Hello All & Dead ZX .. probably

Discussions about Sinclair ZX80 and ZX81 Hardware
thedevworks
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Joined: Mon Mar 04, 2019 5:33 pm

Re: Hello All & Dead ZX .. probably

Post by thedevworks »

fair point that was worth trying, I tried on another TV and it was a little different.

Either.. A few times I got a very steady black screen (No cursor etc, just black)

the other times I got crazy noises and patterns like in the video
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1024MAK
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Re: Hello All & Dead ZX .. probably

Post by 1024MAK »

Modern TVs, if they can’t detect the back porch part of the video signal, they get their auto calibration of the black video level wrong. This results in a very dark image even with the brightness and contrast turned up to full or nearly full.

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp

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thedevworks
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Joined: Mon Mar 04, 2019 5:33 pm

Re: Hello All & Dead ZX .. probably

Post by thedevworks »

Oh well, I tried first the CCB because it was the least disruptive, which didnt work, followed by a new ULA, which also results in the same video signal. I guess now the only thing left to do is replace the other chips!
thedevworks
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Joined: Mon Mar 04, 2019 5:33 pm

Re: Hello All & Dead ZX .. probably

Post by thedevworks »

Ok I was wrong, the new ULA does work!! Keyboard is a bit iffy, but for now, I'm happy! :D
thedevworks
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Re: Hello All & Dead ZX .. probably

Post by thedevworks »

Image

:P :P :P :D :D :D
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1024MAK
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Re: Hello All & Dead ZX .. probably

Post by 1024MAK »

Good to hear that you are up and running (well, once you have sorted the keyboard) :D

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp

:!: Standby alert :!:
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
Looking forward to summer later in the year.
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Andy Rea
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Re: Hello All & Dead ZX .. probably

Post by Andy Rea »

McKlaud wrote: Tue Mar 05, 2019 1:16 pm Dishwasher would be better ;)
i had a commodore pet universal main board ( from a cbm 4032 machine) in the kitchen sink... my missus thought i'd gone nuts... works a treat and is clean to boot now :D :D
what's that Smell.... smells like fresh flux and solder fumes...
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