Sinclair ZX80 / ZX81 / Z88 Forums

Posted: **Fri Jul 27, 2018 1:56 am**

Hi!

As from the title, I’ve got an untested ZX81 at an ebay auction and I get this boot up screen?

What can be the culprit?

In the next days I’ll be able to measure with an oscilloscope the ICs, ma my thanks in advance!

Posted: **Sat Jul 28, 2018 9:33 am**

All the chips are socketed by the looks of it - if you have another zeddy try chip swapping to see if that helps.

Posted: **Sat Jul 28, 2018 10:46 am**

I don't have it, but I've bought a ULA - I think is the culprit - and when I'll get it I'll update the thread!

Posted: **Sat Jul 28, 2018 9:49 pm**

Is it possible that there is a composite conversion in it that needs pot adjustment? Maybe look under "RF Modulator" and see which circuit is in there.

Sinclair ZX80 / ZX81 / Z88 Forums

Bought untested ZX81 and got a black screen with a working cursor

Bought untested ZX81 and got a black screen with a working cursor

Re: Bought untested ZX81 and got a black screen with a working cursor

Re: Bought untested ZX81 and got a black screen with a working cursor

Re: Bought untested ZX81 and got a black screen with a working cursor