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+2a PSU advice

AD-RS1600iAD-RS1600i
in Hardware
Hi all,

With my +2 being a bit of a diva I am thinking about getting my +2a recapped so I can use it for the odd game the +2 does not like, there is only one thing, after 25 years the PSU has gone missing!!

So I guess my question is, is there a new aftermarket PSU i can buy that will work with it given it odd psu plug a +2a has?

Or less preferably, if I buy an original PSU, do they still work reliably and correctly after 30+ odd years?

Any advice would be gratefully received, thanks

Adrian

Comments

  • Your Spec-chumYour Spec-chum
    Yes they are reliable I have both +2A and +3 and they are both working fine. You can use a +3 psu on a +2A too, but not advisable the other way round due to the +3's disk drive needing a little more current than the +2A psu can provide. The different din plug on these psu's is because the +2A/+3 need to be supplied with multiple voltages, hence the multi pin plug. These psu's are a much better design with voltage regulators and IC's to supply the voltages. They have fuses also for short circuit protection too. The earlier psu's are a much simpler and a bit of a crude design, just a mains transformer feeding a filter capacitor, and a simply diode bridge rectifier to convert ac to dc.
    Thanked by 1spider
  • Ast_A_MooreAst_A_Moore
    Unless you’re willing to make your own by soldering a DIN 6 plug onto a generic +5V/+12V/–12V PSU, you can import one made specifically for the +2A/+3 from Germany.

    The original PSUs are relatively reliable, but are quite a bit more complex than your regular transformer-diode–bridge-capacitor variety of the previous models. Since you don’t have a PSU, I’d go with getting a new switch-mode one, rather than trying to source an original
    Every man should plant a tree, build a house, and write a ZX Spectrum game.

    Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
    and zasm Z80 Assembler syntax highlighter.
    Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.

    A few Spectrum game fixes.
  • spiderspider
    edited June 2019
    I think its the difference in the 12V output, something like 0.2A for the +2A/B PSU and 0.6A for the +3 , given the power needed for the 3" drive, as that iirc requires a 12V supply. Not 100% on those figures sorry, its from my head. I could not see it in the manual at a quick glance and I'm a bit tired as I write this! Pretty sure the 5V output is the same amperage. I dare say someone will be able to provide the exact specs if required.

    I use a +2A one with my +3 (yes I know) but I have a 3.5" drive in it, and its not got a 12v feed to it, so *shrugs* , I'd agree though and probably not want to use a +2A one with a standard +3, going the other way and using a +3 PSU on a +2A/+2B is going to be fine as its 'got a bit more poke' so to speak.

    :)
    Post edited by spider on
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  • colonel32colonel32
    I use one of the Cisco supplies. They’re cheap and work great. Details here:

    https://spectrumforeveryone.com/technical/replacement-psu-2a-3-machines/
    Robin Verhagen-Guest
    SevenFFF / Threetwosevensixseven / colonel32
    NXtel • NXTP • ESP Update • ESP Reset • CSpect Plugins
  • colonel32colonel32
    There is also one sold here, although it doesn’t contain the -12V line.

    https://www.bytedelight.com/?product=brand-new-modern-switching-5v12v-worldwide-plug-replacement-psu-for-zx-spectrum-2a-2b-3
    Robin Verhagen-Guest
    SevenFFF / Threetwosevensixseven / colonel32
    NXtel • NXTP • ESP Update • ESP Reset • CSpect Plugins
  • spiderspider
    Is that actually needed ? I can't remember, unless its a +3 specific output/requirement. Otherwise one of those (similar to above) +5 & +12 regulated plug in or bricks would do. I have one just to use as an external HDD PSU for instance.
    Please visit the JetSet Willy & Manic Miner Community
  • Ast_A_MooreAst_A_Moore
    spider wrote: »
    Is that actually needed ? I can't remember, unless its a +3 specific output/requirement.

    It’s not +3-specific—both the +2A and +3 “use” it. I put “use” in quotes, because the only component that requires the negative 12-volt rail is the MC1488 line driver, which is used for interfacing the Speccy with whatever you plug into the AUX and RS232/MIDI ports. It’s also present on the expansion slot, so, technically, some peripherals might have taken advantage of it, though I wouldn’t know what those are.
    Every man should plant a tree, build a house, and write a ZX Spectrum game.

    Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
    and zasm Z80 Assembler syntax highlighter.
    Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.

    A few Spectrum game fixes.
    Thanked by 1spider
  • AD-RS1600iAD-RS1600i
    edited June 2019
    Thank you for all the advice, I really appreciate it - a big thank you to everyone

    The depth of knowledge on this forum is simply awesome! :)
    Post edited by AD-RS1600i on
  • AD-RS1600iAD-RS1600i
    edited June 2019
    Ast_A_Moore wrote: »
    Unless you’re willing to make your own by soldering a DIN 6 plug onto a generic +5V/+12V/–12V PSU, you can import one made specifically for the +2A/+3 from Germany.

    The original PSUs are relatively reliable, but are quite a bit more complex than your regular transformer-diode–bridge-capacitor variety of the previous models. Since you don’t have a PSU, I’d go with getting a new switch-mode one, rather than trying to source an original

    A new one ready to be used would be my preference I think - really appreciate the URL thank you.

    Post edited by AD-RS1600i on
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