ScuzzBlog: Diaries February 2024 Entry 3rd February 2024: Post 1: Sinclair ZX - Crash course in power supplies. Sinclair ZX - Crash course in power supplies. Before I plugged in my ZX Spectrum units I have laying around I thought I would take a refresher on just what power supplies are suitable. The rule of thumb is that all power supplies with the exception of the ZX80 and later Plus2 and Plus3 are backward compatible but not forward compatible. Meaning you can use any supply on an earlier computer. Few ground rules: The centre terminal on the 2.1mm barrel connector is negative. Important cus a lot of power supplies are centre positive. Also the supply is 9V DC though the computers generally run on 7.5V to 12V. The power supply for the ZX80 is suitable only for the ZX80. The earlier power supplies can fail and damage your computer and so the 700/1200/1400 original case types are used with caution. It is wise to check the voltage supplies are correct. The units are safe to handle once unplugged. Inside is a thermal fuse and that reacts to heat. OK Which power supply went with what computer: ZX80: Unique and so ignore. ZX81 700: Would generally have had the 700 mA unit and can cope with the base unit without any expansion that uses power. Use with caution. ZX Spectrum 16K 1200: The earlier machines had the 1.2A 1200 unit and would generally be safe to use on any of the rubber key computers. Use with caution. ZX Spectrum 48K 1400: The standard Spectrum used the 1.4A 1400 type unit and suits all rubber keypad machines. Again though use with caution. ZX Spectrum+ 1400: The plus/+ was simply a basic 48K Spectrum housed in a new case. Same goes for the 1400 1.4A power supply. The unit may be marginally newer but should generally still be checked. ZX Spectrum+ 128K: This has the ribbed heat sink. The black PSU has a distinctive ribbed patterned panel to one side unique to the 128K Spectrum. Whilst backward compatible should not be used on the +2 grey unit. Be mindful that the Spectrum+ and earlier power supplies are not suitable for the 128K. Be careful of getting power supplies mixed up because the black ones can look the same in certain light. Only the 128K has the ribbed pattern edge. The 128K power supply rated 1.85A unlike the Spectrum+ at 1.4A. ZX Spectrum+2 Grey 2.1A: The Holy Grail of all power supplies. The grey ZX Spectrum+2 with tape machine has the 9V 2.1mm barrel and so will fit all earlier ZX Spectrum models. Totally backward compatible. It also has the different connector to the later black Spectrum +2 and so can not be used accidentality. Rated 2.1A it is higher rating and last of the unregulated supplies. The distinct grey colour of this unit makes it truly the only PSU you will ever need for your Spectrums. A great find if you can get hold of one. ZX Spectrum+2 Black: First regulated supply brick and should only be used on the Plus2 Black. Do not use on the +3 as it will eventually burn out. ZX Spectrum+3 Black: Second regulated supply and suitable for both the +2 and +3 black machines. Both models have a different supply connector to any of the earlier models. End technical blurb: I did kind know all that in truth as in my trolley unit next to the bench is a my stock of PSU units for my machines and I only really keep the grey one out and use it on all my ZX Spectrums that can take the connector. Still worth checking out all the same. Sinclair ZX - Crash course in power supplies. ZX80 ZX81 700 ZX Spectrum 16K/48K 700,1200,1400 ZX Spectrum+ 1.4A 1400 new casing black ZX Spectrum+ 128K 1.85A black with ribbed pattern black case ZX Spectrum+2 grey case 2.1A grey power supply. ZX Spectrum+2 black case regulated brick supply ZX Spectrum+3 black case regulated brick supply

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Last updated 3rd February 2024

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