ZX-81 Corrupted text display

Discussions about Sinclair ZX80 and ZX81 Hardware
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1024MAK
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Re: ZX-81 Corrupted text display

Post by 1024MAK »

^ what Moggy said :lol:

It’s not until you eyes age and make life more difficult that you appreciate how good you eyes were when you were younger :lol:

I now keep a cheap illuminated magnifying glass (okay, it has a plastic lens) on my bench, in addition to good lighting, so that I can see fine details.

Mark
ZX81 Variations
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:!: 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 being good this year.
Moggy
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Re: ZX-81 Corrupted text display

Post by Moggy »

It's not only me with the lens and the lights then!? :lol: :oops:
Jelvis
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Re: ZX-81 Corrupted text display

Post by Jelvis »

Oh ye of little faith. I knew i should have put a pic up of the other side of the board to :D

Couldn't agree more about lighting and magnification, my eyes are all about extra photons these days.

Mike
Jelvis
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Re: ZX-81 Corrupted text display

Post by Jelvis »

Just a final update. New ULA 81 fitted in a socket from Charles at vRetro who I have to thank for getting the chip from New Zealand to the UK in under a week from ordering!!

I still have a few bits to do, check mic and ear sockets for correct operation, replace regulator with something more modern, some sort of bypass for the modulator and check the 16K pack I got with it but it now appears to be working as intended without the graphics corruption.

Once more thanks again to everyone who get me here with their suggestions and checks.

Mike
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Moggy
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Re: ZX-81 Corrupted text display

Post by Moggy »

Another one back in the land of the living, well done Jelvis your persistence paid off! :D
redgatemodels
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Re: ZX-81 Corrupted text display

Post by redgatemodels »

:D
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1024MAK
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Location: Looking forward to summer in Somerset, UK...

Re: ZX-81 Corrupted text display

Post by 1024MAK »

Good news :D 8-)

If doing further work, please do take precautions against static and make sure the board has been powered down for at least a couple of minutes before starting work. This is because the vLA81 is not as hardy as the old technology ULA.

Also be careful with the expansion port/edge-connector.

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor 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 being good this year.
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