I just buy my first ZX80 and I am more than happy.
Motherboard is issue 3. I get this as untested and I am looking forward to make this beauty healthy again.
There are a special schematic for issue 3?
My zx80 have marked as USA but this is UK keyboard am i right?
This thread may be useful to you...
https://www.sinclairzxworld.com/viewtop ... f=7&t=3266
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The different modulators (normally VHF for the USA and UHF for Europe) only affect the allocated frequency for a (nominal) ‘TV channel’ (in Europe its channel 36). This does not affect the 625 line / 50Hz or 525 line / 60Hz video format. But obviously for the VHF modulator, if a using RF/aerial connection, your TV must be able to receive VHF channels.
On the keyboard, as far as I know, there was only ever one layout.
https://www.sinclairzxworld.com/viewtop ... 894#p36894
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
Iss 3 ZXVid
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
I'm sure Mark will be along with some sage advice on how to proceed( he saved my 80 from the scrap pile).
A few observations.
The ceramic caps and resistor around the EAR?/MIC sockets seem to have been added as a rudimentary hi pass filter to improve LOAD/SAVE which I have always found unnecessary as the 80's output is much louder than say the 81, and I never had a problem with tape LOAD/SAVE although now I use the ZXpand with my 80.
The cap on the power socket I would suggest is just for removing any spikes on the supply line.
I notice also you have plugged it into a modern LG LCD TV. I would be surprised if you got a picture of any sort as without modification the humble 80 really is really more used to being used with a CRT TV.
With a Modern LCD set I could never get a picture through the modulator so in the end modified it for composite output.
I look forward to seeing this little gem being fully restored please keep us informed of progress.