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I have some ZX Spectrums, and in some of them I observe a kind of "disintegration" process of the main board. The connectors break away etc. During the tests one of the boards burned out :(.

How can I stop or slow down this ageing process?

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This answer is not strictly related to your question: you can re-create PCB (nowadays PCB manufacturing is cheap) and then just resolder key components on the newer one (also replacing such things as electrolytic capacitors). If you already have a broken ZX, accurate soldering off of all components could be made, then the empty PCB could be both sides scanned -- like it is a piece of paper. After that, newer PCB drawing in some CAD would be next to trivial.

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The ULA chip in the ZX Spectrum (48K version at least) has been completely (100%) reversed engineered by Chris Smith. He released the design to the public (look up his book...it's amazing) and since then, people have created new boards that will fit in a ZX Spectrum case. These boards (along with off-the-shelf components) can recreate the functionality of the ZX Spectrum.

Also, the keyboard membrane, keyboard connector and case have all been remade recently. You can literally build a new ZX Spectrum in all kinds of colors and run 100% of the software (or so I've read). All without emulation! This is pretty amazing in my opinion.

Those boards are on eBay. Look for "Harlequin".

One example is here:

http://www.malinov.com/Home/sergey-s-blog/buildingzxspectrumclone-harlequin-part1

That site uses a 3D printed case but since then, there have been professional cases made using the original molds.

Now, if creating a modern version of the ZX Spectrum is not your cup of tea, then there is no reason why you can't recap the board and "future proof" it as best you can. The ULA is about the only chip you need to worry about. The others can be replaced pretty easy and there are tons of new equipment made for it.

I suggest watching these videos on repairing ZX Spectrum's.

https://www.youtube.com/user/JoulesperCoulomb

He's pretty much the expert on repairing ZX Spectrum's. Also, he sales (or at least he used to) a modern SRAM replacement for 16K/48K Speccy's.

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    The videos at youtube.com/user/JoulesperCoulomb are just great. Thank you @cbmeeks for sharing this. – Adam Boczek Aug 12 '18 at 7:39
  • @AdamBoczek my pleasure. Even though I'm more of a 6502 man, I love his videos. I wished he would make more. Also, I have purchased his ZX Spectrum RAM expansion board and it was very professionally built. Worked great. Took my 16K Speccy to 48K with modern chips. – cbmeeks Aug 13 '18 at 12:26
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    I don't understand which part of this answer addresses the question (How can I stop or slow down this ageing process?) - please can you remove the irrelevant parts and just keep the bit that explains how to reduce the rate of deterioration. – Toby Speight Aug 13 '18 at 13:59
  • @TobySpeight my answer was in the "spirit" of keeping a ZX Spetrum alive for a long time either through creating a new, modern one (using new parts that aren't 30+ years old) or by recapping original equipment where I provided expert videos for this process. Of course I cannot literally provide an answer on how to slow down or stop the ageing process of anything. No one can. If I could, I'd still be 21 years old with my 45 year old knowledge. – cbmeeks Aug 23 '18 at 13:06
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Preserving PCBs of that age is possible. Firstly, replace any components that might leak, such as capacitors. Plastic parts such as IC sockets and connectors can be replaced too. Then you can move on to the actual PCB itself.

The PCB is made up of multiple layers. The most important one is the copper layer which carries electrical signals. It is protected by a top coating that stops it oxidizing and degrading, but the coating itself can get damaged or degrade over time.

It is possible to replace both the copper and upper layers with some work. The copper layer can be fixed by cutting strips of thin copper to patch damaged tracks. The solder resist layer on top of it can also be patched up manually.

  • Do you known any good video tutorial how to "replace both the copper and upper layers"? – Adam Boczek Aug 20 '18 at 9:38
  • Here's an example, there are lots more: youtu.be/E3YEKqEqleg – user Aug 20 '18 at 10:41
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There's no way to reverse the process. Old wire PVC insulation age-hardens and the plastic used in connectors becomes brittle. The plastic basically oxidizes - plastic rust, you might say. If you wanted to stop the process you could keep the computer in a sealed tank of nitrogen.

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Actually, there isn't much on a ZX Spectrum mainboard that would require specific care or couldn't be replaced with parts still available. The ZX Spectrum is simple enough to be easily replaced and all major parts are still available, so, if we're talking decades instead of centuries, the situation is quite good (The ZX Spectrum was made in such large quantities that, beyond off-the-shelf replacement mentioned in this answer, you can easily find a donor for parts. I'm not mentioning this because this would be my last resort for repair - Every ZX Spectrum which is still around deserves to be preserved). The only things that actually "age" significantly are the capacitors on the board and anything made from plastic:

  1. The Spectrum is specifically annoying as it is known to sometimes literally self-destruct if you're unlucky and some of the electrolytic capacitors have lost capacity. See this answer for details. That is probably what happened to one of your computers. So, before even switching on a ZX Spectrum new to you, replace the capacitors. This is a MUST.
  2. One specific component which might seem hard to replace is the ZX Spectrum ULA, but since recently, there are replacements available based on modern technology (Search for NebULA or ULAPlus, the latter not available in hardware atm, to my knowledge).
  3. Keyboard connectors are increasingly hard to find, they are, apparently, no longer made. So, treat them with some respect and don't abuse them.
  4. RAM replacement modules are available that replace the 4116 and 4164 RAM chips of the Spectrum with more modern (static RAM) chips.
  5. All other electronic components are still made or can be replaced with modern equivalents.
  6. The PCB itself is really hard to break (other than by horrible layman repair attempts), but even then it is possible to replace it with, for example, a modern Harlequin board.

So, from an electronics point of view, the replacement situation is quite good, very probably better than with any other 8-bit computer. Mechanical components (especially the keyboard connectors) are a bit harder to replace, even if complete case and keyboard replacements are manufactured in China. Plastics are aging, and replacements have become rarer. An easy way to preserve a ZX Spectrum for a long time is to store it in proper conditions. Plastics are sensitive to extreme heat and UV (sunlight), the capacitors age much faster under temperature, the metal parts are allergic to humidity and might begin to corrode. Store the computer in a dry, cool and dark place and use a replica, like the Harlequin, as an everyday machine.

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