Issue 4B Spectrum with dot crawl in black and white

Lardo Boffin
Posts: 936
Joined: Sat Nov 26, 2016 2:42 am

Re: Issue 4B Spectrum with dot crawl in black and white

Post by Lardo Boffin » Wed Dec 19, 2018 8:06 pm

Thanks Mark. I had seen these on eBay.

https://www.ebay.co.uk/itm/20x-Monolith ... %7Ciid%3A1

Would they be suitable? Hoping yes but they only cost a couple of quid so no worries if not. :D

I can’t see any posting dates on spectrum for everyone. I could ask Adam.
ZX80
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
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

User avatar
1024MAK
Posts: 2320
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: Issue 4B Spectrum with dot crawl in black and white

Post by 1024MAK » Wed Dec 19, 2018 9:06 pm

They look fine.

Mark

Lardo Boffin
Posts: 936
Joined: Sat Nov 26, 2016 2:42 am

Re: Issue 4B Spectrum with dot crawl in black and white

Post by Lardo Boffin » Wed Dec 19, 2018 9:18 pm

:D
ZX80
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
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

Lardo Boffin
Posts: 936
Joined: Sat Nov 26, 2016 2:42 am

Re: Issue 4B Spectrum with dot crawl in black and white

Post by Lardo Boffin » Fri Dec 21, 2018 1:29 am

Fitted the new caps and it certainly reduced the jail bars. It made little difference to the stability of the black however.
I tried another identical ULA from a work in progress Spectrum (a 4S) and it made no difference. I also put back the original Z80 (that I removed to make the DIVMMC work) and that made no difference.
There are no obvious signs of a lower RAM chip having been replaced.
I’m using a modern PSU.
The stability is a lot better on other tellies but still not as good as my other Spectrums.
I guess its possible its always been like this but with the RF quality it was never obvious.
Looks like I will be keeping this one!
ZX80
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
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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