48P-KDLX – Replacement Plus Keyboard Review

The 48P-KDLX in kit form.

PokeMon is perhaps better known for his range of products for the ZX80 and ZX81, chiefly the ZX8-CCB which has played a huge part in providing decent video output from these machines. He’s also the mastermind behind the ZX80Core and ZX80More clones, and the ZXBlast device that allows you to control more than one nuclear power station at a time from your ZX81 🙂

Occasionally he turns his hand to the Spectrum though, and this time he’s produced a product which replaces the membrane on a 48K Plus or Toastrack with a PCB containing surface mounted tactile switches.


The 48P-KDLX installed.

You can buy the 48P-KDLX as a PCB only, as a full kit or as a completely assembled device. The difference in price is so small as to leave self-assembly as an unnecessary inconvenience, unless you’re suitably inclined (like yours truly). Components are surface mount, but sufficiently widely spaced to make assembly quite easy with liberal amounts of flux.

The 48P-KDLX installs in place of the membrane and backplate, with just the bubble mat being required to be left in place. Nylon washers are supplied to allow for the difference in thickness when replacing the keyboard screws. Finally the 5 and 8-way keyboard ribbons can be inserted into the keyboard molexes and the machine reassembled.

First impressions – well, wow. The bubble mat keyboards as used on the 48K Plus, 128 Toastrack and QL are much maligned for their lack of feel, but with a 48P-KDLX installed there is positive tactile feedback with an audible click with each keypress. The keyboard is transformed and is suddenly a pleasure to type on.

I’m reliably informed that adding 12mm discs between each key in the bubble mat and the PCB improve the experience even further, although I haven’t tried that myself to date.

The only drawback I would note (and it’s an extremely small thing) is that the keyboard ribbons are quite stiff and the mechanical fit in the keyboard sockets is a little haphazard – I would have liked to have seen some 0.6mm thick PCB fingers provided for this. It’s a tiny issue though.

The 48P-KDLX is available from www.sellmyretro.com.

Overall marks: 9/10.

Code monkey from Dublin. I may have one or two old computers...