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 talks about the first Spectrum of the Amstrad era – the Grey Sinclair ZX Spectrum +2. The Grey +2 is not to be confused with the “Black” +2 which can look like it is grey, and vice versa, depending on the light and the photos.
They are quite different machines, with the Grey PCB being closer to the Toastrack PCB than the later +2 and +3 (Black) models.
For this reason and possibly some others, some people might consider the Grey +2 to be more of a Sinclair-era Spectrum than an Amstrad-era Spectrum. But there are significant other differences.
The Grey +2 includes a “proper” keyboard, a much larger case, and a tape player (“Datacorder”) built-in. It also includes two joystick ports, plus more ports on the back that include an RGB display output as well as the normal RF output. This latter similarity is like the Toastrack.
However, it is more like the Amstrad CPC 464 in its external design. Unlike the earlier Spectrum models, its case was not designed by Rick Dickinson.
Although the case is like the CPC, the power still comes from an external power supply. On the original design of the CPC, there was only one plug, for the monitor and computer. The power came from a lead that went from the monitor to the CPC. And unlike a lot of Amstrad’s products that only needed one plug (including the CPC), the Grey +2 needs more than one plug, because it needs an external display.
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.
None of the UK1400 power supplies above are suitable for any other model of Spectrum – not the 128 “Toastrack” and not the (Amstrad-era) Spectrum +2 Grey.
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.
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 +2 Grey needs more than 1.4A. It also needs more than 1.85A, so the Toastrack PSU is not suitable for the Grey +2.
The Grey +2 power supply can deliver more current. It can give 2.1A. Here is a photo:
You can see in the photo above that the case is grey and has the textured right-hand-side, which is different to the Spectrum Plus UK1400 PSU. It is very similar to the Toastrack PSU, but grey instead and with a different label.
On the underside of the PSU, you can see in the photo above that there is no model number and the maximum current is 2.1A. The label is quite different to Sinclair-era PSUs.
Compatibilities and Incompatibilities Between Spectrum Power Supplies
The Grey +2 power supply can deliver a maximum of 2.1A. Its barrel connector is similar, although it is slightly different. It has the same polarity as the Spectrum 128 Toastrack, the Spectrum Plus and the rubber key 16k and 48k Spectrum. So it can be used on these models.
However, the reverse is not true. The PSUs for the rubber key, Plus, Toastrack Spectrums cannot be used on the Grey +2. It needs too much current, so they may fail, especially when the +2 is using the tape player and/or using peripherals.
The Toastrack PSU is compatible with the rubber key Spectrums and the Plus, because it can deliver more current than they use, even with peripherals. But to say again – not on the Grey +2.
The Grey +2 PSU cannot be used on the Black +2 or +3. For a start they have a DIN connector, and internally to their power supplies, as well as inside the computer, they are very different.
In the photos above, you can see that the Grey +2 PSU is very similar to the earlier versions of the Spectrum PSU. But not the same. It is a full wave bridge rectifier.
The manufacture is superior to many of the UK1400’s that I’ve opened up. It is safer, due to the mains wires being insulated well, plus there is a clamp and the terminals are soldered to the wires at the bottom of the case. Not all UK1400 designs have a clamp, although some do. On the UK1400, the mains wire connects on the top of the transformer. The PCB soldering on the Grey +2 PSU is also superior. But these are just two examples of a superior PSU. And so it should be, it is years after the first Spectrum.
Apart from the colour of the case, and minor other design differences inside, the Grey +2 is very similar to the UK1850 (for the Toastrack). BUT THE MOST IMPORTANT FACTOR IS THE MAXIMUM CURRENT RATING – it is lower on the Toastrack PSU than on the Grey +2 PSU.
Again – please carefully check the compatibilities stated above, to avoid ruining your PSU and/or your Spectrum!
If you are looking to buy any Sinclair power supply 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. This series will conclude with the Amstrad-era models of the Spectrum, the Black +2 (Part 4) and the +3 (Part 5). When I finally get my Spectrum Next (that I’ve already paid for via the Kickstarter 2), I might even do an article on that, too! Watch this space!
P.S. According to one Speccy fan, it appears that the rare Issue 1 Spectrum used an earlier version of the power supply, not the UK1400. And according to the great JoulesPerCoulomb on Youtube, even a UK700 was used. But as I’ve said elsewhere, you cannot trust either the original manufacturer, or other people who may have fiddled around with the PSU before you got it. So you need to check in all cases, no matter what the label on the PSU claims!