ZX Spectrum +2 – Blackie – PSU Hack

… or how to power retro hardware with a modern PSU

So I wanted to connect this hard drive:

… but DAMN, there’s no nuclear power plant nearby.

… So, I’ve decided to take my work back underground … to stop it from falling into the wrong hands …

Background story

A friend of mine, V-12/Tropyx, asked me to hack a PSU for his ZX Spectrum +2 – Black. That’s the one with the Amstrad mainboard.

After a short research, I already knew that in addition to +5 V and +12 V, black +2 requires a -12 V line for normal operation. I was like hmmm … hmmmmmmm … and all of sudden I came up with an idea to use a cased PSU from a small PC that I disassembled a while back.

At least it sounds brilliant but was a bit harder to achieve … kk is not that hard after all 😉

PC PSUs have a lot of various voltage lines and -12 V is there as well, along with +12V/+5V.

The power socket in this speccy is a simple DIN-6 and I already had these plugs ordered for a different project (external SD2IEC). Soooo to work!

Sorting out an expansion port

First, I had to disassemble this unit to sort out an expansion port. Without it cleaned I wouldn’t be able to test my setup since the only hardware to load stuff on a speccy that I have is Divide2k14 by Lotharek.
Standard procedure was involved (I don’t have all photos though) which is cleaning, applying solder, and removing solder surplus with a soldering wick then reapplying a thinner layer of solder.

Curiosity time: I was surprised when I saw an SMD chip mounted in a wicked but cool way.


PSU after unscrewing the top cover looks like this.

I’ve removed all unnecessary cabling and secured the remaining cables inside.

I also needed a power on/off switch just for convenience.
PC PSUs are turned on by a motherboard. There is a special signal cable (usually green lead) for this task.
The solution is super simple. Green lead has to be grounded to keep PSU turned on and that can be done through a switch, which is what I did right after cutting out a hole in a case for it.

After assembly.

I’ve also put a large shrink tube around the PSU case to make it look neater and shrank it with a hot-air (black would look better but I had only a blue one :()

I’ve hooked it up to a Speccy and connected Divide2k14 turned on power aaaaaand the moment of truth …..


I was greeted with a boot screen (through a crappy RF output though)

And that’s it.
Machine works and V-12/Tropyx can now run his hardware without a problem 😉
I wish him more great demoscene productions … on a C64 of course 😉


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