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Hi to All

Posted: Tue Dec 19, 2017 10:39 pm
by McKlaud
Hi All,

I bought ZX81 on auction a few weeks ago and it flashed back my first contact with this microcomputer when I was 6-7 years old. I bought it as faulty unit, but with few touches it showed the "K" cursor on the screen. I managed to upgrade the internal memory from 1KB to 16KB, played a few demos and games that required 16KB memory pack and it has worked flawlessly since then.

My only concern is that the ULA is getting very warm quickly. I hope it would not fail soon.

My Zeddy below:
Image

Cheers
Claudius

Re: Hi to All

Posted: Tue Dec 19, 2017 10:58 pm
by sirmorris
Hi Claudius! Welcome aboard :D

Don't worry about the ULA failing - they do get very warm. It's normal. There has been some ... lively debate on whether something should be done. There are 2 sides.

No - just enjoy it, these things are made for playing and no-one can say whether a hot ULA is a problem.
Yes - put a heatsink on it and install a fan!!

There is no definitive winner as yet ;) Me - I say play away!!

Re: Hi to All

Posted: Wed Dec 20, 2017 8:12 am
by Lardo Boffin
One thing I think everyone agreed on was to replace the power regulator with a modern one - that significantly reduces the amount of heat being generated inside the case.

Re: Hi to All

Posted: Wed Dec 20, 2017 8:45 am
by McKlaud
@Lardo Boffin: I did this at the time when I upgraded RAM to 16K. Anyway thanks for the advice.

Re: Hi to All

Posted: Wed Dec 20, 2017 9:21 am
by sirmorris
Oh and running from a regulated 7.5v supply works wonders, too!

Re: Hi to All

Posted: Wed Dec 20, 2017 12:18 pm
by Moggy
Having bit the bullet and fitted a 40m fan inside the case with a suitable vent on the top front edge near to to the ULA I can honestly say that after using a smoke match to view airflow the mod has some merit.

Now as for heatsinks MWWAAAAAA!!! :twisted: :twisted: :twisted:

Almost forgot welcome to the club Claudius and a nice file-sixty keyboard you have there and everything Sir Morris and Lardo said too. :D