Sinclair ZX80 / ZX81 / Z88 Forums

Just bought a Speccy off EBay. As far as I can tell it has not been opened before. The board is an issue 3B but it has a strange looking modification near the speaker which you can see in the photo. Doing a quick google shows that this is not standard on 3B boards. Does anyone know what it is or what it’s for?

That is the last official Sinclair modification to the power section. Details here on my blog

Mark

Thanks Mark, in your opinion was this done by the factory or by the owner? I am slightly concerned by the lack of solder in connection the top-right. I haven’t powered it up yet as I will need to perform a composite mod first.

Richard

Is the connection you are concerned about soldered on the underside? If yes, it’s nothing to worry about, as the holes are plated-through connections, so the tracks on the top and bottom are electrically connected together.

It may have been done in the factory (most likely), or when the board was serviced or repaired by a professional.

Mark

Yes, it seems to be soldered fine on the bottom. So I guess it's a good thing that it is has this mod even if it's a bit unsightly.

I did a quick test by holding the composite connector up against the wire that feeds the RF modulator and the case, and unfortunately I can see that I'm not getting the Sinclair Research text, so I suspect it has a lower RAM fault. I'll check that when I have some time.

Update on this Speccy - there was indeed a lower RAM fault - I replaced IC7 and everything is looking good so far

Mark