ZX81 rebuild

Discussions about Sinclair ZX80 and ZX81 Hardware
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Andy Rea
Posts: 1490
Joined: Fri May 09, 2008 2:48 pm
Location: notts UK

Re: ZX81 rebuild

Post by Andy Rea » Fri Jul 06, 2018 1:13 pm

Cool stuff, us mad soldering iron weilding maniacs have to make do with whatever space we find ourselves in :lol:

Regards Andy
6 x ZX81, 1 x TS1500 , 1 x +3e, 1 x timex 2040 printer, 1 x timex 2020 cassette deck, siclair printer and some spectrum

Lardo Boffin
Posts: 811
Joined: Sat Nov 26, 2016 2:42 am

Re: ZX81 rebuild

Post by Lardo Boffin » Wed Jul 11, 2018 11:46 pm

Another day another issue... :cry:

So the zeddy works perfectly when connected to my Chroma - lovely picture.

I have fitted a ZX8 (with the extra bit to keep the picture going) but cannot get it to work! I have fitted about 15 of these now (maybe more) so I have a reasonable level of skill in tuning them. But I cannot get this one to tune.

I can tell it is outputting some kind of signal because my telly says ‘No signal’ if I turn to the extremes of the adjuster pots. The no signal message goes if I turn back to a normal settings.

I can only assume I have damaged it during fitting? The zeddy still works fine via the Chroma so the zeddy is ok.

The back. No obvious gaffes?

EAA709B5-D10B-4477-AACB-DBBD4F845EEA.jpeg
The top.

51213BA2-435A-4C36-B61E-DE075BCDEA3F.jpeg

Please ignore the heatsink. It is how the ULA arrived. :D

I could of course remove it and just use the Chroma but I really want to complete this zeddy!
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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mrtinb
Posts: 760
Joined: Fri Nov 06, 2015 5:44 pm
Location: Denmark
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Re: ZX81 rebuild

Post by mrtinb » Thu Jul 12, 2018 9:33 am

Lardo, are you planning to get in the World's Book of Records with owning most ZX81s?
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

Lardo Boffin
Posts: 811
Joined: Sat Nov 26, 2016 2:42 am

Re: ZX81 rebuild

Post by Lardo Boffin » Thu Jul 12, 2018 4:36 pm

mrtinb wrote:
Thu Jul 12, 2018 9:33 am
Lardo, are you planning to get in the World's Book of Records with owning most ZX81s?
Would it help my case if I said I don’t actually know how many I have? :oops:

Its probably less than 10. To be fair I did refurbish and sell quite a few over the last couple of years.
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

Lardo Boffin
Posts: 811
Joined: Sat Nov 26, 2016 2:42 am

Re: ZX81 rebuild

Post by Lardo Boffin » Thu Jul 12, 2018 4:41 pm

I removed the ZX8 and tried it again with my test rig ZX8 and got a picture so the zeddy is fine. Before removing it I tried it tuned to the same position as the test one but got nothing. This is why I think I broke it. :(

Will buy a few more and try and be more careful this time.
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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