Sinclair ZX80 / ZX81 Forums

It would be helpful if you can list details of any chips used in this TV.

Mark

Hi Martin It may be possible to add a composite in in place of the RF input. After all, all TVs with a RF input convert this to some kind of composite signal internally. But it will not be very easy job without a schematic of the version that you have. I’m not sure if you noticed, but the versions i...

The transistor you used. In one of your other threads, I can see that it is marked BC108B. See no -B in photo just before this post, but yes I noticed that too. Chinese ripoff bought from eBay, AliExpress or so? I really don't understand why people save pennies on parts like this, as opposed to buy...

@RS232 Okay, I’ve studied your photos. The following points concerns me: The polarity of the electrolytic capacitor appears to be incorrect. As the existing capacitor may have been damaged, I suggest removing the existing capacitor and fitting a new one. What value of capacitor did you use? For this...

Both the ZX81 issue 1 PCB, and the ZX81/TS1000 issue 3 PCB have component positions for a variety of different video configurations. So you will see some positions where components have not been fitted.

Mark

What TV / monitor / display are you using? Have you tried a different TV / monitor / display? Before sticking a heatsink on the ULA, can you please take a photo of the lettering/numbering on the ULA. Is the ULA in a socket? Do you just own one ZX81? And as Andy says, which version of the composite m...

Welcome on board Jochen!



Hello Jochen. A warm welcome to Sinclair ZX World.

I’m glad to hear that you are enjoying the forum and finding it useful

Mark

Welcome on board Muttley Black!



Hello Muttley Black. A warm welcome to Sinclair ZX World.

Mark

Do you really think that we would burn you at the stake?

It’s your machine. As long as you use it and enjoy it, that’s fine with me

Mark

Welcome on board Glenn! :D :D :D Hello Glenn. A warm welcome to Sinclair ZX World. The 9V PSU supplied with these TS1000 / ZX81 computers is an unregulated type. So without the computer connected (‘no load’), the output voltage will be in the 12V to 16V range. This is normal. The computer will work...