a good fun video. I've never used a ZX81 so I learned quite a bit from you, thanks ;)

@leesmithsworkshop

2 жыл бұрын

It did struggle a bit and missed out quite a lot of video when I thought something was wrong.

I’m not sure how much cleaning, paint or stickers could make that massive case and offset keyboard look good! You could put a screen in with all the spare space!

@leesmithsworkshop

2 жыл бұрын

I know, but then it's not something that excites me enough that I want to spend time and money on it

Having a zx81 in a custom case back then must have been like living in the future! What a great way to bond with your son, hardware hacking a computer. Brilliant video again Lee!

@leesmithsworkshop

2 жыл бұрын

Thank you for the working zx81 and composite mod pcb, I couldn't have made the video without your help.

Recommendation for desoldering. Use low melt solder. Mix it in with the leaded solder. It makes it much easier removing parts. Just don't use it for soldering.

Brilliant. So glad you got it working again Lee. Made me smile when the “K” came up on the screen; many good memories 😃

@leesmithsworkshop

2 жыл бұрын

Thank you, I had a fun few weeks learning how it worked and solving the keyboard problem. After this a friend at my office gave me two more to look at and one has a fpga ula to try out.

These old power supplies were desighed like that. The transformer puts out more voltage because it depends on the line voltage and today the line voltage is higner than it used to be. If you replace the voltage regular with switching module, you can keep the transformer, the switching module will handle it with no problem. The expansion connector looks very fragile. I'd consider to replace the bare wires with a piece of stripboard to make it more solid.

@leesmithsworkshop

2 жыл бұрын

I doubt I will use this so really not going to worry about it and if I did spend money it would be on a fpga ula with memory expansion anyway,

@JendaLinda

2 жыл бұрын

@@leesmithsworkshop Also there's plenty of room inside the case so you could use one of those cheap adjustable buck converters from China. These are very handy so you should get few of them anyway.

@leesmithsworkshop

2 жыл бұрын

@@JendaLinda I have a few types and was thinking of using usb to power.

I knew that was a ZX81 because I had one the same they use to sell keyboards to replace those nasty membrane things, I used to draw pictures using the graphics mode on the keyboard loved it.

@leesmithsworkshop

2 жыл бұрын

Yes a DK Tronics keyboard. What case did you put yours in ?

@OldPoi77

2 жыл бұрын

@@leesmithsworkshop I am fairly sure it was the same one, it hit in my memory right away when I saw the thumbnail.

@leesmithsworkshop

2 жыл бұрын

@@OldPoi77 someone else has said the same thing, so perhaps it was all sold as a kit.

Hi. You lowered the voltage for the computer below 9V. That can be problematic, as 9V is not used by the ZX81, but is sent to the expansion bus for external expansions. I believe the Memotech 16k RAM pack you have attached needs the 9V, so maybe it will be unstable or destroyed, if you only supply 5V.

If you get to try that loading on a CRT you'll see the black and white patterns but on an LCD it tends not to sync up quick enough.

@leesmithsworkshop

2 жыл бұрын

I did want to try this, but my crt tv is at home packed away.

It goes blank as it enters FAST mode, which makes it faster (but the screen goes black). I've tried a version of this when you don't do this. and it's a LOT slower in SLOW mode :)

@leesmithsworkshop

Жыл бұрын

I remember you telling me when while I was making the video.

@WhatHoSnorkers

Жыл бұрын

@@leesmithsworkshop It's a clever trick, if you know it's going to do it. Otherwise it's a bit alarming!