ZX Spectrum issue 2 has only blue tints

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ZX Spectrum issue 2 has only blue tints

Post by Archive » June 28th, 2019, 7:13 am

posted by relo999 on Aug 18, 2015:

Considering Spectrum world fora seem to be dead, or near death, I think this is the best place to ask this.

Recently I've bought a 16k speccy and ran into some issues with it. Faulty keyboard, broken caps, no stable frequency, faulty lower RAM chip, it being 16k, the only being able to put out tints of blue (tested with changing the border colors) and not being able to load programs (LOAD"" only goes to a blank screen). However I assume the last might be related.

I have fixed most issues, new keyboard membrane, recapped, composite mod (not really fixing it but hey), switched out the lower RAM for a modern solution and modern 32k ram upgrade installed.

Now I only have the blue tint issue and loading issue. From the research I've done it might be that the Ferranti chip(ULA5C112E-3) might be faulty and could explain both issues as that chip deals both with loading programs and the video output as far as I could gather. However seeing as those chips are nearly impossible to get I was wondering if the blue tint could be because of another issue (or that I'm just plain wrong). (BTW have tried the colour pods with no luck)
The not loading issue might be because of a bad connection somewhere where which I'd need to check, if it isn't the Ferranti chip.
 

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ZX Spectrum issue 2 has only blue tints

Post by Archive » June 28th, 2019, 7:13 am

posted by Kaicer on Aug 20, 2015:

Hi I see you know about the ZX spectrum and maybe you can help me. I have on 48k that when turn on it only display the screen in the photo. I dont know anything about this computers but it suppose to boot in white and with the sinclair words at the bottom screen.


Image



Well I think is a 16k the board have too much unused sockets.


Image
 

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ZX Spectrum issue 2 has only blue tints

Post by Archive » June 28th, 2019, 7:13 am

posted by relo999 on Aug 20, 2015:

Yea, it should load in the a sinclair copyright screen. That is most likely an issue with one, or more, of the lower RAM chips being faulty. At this age that isn't surprising, especially considering how Clive Sinclaire LOVED cost cutting (it doesn't even have a proper solder mask on both sides of the board).
Finding out which chip is faulty would be a real pain and finding replacement chips would be hard as they can run into the same issue not to mention them being expensive. I'd recommend desoldering all lower RAM chips and replacing them with the modern variant (http://zx.zigg.net/LRR/)

And yea, that is a 16K speccy.
 

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ZX Spectrum issue 2 has only blue tints

Post by Archive » June 28th, 2019, 7:13 am

posted by Kaicer on Aug 20, 2015:

I saw the new ram of that site zigg it seems better that the original for sure and is not so expensive. Another question is can I add the other upper ram that they sell and make it 48?
 

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ZX Spectrum issue 2 has only blue tints

Post by Archive » June 28th, 2019, 7:13 am

posted by relo999 on Aug 20, 2015:

Possibly, but doubtful. Considering you are missing the 3 IC's needed to get access to the 32k, unless they supply those. I used this: http://www.bytedelight.com/?product=zx-spectrum-16k-to-48k-upgrade-set
 

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ZX Spectrum issue 2 has only blue tints

Post by Archive » June 28th, 2019, 7:13 am

posted by Kaicer on Aug 20, 2015:

Ok those other empty sockets are used too. It is worth it to have it upgraded?
 

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ZX Spectrum issue 2 has only blue tints

Post by Archive » June 28th, 2019, 7:13 am

posted by relo999 on Aug 21, 2015:

yea, most software was made for the 48k variant as the 16k variant was phased out comparatively early.
 

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ZX Spectrum issue 2 has only blue tints

Post by Archive » June 28th, 2019, 7:13 am

posted by relo999 on Sep 6, 2015:

I now got at so far I got colour, except for blue. Everything now seems fine aside from blue missing in the RGB spectrum...

Load issue solved, volume to low
 

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