There are several types of Sinclair ZX Spectrum. So it follows that there are several different types of power supplies for the Sinclair ZX Spectrum.
This ranges from the rubber key 16k and 48k models, then Plus and 128 models during the Sinclair ownership of the Spectrum brand, through the Amstrad ownership of the Spectrum brand (after Alan Sugar’s Amstrad bought the rights to the Sinclair Computer brand), to the present with the new Spectrum Next.
This article (Part 2) talks about the only 128k Spectrum of the Sinclair era – the Sinclair ZX Spectrum 128 (a.k.a. “Toastrack”).
The Toastrack computer looks very similar to the Spectrum Plus, but has a huge black heat sink on the right-hand-side of the case. Hence the name, the “Toastie” or “Toastrack”. Inside, it is quite different, as well as the obvious extra RAM.
The power supply (PSU) shown in the photo above is a UK1400 model, which is OK for use on 16k and 48k rubber key models. The one below is the Spectrum Plus version of the UK1400.
Like the computer itself, there is a similar look of the Plus PSU and Toastrack PSU.
None of the UK1400 power supplies are suitable for any other model of Spectrum – not the 128 “Toastrack” and not the (Amstrad-era) Spectrum +2 Grey.
This is despite the fact that the DC (computer side) barrel connector will fit on these later models of Spectrum. And despite the fact that the Spectrum Plus UK1400 looks very similar to the Toastrack PSU.
Why? Because the power requirements of the Toastrack and Grey (subject of a future article) are higher than the 16/48 and Plus. They require more current than the UK1400 can deliver.
The UK1400 model is called the UK1400 because it delivers a maximum of 1,400 mA (milli-Amps). Or put another way, 1.4A (1.4 Amps).
The Toastrack needs more than 1.4A.
The Toastrack power supply can deliver more current. It can give 1.85A. This is why it is called the UK1850. Here is a photo:
You can see in the photo above that the case has the textured right-hand-side, which is different to the Spectrum Plus UK1400 PSU.
On the underside of the PSU, you can see in the photo above that the model number is UK1850 and the maximum current is 1.85A. The quality of work inside seems to be higher than in some of the UK1400 models.
The official Toastrack power supply is becoming hard to find now, especially in a decent condition. This is the only one that I have, at the time of writing. So I have not been able to do a comparison of the internals, like I did in Part 1 with the UK1400 model.
This Toastrack PSU needs some work to clean it up and to replace the mains cable, but it has been tested including an electrical safety (PAT) test and it is working. The PAT test failed due to a nick in the mains cable insulation, so it would not be for sale in the PopeyMon eBay shop until that was fixed. But it’s the only I have, at the time of writing!
I will happily sell you one – fully tested and working – for the Spectrum 16/48k/Plus, for the grey +2 or the black +2 or +3. I also have a lot of other Spectrum parts, working computers and games for sale. I will happily put together a custom bundle for you.
I will be writing more about more Spectrum power supplies in the near future. Watch this space!Part 3 is now here.
Above is the inside of a Sinclair ZX Spectrum, the Spectrum Plus. It has a refurbished Issue 3B PCB. This Printed Circuit Board (PCB) was repaired, refurbished and enhanced by PopeyMon Games and Fun, including the DC-DC Mod that makes the power supply circuit more reliable.
It is also installed with new, quality Vishay electrolytic capacitors and a modern switched voltage regulator. The heat sink has been removed, because the original 7805 regulator and Sinclair power circuit and supply design was the source of most of the excess heat.
There are several types of Sinclair ZX Spectrum. The Spectrum Plus is simply a new case for the same PCB as the 16k and 48k rubber key Spectrum.
So it follows that there are several different types of power supplies for the Sinclair ZX Spectrum. The Sinclair UK1400 PSUs for the 16k, 48k and Spectrum Plus are interchangeable.
The Spectrum ranges from the rubber key 16k and 48k models during the Sinclair ownership of the Spectrum brand, as shown in the photo above, through the Amstrad ownership of the Spectrum brand (after Alan Sugar’s Amstrad bought the rights to the Sinclair Computer brand), to the present with the new Spectrum Next.
This article talks about the first Spectrums of the Sinclair era. This includes:
the rubber key Sinclair ZX Spectrum with 16k of RAM
the rubber key Sinclair ZX Spectrum with 48k of RAM
the hard key Sinclair ZX Spectrum + (Plus) with 48k of RAM and black case
the Sinclair ZX Spectrum 128 (a.k.a. “Toastrack”), although only briefly, in relation to the earlier PSUs. A separate article is forthcoming soon.
The power supply (PSU) shown in the photo above is a UK1400 model. They may also have found their way to be used on a Spectrum Plus, although the official Spectrum Plus PSU comes in a different case that matches Rick Dickinson‘s superb design of the Plus machine itself.
The rubber key PSUs and the Spectrum Plus PSU are interchangeable, because the Spectrum Plus is the same machine inside, with a new case, keyboard and reset button. They all have the same polarity, voltage and current delivery.
Model name: UK1400
Input: 240V AC
Output: -12.5V DC approx., unloaded (unregulated), maximum current rating 1.4A (1,400mA and hence the name UK1400)
Polarity: Centre Negative (not positive) Outer Positive (not negative as on most barrel connectors)
As noted elsewhere, the polarity of these PSUs is unusual – centre negative, outer positive.It is essential that this is correct, and many so-called “replacement” PSUs available have centre positive. Getting this wrong could seriously damage your Spectrum!
Years ago, I bought one from a bad seller on eBay who claimed it was compatible. When I challenged him after receiving it, he said it was suitable. BUT IT WASN’T. Don’t worry, I did not put my beloved Spectrum in danger. I got a refund. He changed his mind when I challenged him with the technical facts.
The UK1400 power supplies are not suitable for any other model of Spectrum – not the 128 “Toastrack” and not the (Amstrad-era) Spectrum +2 Grey. This is despite the fact that the DC (computer side) barrel connector will fit on these later models of Spectrum.
Why? Because the power requirements of the Toastrack and Grey are higher than the 16/48 and Plus. They require more current than the UK1400 can deliver.
This model is called the UK1400 because it delivers a maximum of 1,400 mA (milli-Amps). Or put another way, 1.4A (1.4 Amps).
Both of these examples are an implementation of a full wave bridge rectifier with single smoothing capacitor. You can see that even within the same design, there are variations:
Ignoring the rubbing off of the red paint on “ZX POWER SUPPLY”, the labels are different between the two PSUs. To give just two differences, although there are more, one has one style of the Class 2 symbol (the square inside a square), but the other a different style. One has the model number UK1400 underlined, but the other does not. While these may be superficial differences, they show variations even before you get inside the PSU. It is believed that different contractors came up with different designs to deliver the specification given by Sinclair in their contracts – something evidenced by the fact that there was a recall (see the Safety article).
Inside the PSU, there are variations even within the same design. The design in these two examples has the PCB mounted at right angles to the transformer, whereas other designs has the transformer mounted top-down on top of the PCB. The internals of the case are different between designs, so the designs are not necessarily interchangeable internally, because the mounts and orientations are different.
The side-mounted PCB on the left-hand-side (LHS) is different to the PCB on the right-hand-side (RHS). One has the components on side one side, and the other has them installed differently. The capacitor is mounted differently too.
The transformer blocks are of different manufacture. One has foam on top (believed to avoid hum when operating), the other does not.
The RHS PSU shows the notorious problem of the strain relief breaking. The previous owner has just “tied a knot” on the inside of the case. This is not good. It can be repaired using a clever design with heat-shrink tubing, or a replacement DC cable could be installed by someone who takes care. I have done this.
Both of these PSUs are faulty and have failed the PopeyMon functional and/or PAT (electrical safety) tests, so are not for sale. Only when they have been fully repaired and tested would they be put for sale. I have sold many of these.
So you can see that:
There are a variety of designs of the Sinclair ZX Spectrum over the years.
There are a variety of power supplies for those designs of Spectrum.
And even within those types of power supply, there are variations.
Collectors love variations. They show the history of the Spectrum, its quirks and foibles, and people absolutely love the Spectrum. I am only showing just one implementation for one design of PSU for the 16/48 Spectrums, which I already have said, is also suitable for the Plus. There are other designs, which I have not shown here.
Before use, in any of these cases, they need to be checked for safety, as well as functionality and that they are delivering the right voltage levels, current and polarity. So please note that they must be checked before use, and check the Safety article.
If you are looking to buy one or want one checked, please get in touch. I will happily sell you one – fully tested and working – for the Spectrum 16/48k/Plus, for the grey +2 or the black +2 or +3. I also have a lot of other Spectrum parts, working computers and games for sale. I will happily put together a custom bundle for you.
I will be writing more about the Spectrum power supplies in the near future. Watch this space!Part 2 is now here.
I would like to credit and highly recommend the excellent videos by “JoulesPerCoulomb” on Youtube. “Greetings and good time of day…” to whoever this mysterious but extremely helpful man, is. His video on power supplies was a brilliant starter a few years ago to the many hours of research that I have conducted on Spectrum power supplies, and which I present in this series of articles.
UPDATED (30/12/20) to add the PCB Layout Diagram for the +2B, taken from the Spectrum +2B/+3B Amendment Service Manual. I am checking this against actual PCBs, so please bear with me. As stated in the article below, there are (at least) two versions of the PCB used in the +2 black Amstrad-era Spectrums.
I like all models of the Sinclair ZX Spectrum. They all have their pros and cons.
The original rubber key 16/48k Sinclair ZX Spectrum and its Sinclair-era Spectrum successors – the Spectrum Plus and the Spectrum 128 – all relied on an external tape player to load games from cassette, using tape leads between tape player and Spectrum.
When Clive Sinclair sold the Sinclair computer brand to Alan Sugar, Sugar transferred some of the design ideas that were also used on the Amstrad CPC range of personal computers.
The Amstrad CPC was released after the Spectrum, so Amstrad could learn from the shortcomings of the earlier Sinclair machine. But the CPC had a lot of catching up to do, especially when it came to games.
The CPC still used a tape player to load games but it was built into the same case as the keyboard. This followed Sugar’s repeated philosophy, as he had earlier used on his audio equipment, of everything in one box – although the CPC monitor was physically separate, there was only one plug for everything.
So the Sinclair ZX Spectrum +2, the first Amstrad-era Spectrum, built on the success of the Spectrum and as I’ve already said, used some of the design ideas from the CPC:
an all-in-one case, very similar to the CPC case, with RF display output (old analogue) and higher-quality RGB display output. The monitor had a separate plug and power supply, and was not included with the computer. This was different to the original Amstrad CPC, which only had one plug.
a built-in tape player, called a “Datacorder” and with this name emblazoned across the tape player window. No more tape leads to fiddle around with.
a proper keyboard – no more of the rubber keys and what some people call its “dead flesh” feel. A proper hard keyboard that is very similar to what we use on our Windows PCs, Linux machines and Apple computers today.
128k of RAM, which when released seemed like a lot of memory when you were used to just 48k
a new three-channel sound chip that was added to the TV sound – no more beeper
The first Amstrad Spectrum was the grey +2, which used a lot of the design of the Spectrum 128 “Toastrack”.
Next came the black (I think of it more of a dark grey) +2A, +2B which were tape players and the disk version +3 which had another Amstrad “innovation”/”annoyance” – 3″ disks – not 3.5″, not 5.25″ but 3″. Yes, really!
The black +2 models also had a separate power supply. The notoriously unreliable DC-DC converter circuit was removed from the design between the grey +2 and black +2 models. A separate power “brick” (it is about as heavy as a brick!) dealt with supplying the different voltages on separate pins of a DIN plug. This improved reliability of the Spectrum, and looked after the power for the Datacorder.
Here, I am looking at the tape players/Datacorders. Elsewhere on the World Wide Web, it is stated that there is only one version of the tape player in the +2A and +2B.
But this is not the case.
If you look very carefully, you will see some differences. They may well be minor, but there are nevertheless some differences.
If you are the first to contact me with all of the differences between the two models of tape drive, you will receive a free prize (UK only sorry!) as well as the satisfaction that you have a keen attention to detail! Sadly, NOBODY WON THE COMPETITION, AS NOBODY GOT THE ANSWERS RIGHT!
I should mention that I service and sell these Datacorders, for the black +2 and grey +2 models, as well as fully-working computers including refurbished and modernised ones.
I also sell external tape players for the Sinclair-era Spectrums.
So get in touch and I will put together a bundle of stuff for now at a good price with superb service.
The above Product Recall warning is from Personal Computer News in March 1983. It is a recall of power supplies for the Sinclair ZX Spectrum – the rubber key 16k and 48k models, as shown in the photo below.
They may also have found their way to be used on a Spectrum Plus (hard key, black model), although the Spectrum Plus power supply comes in a different case that matches Rick Dickinson’s superb design of the Plus machine itself.
These will work on the 16k/48k rubber key and the hard key Plus machines, if they are still serviceable. These power supplies are not suitable for any other model of Spectrum. But they need to be checked for safety, as well as functionality and that they are delivering the right voltage levels and polarity.
There was a potentially very serious fault with the design.
Sadly, quality control could be an afterthought at Sinclair. But cheap prices and time constraints often meant quality suffered. This was the case with the rest of the Spectrum design, especially the notoriously unreliable power circuit on the Spectrum board itself. But let’s face it – this trade-off between price/quality/time is how so many people’s lives were transformed by the Sinclair ZX Spectrum.
So why the Recall? Some units were produced where the mains 240V could potentially become live on the outer metal positively charged part of the barrel connector – despite this supposedly being the low voltage DC connector. Details of the units with the fault are shown on the recall notice. This is why I have made the image large, so that you can read it – if you can’t read it, please get in touch.
The Spectrum power supply was unusual in that the DC barrel connector that brought power to the computer was designed to be centre negative, but outer positive. Most power supplies of the time have centre positively-charged and outer negatively-charged. Like many things, Sinclair did this differently.
So if a user slipped on the smooth barrel connector plastic when plugging it in, and the fault with the mains 240V has occurred, they could have been injured or killed if they slipped off the barrel connector onto the metal! Or it could kill or injure your Spectrum too.
I am showing this here as a service to Spectrum users because some of these power supplies could still be out there in the wild and still emerging from storage or other places. Some of them have a sticker on the bottom if they have been checked after the recall. Only unethical sellers would remove these stickers – they should be kept on to show they have been checked.
And I am also showing you this as a safety warning, especially as some online sellers seem unaware of these faults and others I have seen have actually hid faults with power supplies that are being sold on eBay. This puts Spectrum users at unnecessary risk.
Other power supplies could have suffered damage during and since the 1980s. So it is wise to have them checked over properly, before you use one on your valued Spectrum.
I have sold many of these power supplies for the Spectrum. But unlike some online sellers, I am certified trained as an electrical safety (PAT – Portable Appliance Test) tester. All power supplies are fully PAT tested and will not be sold by PopeyMon Games and Fun if they fail the test.
I log all test results, as required by law. And I don’t sell them with illegal plugs on them – again, unlike some other sellers. Some sellers have power supplies with live and neutral pins that are unshielded on the plugs. This is illegal. I have even received some with cracked plugs! This is the mains 240V, not low voltage, so is very serious.
I replace illegal, outdated or unsafe plugs with new ones and with the right rating of fuse. This is part of the quality service that I provide. You cannot trust other sellers who don’t do this – ask them!
And if you are looking to buy one or want one checked, please get in touch. I will happily sell you one – fully tested and working – for the Spectrum 16/48k/Plus, for the grey +2 or the black +2 or +3. I also have a lot of other Spectrum parts, working computers and games for sale. I will happily put together a custom bundle for you.
I will be writing more about the Spectrum power supplies in the near future. Watch this space!
Above is the inside of a Sinclair ZX Spectrum +2 that I bought online. This is one of the models that Amstrad produced when Alan Sugar bought the Sinclair computer brand from Clive Sinclair. It is a later issue 4, also known as the +2B.
The ad for the computer did not have photos of the inside! I would describe it as an insect zoo. The other machine from the same supplier was not as bad, but it was still pretty bad.
It is the worst example of a machine that was not looked after by its previous owners. Many others that I get hold of, are in much better condition, and some are in near mint condition. The condition of a Spectrum is a major factor on the price, as well as whether it is fully working or not.
It is testament to the quality of manufacture by Amstrad that this filthy machine, when cleaned up, worked! It did take a lot of work though!
I now use this machine as a test machine, and have fully cleaned it up and fully tested it, with repaired tape drive and fully repaired and cleaned keyboard.
How dirty is your Spectrum?
What is the worst condition that you have seen one in?
I always try and test the computers that I buy, fix them and in some cases, fully refurbish them. That depends on what my customers want.
I sell them with accurate descriptions, as much as is possible.
If there are still any outstanding issues, I list them, so that my customers know in advance of buying. Many online sellers are not so honest.
If there are then any problems, all I ask is that they contact me to rectify them problems first.
Get in touch at the Contact details here. I will happily sell you parts or whole machines, or anything else Spectrum that you are looking for – games, joysticks, replacement cases, replacement keys, and so on. Just ask and I will check my stock.
Above is a Sinclair SJS1, a joystick that was specifically designed for the Sinclair ZX Spectrum +2 when Amstrad’s Alan Sugar took over the Sinclair computer brand from Clive Sinclair.
Unlike most other joysticks of the era, it does not use the same “pinouts” as the Atari standard. It does use the same “D-sub” 9-pin connector. But they do not match the standard developed by Atari for the 2600/VCS console and copied by many others.
The SJS1 only has one fire button on the stick, which you have to use your thumbs for. This is OK for using with games that don’t use fire much. But terrible for shoot-em-ups!
I have tried to stick up for this joystick amongst fellow Spectrum fans, and also tried to do a wind-up of them, to show the SJS1 playing the arcade version of Ms. Pac-Man.
I tried to get people to guess how it was possible. Then in the big reveal, I showed them this:
The SJS1 joystick is connected to the board from a 4-in-1 Namco Plug and Play joystick game board thingy, which was broken. The joystick was removed from the board and the case, and the board was then repaired by me. I then had to find a suitable home for it.
It is housed in a case from a Quickshot joystick for the MSX – again, another broken joystick that was recycled. The board from that joystick was beyond repair.
I attached the joystick wires so that it was according to the Atari standard. So I had to create a wire to re-wire the Atari standard to Alan Sugar’s “Amstrad-Sinclair” proprietary standard.
And hey presto! The arcade Ms. Pac-Man, emulated on a board, in an MSX joystick case, controlled by an Amstrad-era Sinclair joystick! All powered by a battery!
It’s OK playing Ms. Pac-Man. But it’s terrible for playing Galaga, an old favourite of mine, which is on the same board! The SJS1 joystick is hated, and rightly so. But it remains the only joystick that is custom-designed for the Sinclair ZX Spectrum Grey +2.
GREAT EXPERIMENT and IT WORKS! I just have to be very careful when I move it 🙂