2 Oldies from under the dust. Can we fix them??

[Moggy]

But I thought that ULA mainly fails because gets too hot?

The design of the ULA is such that it is intended to run hot. This is 1980s technology. Very low power chips came along later...
And for some reason, people think that if it’s too hot to touch, something must be wrong. Yet they don’t do that with valves (tubes), conventional filament light bulbs, or internal combustion engines...

The internal operating temperature of a semiconductor chip can be up to between 100°C and 125°C

Mark

Speaking as someone who served a very short apprenticeship servicing what was known as a universal amplifier(till father decided a couple of guineas a week wasn't enough), the kind found in 50's 60's record players, I have to say that the heat and smell of a UY85 rectifier valve was something to behold especially as most cheap Dansette type record players used to put 70 odd volts from a tapping off the record deck motor winding through a valve that only required 38 volts at the heater.

I love the smell of burning Bakelite in the morning.

[Yobe]

Hi,

Yes, the Recom or Traco are the ones I had in mind.
So pictures of people adding a small heatsink to the ULA is, be polite, "stupid". OK, lets skip that one, makes it more easy...

I also saw some replacing the sockets with gold plated, but indeed lets first try IPA. If that works, why fussing around with the board.

Final question (have been bothering you guys already enough).
On the forum I see multiple solutions to get composite out of ZX81. Any suggestions what solution is good? Or all quite similar?

Again thanks a lot!

Yorick

[Paul]

Pokemon's ZX8CCB (or whatever they're called) are simply the best!
Kind regards Paul

[Lardo Boffin]

Pokemon's ZX8CCB (or whatever they're called) are simply the best!
Kind regards Paul

+1 to that. I have fitted over 30 of them.

[1024MAK]

Link to the listing for Pokemon’s ZX8-CCB (ignore that this listing is for the ZX80, this module works for both the ZX80 and the ZX81, Pokemon normally has a listing for each computer when he has some modules available).

See also this topic about the changes as a result of BREXIT.

I do recommend Pokemon’s ZX8-CCB. But if you want something simpler, have a look at the link in my signature below.

Mark

[1024MAK]

So pictures of people adding a small heatsink to the ULA is, be polite, "stupid". OK, lets skip that one, makes it more easy...

Err, if you search the forum you will see that this subject gets talked about a lot.

And obviously opinion varies. Some are in the camp that fitting a heatsink may help extend the life of a ULA chip.

Others, believe that fitting a heatsink to a plastic encapsulated chip fitted to a board in small plastic case with little ventilation does not make any significant difference. This post is my most recent comment on the subject, but do follow the link in it to where I explain much more.

And there is also this topic where we discuss heatsinks...

Mark

[Moggy]

Yes the ZX8-CCB is an excellent device which I have used quite a bit and as for gold plated sockets I personally think that's overkill for such a simple computer but if you fancy it then go for it.

Also don't worry about asking questions Yobe how else are you going to learn about the zeddie and trust me the people here are more than happy to share their knowledge and I have learned so much from the gurus on this forum.

[Paul]

Gold plated sockets are ideal for gold plated devices. If the pins of your devices are golden then go for gold plated sockets.

[1024MAK]

Good plated works best if both the plug and the socket are both gold plated.

If there are different metals, even if one is gold, if there is any dampness or moisture, then there will be a reaction between the different metals... [Although if used in a nice dry warm place, this should not be an issue].

Otherwise keep to tin plated or nickel plated connectors

Mark