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Refurbishment and Upgrade of A 16k Rubber Key Sinclair ZX Spectrum

Above is a Sinclair ZX Spectrum. It is a 16k version, with the rubber keys. This Spectrum has an Issue 2 board that was manufactured in 1983 here in the UK. The board came to me in a bad way, and I have spent considerable time repairing, refurbishing and now upgrading it to the full 48k of memory. In the early days of the Spectrum, there were both 16k and 48k versions produced. You could then get them upgraded.

So for decades, this machine had remained a 16k. So I had a good play with the 16k games like Jetpac and Artic Galaxians after refurbishing it, but I could not play the 48k games until I had done the upgrade.

I took the 16k Sinclair ZX Spectrum to my workbench. The refurbishment has:

  • replaced the old case with one in good condition
  • replaced the keyboard membrane with a brand new one. The original membranes dry out over time with age and heat. It has been nearly forty years since this Spectrum was made, so the original was not working.
  • composite video modification for composite video output instead of old analogue UHF radio wave output on Channel 36
  • “tuning” in of the video output using the trimmers on the board, to give a vibrant picture with bright colours on the composite output
  • new shiny modulator case for cosmetic use mainly now after the composite video mod
  • heatsink and voltage regulator removed and replaced with modern “cool running” regulator
  • all electrolytic capacitors replaced with high-quality Vishay and in similar blue to originals. Over time, with heat and with age, these decay and can damage other components if they go bad,
  • foam to protect the new keyboard membrane,
  • replaced the ULA with the best ULA for an Issue 2 fitted,
  • mandatory modifications made to DC-DC converter circuit. This improves reliability of the notoriously unreliable circuit that produces the voltages for the different components on the board.

Above is the 16k Spectrum after it has been upgraded to 48k. This involves adding the extra RAM chips and some logic chips and adding a link to make sure that the upper RAM is used. I also had to replace one of the IC sockets. I checked the levels on the board with a meter before powering it up. Then I fully tested the machine using a Diagnostic ROM. All tests passed! So I decided to load Mikie, a 48k game, for a quick go!

SUCCESS! And I got further in the game than I had ever done before – level four I think it was! It is a great game, written by the legendary programmer Jonathan (Joffa) Smith. Sadly Joffa is no longer with us, but he produced some superb games, mainly for Ocean and Imagine – Hyper Sports and Green Beret being two of my favourites. How Joffa managed the technical feats of making the humble Spectrum do what he did, was amazing.

So I now have another fully working, refurbished, 48k rubber key Spectrum!

I am regularly selling Spectrums and when this website is fully up and running, you will be able to buy them here!

Get in touch and let me know what you are looking for – I am always happy to put a custom bundle together for you. I have many happy customers who are happy to endorse my work, as shown on this website.

1 thought on “Refurbishment and Upgrade of A 16k Rubber Key Sinclair ZX Spectrum

  1. […] has refurbished and sold many Spectrums of all types. Another example of a 16k Spectrum is shown in this article here. These machines are sold directly if you use the Contact details here or via the PopeyMon eBay […]

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