Sinclair ZX80 / ZX81 / Z88 Forums

Hi res won't work with the original 16k ram pack, by the way. The mod for that is here...
https://msknight.com/bbc/zx81-rampack.html

You might want to use a 1K Hi-res game to see if the ULA is capable of WRX high res before you do the RAM upgrade. I put a little about that here - https://msknight.com/bbc/zx81-ram.html I went slightly bonkers trying to solve what I thought was a RAM timing issue, when in fact the ULA wasn't up to ...

To use the RGB to HDMI, you need to note a couple of things which you might already be aware of, but I didn't see it in your post... 1) The RGBtoHDMI needs an analogue input board. 2) The input to the RGBtoHDMI is taken from the composite output before it goes into the UHF module and not the output ...

I don't think there's one easily available. However, Ginger Electronics does some very nice insertion boards which he did sell to me separately, and I used whatever wire I preferred. You might want to consider putting a small tab on the top of the small boards to make them easier to pull out if, lik...

329 ohms.

Umm... I don't know. It's somewhere in the wire wool for cleaning the iron. Too small. I think I've got another of that type so I'll check when I can dig it out.

Stuff it. I couldn't resist. No, removing the resistor didn't solve it.

It does seem that there is a resistor installed on the one that doesn't work, against the one that does. I'm going to try removing that in a day or two, and see what happens.

Paul - How do I check the capacitance please? Did you mean resistance? Do I really want the multimeter using capacitance tests by putting voltage into the card?

Apologies for my newbieness.

Thanks - I'll give all that a check.